GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Gertrude on June 02, 2013, 02:05:32 AM
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Recently I've noticed a number of posts where members complain of POI's shifting on their Marauders.
Naturally, this can be caused by a number of different issues or a combination of them.
Often they will be told to check the usual possible causes.
These usually include making sure the shroud is tightly snugged to the breech, check the scope mounts, having the barrel properly "leaded in" with 75-100 shots, (or cleaned because of being too dirty), barrel lapping, re- crown, baffle clipping, pellet selection, action tight in the stock, and tune adjustments, to name most of them.
I've also noticed a few members mention how their Mrod seems to be shooting like a laser beam one day,... but on a later day,...
the POI seems to have shifted from a previous shooting session.
I have also experienced this strange phenomenon on more than one occasion with my .22 Mrod, as well as on my daughters and my best buddies. That makes 3 different Marauders that I have personally witnessed the same condition.
What I suspect, is that during a particular shooting session, we fine tune our scope adjustments, we get it hitting dead on the crosshairs, and we are satisfied. we have our fun, finish our shooting session, and put our rifles away for another day.
It may sit for a few days laying in a rifle case, standing in the safe, or sitting on a table on it's bipod.
Then, a few days later, we shoot some more,.. yet the POI has shifted,... and nothing has been changed or touched on the gun, since the last time we sat down and shot them.
I think there is a possibility that the barrel/shroud moves ever so slightly, thus changing the POI.
I've never really been a huge fan of the floating barrel/shrouds, and I've seen posts where others here feel the same way.
Some have said they wrap teflon tape around the shroud to take up some gap in the barrel band, and I've even seen where a popular aftermarket parts maker of air strippers, is now starting to produce machined bushings to fit the I.D. of the barrel band, to reduce or eliminate the gap, to the O.D. of the shroud.
Good idea I think,... but a bit pricey.
Here's an easier, quicker, and much cheaper way to stabilize the shroud inside of the barrel band.
I picked this up at the local Ace / True Value Hardware Store.
(http://i111.photobucket.com/albums/n148/tri5ron/Benjamin%20Marauder/IMG_6921_zps925ce0ca.jpg)
It fits very snug around the shroud (VERY minor stretching necessary), and inside the barrel band.
You will need to loosen the set screws to allow for a "self centering" of the barrel band to the shroud, as well as prevent from pre-loading the floating barrel in any undesired direction.
Use a toothpick or similar tipped tool to shove it into the gap of the barrel band, as it is a very snug (perfect) fit, and pay attention to evenly apply pressure upon installing. Verify the barrel band is pushed all the way onto the fill valve, and tighten the set screws.
I actually installed 2 of these. one at the front, and one at the rear sides of the barrel band.
Result: ZERO barrel/shroud movement within the barrel band.
No more floating barrel !
Cheap, easy, and easily removable !
Total cost: under $2
(http://i111.photobucket.com/albums/n148/tri5ron/Benjamin%20Marauder/IMG_6915_zpsbd6c6ef6.jpg)
(http://i111.photobucket.com/albums/n148/tri5ron/Benjamin%20Marauder/IMG_6914_zpse9e3e99c.jpg)
(http://i111.photobucket.com/albums/n148/tri5ron/Benjamin%20Marauder/IMG_6917_zpsb282ae2d.jpg)
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Love it !! ...... Agree on "Un floating" ...... Been also doing nearly the same with positive results ;)
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Nice pics, nice solution. Isn't it neat when Occams Razor comes around again and cuts out a M-rod problem? The simplest explanation and solution are usually the best. And in this case, likely the quickest and cheapest too. Thanks for the info.
Recently I've noticed a number of posts where members complain of POI's shifting on their Marauders.
Naturally, this can be caused by a number of different issues or a combination of them.
Often they will be told to check the usual possible causes.
These usually include making sure the shroud is tightly snugged to the breech, check the scope mounts, having the barrel properly "leaded in" with 75-100 shots, (or cleaned because of being too dirty), barrel lapping, re- crown, baffle clipping, pellet selection, action tight in the stock, and tune adjustments, to name most of them.
I've also noticed a few members mention how their Mrod seems to be shooting like a laser beam one day,... but on a later day,...
the POI seems to have shifted from a previous shooting session.
I have also experienced this strange phenomenon on more than one occasion with my .22 Mrod, as well as on my daughters and my best buddies. That makes 3 different Marauders that I have personally witnessed the same condition.
