GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: SeanMP on November 08, 2013, 03:15:51 PM
-
Some time ago I got a request from Mike at Tj's to help him design a high quality barrel blank in 22cal pellet to give him a stock item to serve his growing AG clientele.
Between Mike, Bob and myself we came up with a barrel that is specifically designed to be a much higher quality replacement to factory barrels.
The barrels are forged CrMoly units with a 6 land configuration. They are initially available in 7/16 and 1/2" sizes. They are of course unmachined blanks as is usual from Tj's
I don't have Mikes approval to release the actual bore ID's/rates but after recieving my samples I can say these are absolutely what I'm hoping to see when I start out to make a finished barrel.
Shown is a push through from a raw blank
-
No clue who Tj's is ???
But a link and some price info would be great !
-
Mike Sayers at TJ's Liners
Mr Sayer
TJ's Enterprises
3652 Neltner Rd
Alexandria, KY 41001
859-635-5560
Most custom builders and gunsmith's will have Mike on speed dial :D
-
No clue who Tj's is ???
But a link and some price info would be great !
Scott-
This where Jim Gaska is getting his new M/P-rod replacement barrels from also, but designed to his specifications.
Sean-
Will these be choked, or straight bore?
-
I want one. lol.
I would love to get a 26" long for machined for my disco with .167 barrel port.
Where do I order. ;D
-
I want one. lol.
I would love to get a 26" long for machined for my disco with .167 barrel port.
Where do I order. ;D
I suspect, call Sean. Let me suggest a .167 x .250 long port; full bore area...:) If you're going to be only pellets, maybe .160x.200 oblong with goal being keep the pellet supported for the largest arc possible.
cheers,
Douglas
-
These are specifically Mike's stock inventory so you would just call him and order one and have it shipped to a barrelfitter/gunsmith of your choice.
Of which I'm just one of X number that Mike deals with on a regular basis.
Just as an aside to anyone trying to order these or anything else from TJ's. He is on vacation until the end of november
-
Sean,
Could you PM me his information. I will have to wait till he gets back from vacation. Also, I would not mind getting you to do the fitting. I have a BNM breech. Would that be a problem.
Daniel
-
Glad to see the barrel worked out, Sean.... it was fun working with you and Mike on this project.... I look forward to trying one on my 2260 HPA Gopher whacker....
RatRacer.... As per all of Mike's barrels/liners they are not choked, they are unmachined blanks, no chamber, leade, porting, or crown.... but Sean can look after that for you, including choking....
Bob
-
I would love to get it choked when the time comes
-
I would love to get it choked when the time comes
Actually IMO these blanks will not require a choke, nor will they benifit from any additional choking. They are ideally suited to a classic long taper lap.
If you look at the pic, right at the head rim, you can see evidence of full contact in the groove ID. So the long lap maintains the gas seal for the entire length of the bore. Maintaining full contact with the bore for the whole ride is superior to the quick squeeze.
However thats not to say choking is bad in and of itself.
-
very nice, glad to see more barrels hitting the market.
-
Suspect I'll try one sometime shortly, have a project in mind.
Don't think a good barrel really needs a choke. Have found them to be more pellet-picky than choked barrles, but once you find the right combination they seem to shoot well.
Might be alone in this, but back when HW barrel blanks were available (Mac 1) bought one of his close-out 5mm blanks. If there is a choke in it, I can't find it by feel, but it does shoot well.
-
SeanMP,
Maybe my mind is playing tricks on me, but did I not read that these barrels were hammer forged, and incorporated a very, very gradual taper from breech to muzzle?
Regards,
Scott
-
SeanMP,
Maybe my mind is playing tricks on me, but did I not read that these barrels were hammer forged, and incorporated a very, very gradual taper from breech to muzzle?
Regards,
Scott
Scott
Yes and no
Yes they are hammer forged but no the long taper would need to be lapped in.
-
very nice, glad to see more barrels hitting the market.
Yes I totally agree. The only real commercial player for AG blanks is totally hit and miss.
-
Glad to see the barrel worked out, Sean.... it was fun working with you and Mike on this project.... I look forward to trying one on my 2260 HPA Gopher whacker....
