Eliminating the Floating Barrel/Shroud on Mrod

[Gertrude]

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.



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

[Motorhead]

Love it !! ...... Agree on "Un floating" ...... Been also doing nearly the same with positive results 

[ShootingBlind]

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.



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

[Ribbonstone]

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.

[gene_sc]

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

[Motorhead]

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  pending color of foam used being it comes in MANY 



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. 

[Gertrude]

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. 

[Gertrude]

Scott,
That looks like it will work just as well as the O-ring.

[trinket]

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  pending color of foam used being it comes in MANY 



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 !

[haywire2]

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?

[Nomadic Pirate]

I will never again buy a gun with a floating barrel !!!
good job and thinking for that fix.

[sperho]

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...

[Ribbonstone]

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.

[joel w]

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

[CitySniper]

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....

[Geoff]

Thank you for the idea.

[Gertrude]

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)

[gene_sc]

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?

[Rico14]

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.

[joel w]

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.