What I suspect, is that during a particular shooting session, we fine tune our scope adjustments, we get it hitting dead on the crosshairs, and we are satisfied. we have our fun, finish our shooting session, and put our rifles away for another day.
It may sit for a few days laying in a rifle case, standing in the safe, or sitting on a table on it's bipod.
Then, a few days later, we shoot some more,.. yet the POI has shifted,... and nothing has been changed or touched on the gun, since the last time we sat down and shot them.
I think there is a possibility that the barrel/shroud moves ever so slightly, thus changing the POI.
I've never really been a huge fan of the floating barrel/shrouds, and I've seen posts where others here feel the same way.
Some have said they wrap teflon tape around the shroud to take up some gap in the barrel band, and I've even seen where a popular aftermarket parts maker of air strippers, is now starting to produce machined bushings to fit the I.D. of the barrel band, to reduce or eliminate the gap, to the O.D. of the shroud.
Good idea I think,... but a bit pricey.
Here's an easier, quicker, and much cheaper way to stabilize the shroud inside of the barrel band.
I picked this up at the local Ace / True Value Hardware Store.
(http://i111.photobucket.com/albums/n148/tri5ron/Benjamin%20Marauder/IMG_6921_zps925ce0ca.jpg)
It fits very snug around the shroud (VERY minor stretching necessary), and inside the barrel band.
You will need to loosen the set screws to allow for a "self centering" of the barrel band to the shroud, as well as prevent from pre-loading the floating barrel in any undesired direction.
Use a toothpick or similar tipped tool to shove it into the gap of the barrel band, as it is a very snug (perfect) fit, and pay attention to evenly apply pressure upon installing. Verify the barrel band is pushed all the way onto the fill valve, and tighten the set screws.
I actually installed 2 of these. one at the front, and one at the rear sides of the barrel band.
Result: ZERO barrel/shroud movement within the barrel band.
No more floating barrel !
Cheap, easy, and easily removable !
Total cost: under $2
(http://i111.photobucket.com/albums/n148/tri5ron/Benjamin%20Marauder/IMG_6915_zpsbd6c6ef6.jpg)
(http://i111.photobucket.com/albums/n148/tri5ron/Benjamin%20Marauder/IMG_6914_zpse9e3e99c.jpg)
(http://i111.photobucket.com/albums/n148/tri5ron/Benjamin%20Marauder/IMG_6917_zpsb282ae2d.jpg)
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Good write up.
Results are what counts, and if that cures the problem of wandering zero, then it's a great solution. Pretty much a "perfect" solution: ost very little to try, doesn't modifiy any parts, and if you don't like the results can un-do it.
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Lets get to the cause of the issue. The biggest problem I see is miss handling of most PCP's. Especially the M-Rod's. Barrel floats, right? well what I see with the M-Rod shifting from day to day is many folks lean the M-Rods barrel against something like a wall or even a rifle rack putting pressure on the barrel from the wt. of the rifle. These M-Rods and other with free floating barrels are not meant to be placed in a storage position with weight against the barrels.
You can get by with this type of storage with most springers but certainly not a PCP, IMO
Gene
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My cure on "NEWER" rifles utilizing the larger clearance barrel supports, is slide off the support and REMOVE the I.D. o-ring. Then using 1/16" hobby foam ( One side adhesive ) line the I.D. of support with a strip cut to width and length. End result looks like this :o pending color of foam used being it comes in MANY ;D
(http://i1320.photobucket.com/albums/u532/scott_schneider1/DSCI0025_zps309d84d1.jpg)
Older rifles with the smaller supports, replacing o-ring with a 1/16" x 1"o.d o-ring closes the gap to zero making a nice firm fit eliminating wiggle. ;)
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Gene,
I completely agree. Floating barrels should never be subjected to any type of pressure.
But here's what I find odd.
My best buddy keeps his camper at my house. His gun is kept in a rifle case in the camper... laying on it's side,... lid not closed or latched.
My rifle sits in my camper, on it's bipod, on the table. No side pressures at all on the barrel/shroud.
My daughters sits next to mine on her bipod.
All 3 guns have experienced this happening.
Now the POI usually doesn't change by very much on mine or my daughters rifles, but they do a little bit. maybe 1/2"- 3/4" at 50 yds.
on the other hand, my buddies rifle, on average, has had more of a shifting POI issue.
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Scott,
That looks like it will work just as well as the O-ring.