RatRacer.... As per all of Mike's barrels/liners they are not choked, they are unmachined blanks, no chamber, leade, porting, or crown.... but Sean can look after that for you, including choking....
Bob
Thank you for the "particulars" Bob. You knew that this was/ is going to be asked at some point.
-
I'll order 24" of barrel when it's available.
-
I'm glad to say thank I ordered one yesterday. I will be putting on my disco and increasing the barrel length from 24 to 26in. Ordered the ½ barrel. I should make its way to Sean's for machining along with my breech for fitting and a few other mods.
-
;D ;D As a new to modding ag shooter what is a decent ballpark cost for one of those barrels set up and fitted ready to shoot ?
-
I'm glad to say thank I ordered one yesterday. I will be putting on my disco and increasing the barrel length from 24 to 26in. Ordered the ½ barrel. I should make its way to Sean's for machining along with my breech for fitting and a few other mods.
Make sure to keep us informed on this new barrel, I am real curious.
Joe
-
Will do.
I do hope this works out. My current crosman barrel can deliver 0.170 to 0.25 5 shots groups (C to C) from 40 yards. The thing I don't like about the crosman barrel is that is soft and and thing. Very touchy.
-
I figure I would bring this post back to life.
I ordered the barrel form my disco and it was shipped directly to Sean. I'm still waiting for it to arrive, but I should be here in the next week or so. I ordered the ½ in think barrel and the length is 26in and Sean did his magic. I'm very appreciative towards Sean for the time and attention to detail that he put on my barrel and breech. Needless to say I'm counting the days for it to arrive so I can install and test out.
Here are some pictures and a video of the parts that Sean made and modified.
http://flic.kr/s/aHsjQC11uE (http://flic.kr/s/aHsjQC11uE)
http://www.youtube.com/embed/qrSdBhFaqRk (http://www.youtube.com/embed/qrSdBhFaqRk)
-
Looks great, but lets see some targets when it arrives!
I would also like to see if these barrels are less pellet fussy (as I suspect they may be).
Thanks for the update!
-
Update:
The barrel came in. Sean did an amazing job machining it. I can not thank him enough. I'm still waiting for a PEEK poppet to come in and then assemble.
I would be able to test it out this weekend. The one thing I did was to push a pellet through it. It is amazing how even the contact is through the whole length of the barrel. Very impressed.
-
Are you allowed to say what the total cost (blank and machining) was/is?
-
The barrel blank was about $140. For machining you would need to talk to Sean. I had a bunch of custom machining done
-
here is an update:
I got the barrel from Sean. I have to say he does amazing work. Can't thank him enough. My first test with the barrel were not that great. The groups where moving around and I just could not figure out why. I was very disappointed. I contact the Sean and he mention harmonics and he said that I should try some barrel weights.
I thought that was possibility because the length of the barrel (26) and, per Sean's information, the hardness and metal composition of the barrel. I also noticed that when shooting I was getting a lot of the barrel flipping upwards.
I have all that some thought. I did some webs searching about barrel harmonics and looked at picture of AGs with barrel weights. I found guns with weights but not with weights and shrouds. I had not idea how the shroud would affect all this.
I contacted Lloyd and asked him if he could build me a few weights out of steel with o-rings in the ID and a set screw. I can't thank Lloyd enough either. He jumped on it right away. this is what I got, 2 different size weights to test out.
(http://farm8.staticflickr.com/7324/12645916525_c65447b337_n.jpg)
Now lets fast forward to yesterday. I finally get the change to install and test the weight. I can can say is what a difference. I was shooting from 20 yards. and place 2 weights at about 4 inches from should ant then about 18. I took a few shots and the groups when down from about 1" to .25". I remove the shroud and move the muzzle weight about 1 inch towards the breech. Groups tighten up to same hole. Needless to say, I'm smiling. Today I will be moving back to 40 yards and adjusting the the weights some more.