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My cure on "NEWER" rifles utilizing the larger clearance barrel supports, is slide off the support and REMOVE the I.D. o-ring. Then using 1/16" hobby foam ( One side adhesive ) line the I.D. of support with a strip cut to width and length. End result looks like this :o pending color of foam used being it comes in MANY ;D
(http://i1320.photobucket.com/albums/u532/scott_schneider1/DSCI0025_zps309d84d1.jpg)
Older rifles with the smaller supports, replacing o-ring with a 1/16" x 1"o.d o-ring closes the gap to zero making a nice firm fit eliminating wiggle. ;)
Excuse me but.... Huh?? Adhesive,colored Hobby foam ?? ??? - What and where please !
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If I'm not mistaken, the reason for the floating barrel is to separate the barrel from the air tube. As the tube is pressurized, it will expand slightly and may move in one direction or the other. As you shoot, you release this pressure and the tube contracts slightly, and once again, may move in one direction or the other. My question is this. If the barrel and shroud are now "attached" to the moving tube, would this not also cause a shift in POI as you shoot? In other words, are you jumping from the frying pan to the fire?
For those of you who have tried the above fix, have you now noticed an improvement in how the gun maintains a steady POI, or are you seeing shifts regardless?
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I will never again buy a gun with a floating barrel !!!
good job and thinking for that fix.
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I think they used to come with o-rings in the barrel band...
I'm interested in seeing some 10 shot groups with and without if you could...
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Better test, but it would take a week.
Four 5 shot groups on three different days (no scope adjusting) with out the o-ring. Then again for another 3 days with the o-ring.
I did just that test when getting a Discovery to stay put day ofter day, putting it in a gun-sock and letting it take a ride to and from work on the floor boards of my Jeep. Didn't expect BETTER accuracy, just that the gun shot AS WELL and stayed on target.
LEts put it this way. A 1/2" shooting gun that has shown a random group center shift of 1/2" inch (and most that do shift around are much worse) is the same as hunting with a gun that can only shoot into 1". If it shifted those tiny 1/2" groups by 1" every so often, then think of it as a 1 1/2" gun.
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I had the same issue for the first week or so with the POI shifting around. It seemed to be a common issue here and other forums. So, I cut the yellow barrel cap that came with the gun down to a 1/4" ring and have been using that as a spacer for several weeks with great success. The dimensions are the same as the above o-ring's OD and ID.
Joel
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I have never had my POI change from day to day or week to week on my Marauder. Gene said it already but a lot of people do not handle their guns good.
I never grab my Barrel/shroud when handling, I do not lean my barrel or shroud on anything! I have seen plenty of youtube videos of people leaning their Barrel/shrouds on trees, picking their guns up by the shroud, poking dead animals with their gun. etc.
Basically a lot of people are not taking care handling the gun....(I totally trust the free float, I have accidentally bumped the barrel a couple times and it still held zero..... When putting my gun away in the closet it stands up against the wall balancing on the scope turret,butt pad and bi-pod ...3 points of contact none of them the barrel.
Sperho...all the barrel bands have an O-ring....
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Thank you for the idea.
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If I'm not mistaken, the reason for the floating barrel is to separate the barrel from the air tube. As the tube is pressurized, it will expand slightly and may move in one direction or the other. As you shoot, you release this pressure and the tube contracts slightly, and once again, may move in one direction or the other. My question is this. If the barrel and shroud are now "attached" to the moving tube, would this not also cause a shift in POI as you shoot? In other words, are you jumping from the frying pan to the fire?
For those of you who have tried the above fix, have you now noticed an improvement in how the gun maintains a steady POI, or are you seeing shifts regardless?
Michael,
You may be correct, in that the reason for the floating design, would be to allow for any air tube expansion.
(Yes pressurized air tubes DO expand on some degree).
Of course, the amount of expansion depends on many things.
These can include, total volume, total length, materials, methods of construction, temperature, and ambient pressure.
Example- A DC-10 / MD-11 aircraft "Grows" as much as 4" in length, between sitting on the ground, and flying at altitude.
(ever wonder why aircraft develop cracks in their structures over time ?... it's not ONLY because of vibrations).
Naturally, the air tubes on our airguns would see VERY little expansion comparatively,... yet it would be, or could be enough to be measurable, and therefore of enough concern in design, to allow for it.
I think that the O-rings would allow for any minuite growth of the air tube, and still hold it steady to protect from any side pressures of forces that might cause the POI to be effected.
I'm hoping to do a multi-day test soon. I may even do a controlled test, with one rifle being "un-modified", (the control), and the other rifle to be the variable test subject.
I think it would also be interesting to see if other members here could do the same testing and compare results.