Some pictures of the weights:
(http://farm3.staticflickr.com/2891/12645898325_f47c94bfce_n.jpg)
Drilled weight for air flow:
(http://farm8.staticflickr.com/7419/12646037343_cacaed6387_n.jpg)
Here you can see the two weights on the back. the front one is the alumimun shroud piece
(http://farm3.staticflickr.com/2810/12683795175_128f40107c.jpg)
And with the shroud on:
(http://farm8.staticflickr.com/7430/12683941803_b4ac4b8c08.jpg)
Many thanks to Lloyd and Sean for all the hard work and help
-
That's awesome news! I'm glad to hear you got it working like you wanted it to.
-
Hey Daniel
Excellent news and good work getting that setup tuned. It's not easy to do.
I hope your not scarring up my bluing job with those set screws :P
I think this is a good opportunity to get some hard facts out there on barrel dynamics because there is a definite trend going on here with the orders coming through this shop. Lately the trend of the orders I'm seeing are long thin barrels, inside shrouds because they look cool and their all stealthy in the noise department, making huge power and with extreme accuracy and I want it to be adjustable velocity
Sadly all of these things are diametrically opposed to each other. A person need to make some hard choices about what is most important for their individual needs.
1) for a given amount of energy the longer or thinner you make the barrel the more amplitude (height of muzzle flip) your going to get. In gun terms its going to be "whippy". This on it's own is fine. You can tune the wave so the muzzle is at the top of the crest and therefore moving slowest when the bullet leaves and the gun will be a one hole shooter providing the speed remains constant.
2) The frequency the barrel vibrates at (or the time it takes to go through one cycle) will remain nearly constant regardless of the energy applied. So if it takes 1 unit of time for the bullet to get to the muzzle and we then tune the barrel so that the muzzle is at the peak of the wave in 1 unit of time(as the barrel transitions from the upslope to the down slope it is momentarily motionless) all is good and we have a one hole shooter. Then we speed the projectile up from 800fps to 1000fps. Now the bullet is going to arrive at the muzzle in .8 units of time. The muzzle is still whipping through the middle part of the wave and we are going to see huge dispersion on the target. The amplitude or height of the flip is directly affected by the energy applied. So the more energy you put in during the shot cycle the higher the muzzle will flip. Thus in the previous example the dispersion will be made worse as the barrel and bullet are not only out of sync the barrel is now moving faster in the middle point of the wave. (it has to move faster in order to be at a higher peak in the same amount of time)
3) Harmonic forces will always act in opposition to static forces. In a free hanging barrel the static force is gravity pulling down thus the flip will be up and the muzzle motion will be up and down. Easy, predictable we can work with that. Now we stuff the whole arrangement in a tube. Gravity is still pulling down on the barrel plus it may be touching the tube via the locating rings and baffles in any number of spots. Who knows, are they going to touch in the same exact location every time, not likely. Which direction is the primary harmonic going to generate...who knows. Is it going to generate the same way every time...not likely.
4) Fine, we'll just clamp the sucker down with a whack load of bands, collars restraints etc. However this could in fact be the biggest disaster possible. Every time you put a hard point in a vibrating object you create a node. Nodes split the wave into two or more pieces depending on the number of nodes. The waves then travel out and back to their starting point at which point they recombine with the other piece or pieces of the original wave. Because the frequency will remain constant the speed the waves are traveling will remain constant. So if the distance each wave has to travel is different (and it will be) then the waves will be at different points in their cycles when the recombine which will create a whole new set of waves. This wave could be half or double of the original wave or anything in between. The likelihood of a chaotic "buzz" is almost guaranteed. There is a pattern in chaotic motion but you certainly can't expect it to have the muzzle where you need it to be everytime the bullet leaves. So now you've got a one hole shooter if you only score every millionth shot
Shrouds certainly have their place in the whole grand scheme of things but they are absolutely counterproductive if your primary goal is accuracy. And the more power you are trying to achieve the more that effect will be magnified.
-
Good post Sean,
Are you familiar with the the Dan Wesson PB pistols that featured the barrel floating in the shroud and pre-tentioned between the frame and shroud end via a castle type nut? Any thoughts on a pre-tensioning scheme for AGs?