(all from a bench rest position, of course)
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Yes that is exactly right. If you use a barrel strap and it is connected directly to the barrel and air tube, Filling the tube with air will move the barrel. This is something to consider.
Gene
If I'm not mistaken, the reason for the floating barrel is to separate the barrel from the air tube. As the tube is pressurized, it will expand slightly and may move in one direction or the other. As you shoot, you release this pressure and the tube contracts slightly, and once again, may move in one direction or the other. My question is this. If the barrel and shroud are now "attached" to the moving tube, would this not also cause a shift in POI as you shoot? In other words, are you jumping from the frying pan to the fire?
For those of you who have tried the above fix, have you now noticed an improvement in how the gun maintains a steady POI, or are you seeing shifts regardless?
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Has anyone ever posted about having a POI shift in a Prod? The Prod has a floating barrel also. I've never had this happen to my Prod.
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I have never had my POI change from day to day or week to week on my Marauder. Gene said it already but a lot of people do not handle their guns good.
It's nice to hear from owners that have not had these issues. That gives me hope! It makes me think twice about how I grab the gun now and store it as I am probably guilty of mishandling it.
I think the grouping is better with free floating than it is with the above mod but if the POI changes when the barrel is floating then that accuracy advantage really is a wash IMO.
I am going to do some more testing when I get more supplies in (ammo, cleaning pellets, bore cleaner and polish) and go back to free floating and start with a super clean barrel and JSB's and proper handling.
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I did just that the other week when I accidently ordered the wrong rings size 7/8id and it fitted nicely inside the barrel band. Btw, it would help too if you put an extra oring to keep the baffles tight from shifting.
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So it's not strapped down with the o-ring, still free to slide in and out from linear expansion. Radial expansion would be minimal as the barrel band is pretty much over the tube end/fill end cap.
If free floating works for you, use it. If a connected band works, use that. I can't really make a blanket statement that one is "better" than the other, just that on an individual basis one will suit that gun better than the other.
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Good idea.
Went to Home Depot.
The rings are about $1.75 for 10 in the plumbing dept.
I took off the clamp, rolled on a ring to almost where it would end up, then put the clamp back on and pushed the ring to its final location.
Rolled in a second ring and pushed them into the clamp with toothpick as suggested.
Then, I wrapped a piece of playing card around the barrel and smoothed out the insertion.
I did this on my .22 and the .177 both of which are zeroed at 20 yards.
The .22 shot about 2 inches high and 1 inch right after installation.
The .177 shot about 3 inches right after installation.
I re-zeroed the scopes.
I think I can see a difference.
Can't hurt anything to try it out.
I know Scott used tape inside the clamp and a little silicone to slide it on the barrel.
Same result.
Good luck.
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Hi Tri-Ron and other airgunners.
As you know, I've been struggling with this issue but discussing it on the Marauder Air Forum.
The point is, it still is semi-free floating, but it is now constrained in two dimmensions (up/down, side/side). It can still move independent of the air tube front/back (with the length).
Neil Clague started this idea over on the Crosman/Benjamin Yellow forum by making solid parts out of aluminum. He believes the o-rings allow too much movement too, but I like your idea and I will try it out later this week.
I tried making just the outer spacers this weekend out of aluminum tube that was nearly the right size. They make a clear improvement on both my 25 M-rod and my 22 M-rod. I also made one for my P-rod, but did not notice much change yet - perhaps because the barrel is so short maybe it is not an issue with the P-rod. I'm still not sure why, but maybe it is only an issue for some Marauders. I did try the spacer with both shroud 1/4 turn loose and fully tight. I got more consistent groups with the shroud tight.
I mostly shoot at a minimum of 30 to a max of 50 yards and I use high magnification scopes 21X or 24X. What I have noticed with my M-rods is whenever I clean the barrel, the POI changes. As I'm shooting my guns, the POI may change a tiny bit then it will move back to where it was set. Whenever I transport my guns in a good gun case, the POI always changes a very small amount. I use good scope mounts (BKL) and good scopes (I've bought quite a few to try out) and have eliminated the scope and rings as a possible source of the issue.
I am very careful never to handle the barrel/shroud (except when cleaning) and never to lean the barrel as some have mentioned in other posts, so that is not the issue. When I do accuracy testing, I use a solid rest and tether my airgun to a large tank in the sweet spot of its fill range.
I'm still in the testing phase. I will try your o-rings first, but I also ordered one of Neil Clague's solid aluminum set. He said he can't get to them for a while because he is swamped making LDCs.
Ray
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Tried this and results were not so good. So until I have a real deviation will keep her a free floater. But thanks for the write up.
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If I'm not mistaken, the reason for the floating barrel is to separate the barrel from the air tube. As the tube is pressurized, it will expand slightly and may move in one direction or the other. As you shoot, you release this pressure and the tube contracts slightly, and once again, may move in one direction or the other. My question is this. If the barrel and shroud are now "attached" to the moving tube, would this not also cause a shift in POI as you shoot? In other words, are you jumping from the frying pan to the fire?
For those of you who have tried the above fix, have you now noticed an improvement in how the gun maintains a steady POI, or are you seeing shifts regardless?
Michael,
You may be correct, in that the reason for the floating design, would be to allow for any air tube expansion.
(Yes pressurized air tubes DO expand on some degree).
Of course, the amount of expansion depends on many things.
These can include, total volume, total length, materials, methods of construction, temperature, and ambient pressure.
Example- A DC-10 / MD-11 aircraft "Grows" as much as 4" in length, between sitting on the ground, and flying at altitude.
(ever wonder why aircraft develop cracks in their structures over time ?... it's not ONLY because of vibrations).
Naturally, the air tubes on our airguns would see VERY little expansion comparatively,... yet it would be, or could be enough to be measurable, and therefore of enough concern in design, to allow for it.
I think that the O-rings would allow for any minuite growth of the air tube, and still hold it steady to protect from any side pressures of forces that might cause the POI to be effected.
I'm hoping to do a multi-day test soon. I may even do a controlled test, with one rifle being "un-modified", (the control), and the other rifle to be the variable test subject.
I think it would also be interesting to see if other members here could do the same testing and compare results.
(all from a bench rest position, of course)
May I suggest you do the sentivity on one rifle since one rifle will not preform exactly the same as the other. Really looking forward to checking out the results.
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What is the greater evil? Constraining the barrel on the end drastically changes the dynamic response of the barrel. The Crosman engineers indended for the barrel to be free floating so, the structural modes would be like a tail wagging, constrained on one end only. However, if you throw a metal shim sandwiched between the barrel guard, its constraining an additional point on the OTHER side, so the barrel FLEXES differently during the shot. In this case, the fundamental mode is drastically different and the barrel could flex in an inaccurate manner.
I am not a gun designer, but it seems that a free floating barrel is better based on firearm experience. HOWEVER, if the shroud design is such that it causes the barrel to reside in a different position over time due to bumping, gravity, etc.. than it could be better to constrain for POI; however, it would make sense the group diameter could increase. And POI could slightly change with reduced pressure...
Another idea.. An oring is NOT the same as a aluminum bushing. An oring is like a spring, if soft enough, it will have less influence as a boundary condition (includes damping) and barrel can still act like "free floating" versus the aluminum bushing... If the oring helps position the barrel for "repeatibility" and still generates an approximate "free floating" boundary condition, this might be the best solution..
Hobby foam, oring of various durometers, and metal bushings could very well produce drastically different results..
Just depends on the dynamics... lots of testing necessary to determine which is better..
I can tell folks are getting pretty excited about the possibility of reducing groups.. I hope it helps...
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My cure on "NEWER" rifles utilizing the larger clearance barrel supports, is slide off the support and REMOVE the I.D. o-ring. Then using 1/16" hobby foam ( One side adhesive ) line the I.D. of support with a strip cut to width and length. End result looks like this :o pending color of foam used being it comes in MANY ;D
(http://i1320.photobucket.com/albums/u532/scott_schneider1/DSCI0025_zps309d84d1.jpg)
Older rifles with the smaller supports, replacing o-ring with a 1/16" x 1"o.d o-ring closes the gap to zero making a nice firm fit eliminating wiggle. ;)
Excuse me but.... Huh?? Adhesive,colored Hobby foam ?? ??? - What and where please !
1/16" thick 8x10 sheet of Hobby / Craft foam cut to fit I.D. of support ;)
(http://ts1.mm.bing.net/th?id=H.4529666816936040&pid=15.1)
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Hi Tri-Ron and other airgunners.
As you know, I've been struggling with this issue but discussing it on the Marauder Air Forum.
The point is, it still is semi-free floating, but it is now constrained in two dimmensions (up/down, side/side). It can still move independent of the air tube front/back (with the length).
Neil Clague started this idea over on the Crosman/Benjamin Yellow forum by making solid parts out of aluminum. He believes the o-rings allow too much movement too, but I like your idea and I will try it out later this week.
I tried making just the outer spacers this weekend out of aluminum tube that was nearly the right size. They make a clear improvement on both my 25 M-rod and my 22 M-rod. I also made one for my P-rod, but did not notice much change yet - perhaps because the barrel is so short maybe it is not an issue with the P-rod. I'm still not sure why, but maybe it is only an issue for some Marauders. I did try the spacer with both shroud 1/4 turn loose and fully tight. I got more consistent groups with the shroud tight.
I mostly shoot at a minimum of 30 to a max of 50 yards and I use high magnification scopes 21X or 24X. What I have noticed with my M-rods is whenever I clean the barrel, the POI changes. As I'm shooting my guns, the POI may change a tiny bit then it will move back to where it was set. Whenever I transport my guns in a good gun case, the POI always changes a very small amount. I use good scope mounts (BKL) and good scopes (I've bought quite a few to try out) and have eliminated the scope and rings as a possible source of the issue.
I am very careful never to handle the barrel/shroud (except when cleaning) and never to lean the barrel as some have mentioned in other posts, so that is not the issue. When I do accuracy testing, I use a solid rest and tether my airgun to a large tank in the sweet spot of its fill range.
I'm still in the testing phase. I will try your o-rings first, but I also ordered one of Neil Clague's solid aluminum set. He said he can't get to them for a while because he is swamped making LDCs.
Ray
If a person wanted to test the sensitivity; why not use some "wood" shims to jam between the shroud barrel and barrel guard at three points? This material is much stiffer than rubber... and could be very quick.. of course its not permanent..
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I think where I went wrong was when the POI shifted after the mod install, I adjusted the scope to the new POI instead of adjusting the o-rings or barrel band to bring the barrel back to zero where it was when it was free floating.
Shooting with a slightly curved or unrelaxed barrel..
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I think where I went wrong was when the POI shifted after the mod install, I adjusted the scope to the new POI instead of adjusting the o-rings or barrel band to bring the barrel back to zero where it was when it was free floating.
Shooting with a slightly curved or unrelaxed barrel..
Indeed, have a material in the gap, barrels is going to be stiff too rotate within support and settle back into it's natural position.
So ... some purposeful alignment to get barrel re-centered over air tube before tightening support set screws is required.
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Indeed, have a material in the gap, barrels is going to be stiff too rotate within support and settle back into it's natural position.
So ... some purposeful alignment to get barrel re-centered over air tube before tightening support set screws is required.
So I finally got some .25 pellets in and got to do some testing this morning. I started with the shroud and air stripper off. I zero'ed the scope and then put the air stripper on and re-shot and noticed a POI shift to the right about 1/2" at 51 yards. My air stripper is modified with three large elongated holes tapering to the back. I had randomly installed it with 2 holes on the left side and one hole on the right. So I rotated the air stripper so I had one hole on the top and two holes on the bottom to the left and right. Shooting again my POI was now just a bit high, but re-centered. (if your air stripper is stock, ignore this part)
Now, I installed the shroud, baffles, o-ring and end cap. This dropped the POI back to where it was with a naked barrel. From here I installed the o-rings into the barrel band but no matter what I did, my groups were all over the place ranging from 2" -1.5" groups at 51 yards with 25.4g JSB kings.
With the o-rings removed and now back to a free floating barrel my groups dropped to just over .780" or nickel size.
Here is 8 shots at 51 yards in some mild wind. (more like .845 than .810, I goofed)
(http://i44.tinypic.com/330y9gg.jpg)
5 more shots at 51 yards 20 mins later. A small POI shift but i think temp has something to do with it.
(http://i44.tinypic.com/zo97c.jpg)
At 10yds (i said 20yds earlier, my bad) with 5 shots, there is one single clean pellet sized hole.
(http://i40.tinypic.com/30cyg7p.jpg)
For my Mrod at least, I will stick with a free floating barrel for now. Maybe try another scope to rule this one out.
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Yepper ;)
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well I am finally going to be able to do some shooting this coming weekend.
Will be heading out to a buddies place in Temecula on friday night or early saturday morning, coming home sunday evening.
I am looking forward to testing out the O-ring idea on both mine and Camerons .22 Mrods.
we will be shooting at various distances, and possibly out past 100 yds.
Hoping for good weather and no wind.
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well I am finally going to be able to do some shooting this coming weekend.
Will be heading out to a buddies place in Temecula on friday night or early saturday morning, coming home sunday evening.
I am looking forward to testing out the O-ring idea on both mine and Camerons .22 Mrods.
we will be shooting at various distances, and possibly out past 100 yds.
Hoping for good weather and no wind.
Temecula...No wind? Good Luck. I took the rings out and all is good.
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I have never had my POI change from day to day or week to week on my Marauder. Gene said it already but a lot of people do not handle their guns good.
I never grab my Barrel/shroud when handling, I do not lean my barrel or shroud on anything! I have seen plenty of youtube videos of people leaning their Barrel/shrouds on trees, picking their guns up by the shroud, poking dead animals with their gun. etc.
Basically a lot of people are not taking care handling the gun....(I totally trust the free float, I have accidentally bumped the barrel a couple times and it still held zero..... When putting my gun away in the closet it stands up against the wall balancing on the scope turret,butt pad and bi-pod ...3 points of contact none of them the barrel.
Sperho...all the barrel bands have an O-ring....
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From here I installed the o-rings into the barrel band but no matter what I did, my groups were all over the place ranging from 2" -1.5" groups at 51 yards with 25.4g JSB kings.
With the o-rings removed and now back to a free floating barrel my groups dropped to just over .780" or nickel size.
For my Mrod at least, I will stick with a free floating barrel for now. Maybe try another scope to rule this one out.
Thanks. Finally some good target shooting to test the theorizing. It makes no sense technically to couple the muzzle end of the barrel/ shroud to the air tube which is subject to differing amounts of expansion from varying air pressure and also from shifting from pressure from different holds on the foregrip. This is the big problem with the Airforce SS rifles accuracy since the barrel is mounted to the shroud at both ends and the foregrip is mounted to the shroud following a fairly flexible frame. The best groups from any air rifle with a long barrel would probably be with the shroud removed. But it is worth it to have something really quiet.
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If the barrel of a Marauder is really that wiggly in the receiver then the fix has to down at that area. Keep in mind when discussing .22 Marauders that they are notorious for pellet fussy, loose bores, outright bent barrels, and mediocre group sizes.
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Barrel is not hog-tied to the inside of the shroud, so the expansion/contraction aspects should be covered by that "slip fit".
Certainly wouldn't bother trying the shroud o-ring trick on a gun that shoots great and has a stable POI, but evidently not all of them are so blessed. It's an easy mod that is easily reversed, so worth trying on problem guns.
Would also pay attention to the fixation of the shroud at the rear.
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Man o man did I stir the wrong pot of beans :-\
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Man o man did I stir the wrong pot of beans :-\
Yep.
That was last year Tim.
As I wrote in your other post, I have since put the rings back in and I them. I was witness to Scott cleaning the course at the Diablo Range in Concord, CA with his rifle set up with the hobby tape. In fact, I was the scorekeeper and target re-setter. Very impressive performance....
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One thing I've learned over the past 20yrs slinging wrenches is you listen every time a old timer opens his mouth, period!
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Not really the barrel to breech (although that’s worth a check), it’s the shroud to breech that can give problems.
If I remember M-Rods well enough, there is a separate part that butts up to the receiver and is set screwed in place. The shroud screws onto that separate piece. Threads are a spiral inclined plane and develop a lot of torque when you tighten the shroud. The set screw’s detents in the barrel are not a close fit, so you can pull that separate shroud attachment part away from the receiver hen tightening the shroud. (yeah, I know, a bass-ackwards case of making something loose by tightening it too much).
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Ok, so this is an older discussion we had in the past, but since I've recently helped out a couple of new airgunners that have purchased Mrod's, and getting their guns set up.
So I thought I'd bring this back for their benefit, and hopefully any others who may still struggle with shifting POI's.
No,...This is not a "magic fix" for all who have tried it, (and some have even said it just flat out did nothing to improve their grouping or consistency),...
....but I will say, it has worked GREAT for me, as well as some others, who are pretty darn respectable shooters in my book, (Scott, I'm talking about you here ;) ;) ;D ;D ), as well as about 6 or 7 other Mrods that I have tinkered with over the years.
Personally, I have Not Yet seen even ONE Mrod that this did not improve shot grouping.
(YMMV)
One thing I'd like to add to the O-ring method, is that occasionally dabbing a spot of 100% Silicone oil, (actually any type of lube would work in this application), rubbed onto the o-rings, and on the exterior surface of the shroud, and on the interior surface of the band,.... (before stuffing them into the barrel band) seems to also help.
My theory here, is that this will help to still allow for a "semi-floating" barrel within the shroud, allowing for minimal lineal movement when re-filling with air,... yet still maintain a "radial retention" which should prevent any up/down/left/right movement within the barrel band.
I did have one experience where after many months of the DRY o-rings being in place, that my POI had once again moved.
I had fired many hundreds of shots since the O-rings had been installed so naturally their is the consideration that it might be time to clean the barrel.
But BEFORE I went to clean the barrel, I wanted to test this theory,... So I thought that the O-rings might be playing a roll in the now shifted POI. this could possibly be from them being dry and stuck, or maybe "Taking a set", or some grit from hunting, or whatever.
I pulled the o-rings from the barrel band, cleaned them of any dust picked up from being in the field, lightly lubed them, and stuck them back in.
Result -
POI came right back to where it had been, and stayed there consistently for many more hundreds of shots... before needing to clean the barrel.
I would also suggest, that if you choose to try this little "mod" on your Mrod,... that you FIRST Loosen the 2 set screws in the bottom of the band, BEFORE stuffing the O-rings in.
This will allow for a more even "tension" of the stuffed o-ring between the shroud and the barrel band.
Then AFTER you have the lubed orings in place, (and the barrel band pushed all the way onto the filler ftg), then make sure you have the barrel centered over the airtube with NO SIDE LOADS (left or right),... Then tighten down the set screws as the LAST thing to do.
Remember, your objective here, is to NOT induce any side to side Preloads from band to shroud.
Now I understand that not everyone has had the same results, and **your mileage may vary**, but I am still sold on this idea, and will continue to use it, and suggest it to any Mrod owners out there who might be having similar issues with a shifting POI between shooting sessions.
Heck,... it doesn't cost hardly anything to try it, and it can easily be removed if your particular gun see's no benefit from it.
hopefully this may help some newer Mrod guys who have recently started in AG's, and may not have heard of this simple little "mod".
Cheers !
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Thought I'd give this a shot.
My local Ace Hardware has different stock from the original post.
(http://i1180.photobucket.com/albums/x408/mukilteo1/IMG.jpg)
It'll give me something to do tonight.
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I tried all this stuff on my .177 synrod.It hated it!I installed a 3 set screw barrel band like WAR sells.Theres a real fine line on my rifle,I tighten up the set screws to just touch then back them off a lil...just barely backing them off doesnt work either.I kinda got it down a "feel thing" just a bit of play on the shroud and it shoots good...to loose no good,to tight no good.
Our marauders are tricky critters,they take alot of tinkering,taking notes on all mods/changes is pretty darn important IMHO.
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What effect would sleaving with carbon fiber have on this problem? Or what others have done with barrel tension ?
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What effect would sleaving with carbon fiber have on this problem? Or what others have done with barrel tension ?
I sleeved my .177 Synrod barrel with carbon fiber. I believe it improved consistency. If I had to do it again, I would likely recess the CF tubing into the receiver. Doing so would require boring out the receiver as well as the rear shroud mount, but I think it would make the barrel/receiver assembly more rigid.
FWIW, my shroud is free floating within the barrel band. When I received the gun, it came with an o-ring filling the shroud/band gap. I bought it as a refurb, so I have no idea if it came from the factory that way or not. For me, for this gun, it seems to shoot better floating.
Steve
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FWIW: One option to sleaving a 177/22 barrel is using a 25 cal breech. You do have to put a spacer on the back side of the mag slot so the thinner 177/22 mags will work. I did this on a 177, but learned I should have tested the barrel before gluing on a CF sleeve. ;) The next 177 barrel I got was good, but kept it in a 177 breech, and works well with the foam tape solution.
I have tried foam tape, O-rings and the set-screw BB. The foam tape has been the most reliable solution for me on both 177 and 22 Mrods.
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FWIW: One option to sleaving a 177/22 barrel is using a 25 cal breech. You do have to put a spacer on the back side of the mag slot so the thinner 177/22 mags will work. I did this on a 177, but learned I should have tested the barrel before gluing on a CF sleeve. ;) The next 177 barrel I got was good, but kept it in a 177 breech, and works well with the foam tape solution.
I have tried foam tape, O-rings and the set-screw BB. The foam tape has been the most reliable solution for me on both 177 and 22 Mrods.
Nice to know about the .25 receiver... probably easier than possibly buggering up the .177 receiver machining it. Mine is definitely better after sleeving, but I think it might have been better with some CF into the receiver.
I'll have to try the foam tape trick or the lubed o-ring. I had an o-ring, but it was dry. I can see where that might not have as good a result as the lubed o-ring or foam tape.
My WAR SSG came in, so hopefully I'll get some tinkering and shooting time in over the weekend.
Steve