Tom
-
I hope your not scarring up my bluing job with those set screws :P
I have put a few scratches in your blue which by the way it is beautiful. I have tried to blue a few things. they come out awful compared to yours. I ended up sanding off the tips of the set screws so no marks would show up.
I tested at 40 yards and it was going great. I did a few adjustments to the weights position and it was grouping great. The the POI started to shift. I could not believe it. I was shooting so well 5 minutes before. I strangled with it for a while. I take the shroud off and realized that the set screw was not tighten and the front weight started to slide backwards.
The position is very important. It only moved about 1 to 1.5 and it made a huge difference.
Sean,
I completely agree with your points. Looking back I probably should of kept the barrel a 24 inches, which I might still do, or gone with the the thicker barrel for length. Right now I have it set at 31fpe give or take. One thing that I noticed is that the barrel shoots much better when the pressure drops between 1600 and 1400. I'm regulated at 1800. There is less of a pin which might help with the harmonics.
Per your suggestion on the barrel bands. I would love to put a barrel band farther up but in my gun that is a not a good solution because the bottle floats and it is not a solid attachment. I actually tried that and was not good for my gun. It might be different for guns with air tubes.
Still testing everything. Today it was a little windy so it was hard to get good groups.
Daniel
-
Daniel,
I am very glad the weights helped like they did. From Sean's explanation it also sounds like if you change the tune (velocity) very much then the accuracy will also change and the weights might need to be moved around.
QVTom,
I am curious about the improvements that the Dan Wesson system might impart. I made a setup like that using 1" O.D. x 1/8" wall Aluminum tubing with a 45 cal barrel stretched inside of it. I never did enough playing around with it to know how much, or if any, good it did. But I am curious to know about the theory and real-world results.
Sean,
Thanks very much for that thorough explanation. The harmonics of a whippy barrel sound complex, and it sounds like the only way to almost totally eliminate them (or at least to cut the amplitude down to almost nothing) is to use a very stiff barrel, like the massive bench rest barrels we see.
Lloyd
-
Here are some groups from 40 yards. I can't remember the order I shot them but I was zeroing the scope. when I do that I shot at different targets randomly. I did have the sun on the objective lens so it was hard to get good eye alignment with the scope. It was a little windy so it was hard to tighten the groups. The number of shots per target is different from 3 to 10 shots.
If I remember correctly, the last 2 groups of five were the 3rd column top and and 3rd down.
(http://farm4.staticflickr.com/3811/12719944795_f1f23c7cc3.jpg)
-
Good post Sean,
Are you familiar with the the Dan Wesson PB pistols that featured the barrel floating in the shroud and pre-tentioned between the frame and shroud end via a castle type nut? Any thoughts on a pre-tensioning scheme for AGs?
Tom
Tom
Yes I'm a little bit familiar with technique. I think essentially whats going on is two fold.
1) the harmonic force will always act in opposition to static forces. In this case the preload on the barrel is axial so some of the harmonic energy is going to now push and pull
2)Like any two sided equation if you increase one side the other side decreases. By straining the barrel the frequency is is increasing and therefore the amplitude should decrease proportionately.
Joe McAllister built a couple of tension barrel setups. One is essentially a 2240 variant he calls Black Betty and the other is a Ruger 1022 called Trunk Monk. He has had very good results.
Personally I think the technique could get you to the level of very very good. Providing that your barrel attachment is very strong and evenly loaded. To get to Anschutz, Steyr caliber I think you would have to switch back to traditional techniques.
-
Sean,
Thanks very much for that thorough explanation. The harmonics of a whippy barrel sound complex, and it sounds like the only way to almost totally eliminate them (or at least to cut the amplitude down to almost nothing) is to use a very stiff barrel, like the massive bench rest barrels we see.
Lloyd
Lloyd
Yes going to super heavy barrels has been the traditional way to go. I have put a bit of a modern spin on that. TJ's barrels are technically liners so I have been bonding them into specially made CF tubes in the same manner I would use to reline a burned out 30-30 or similar. I've been having great luck at a tremendous weight savings
The unfinished barrel pictured weighs in at 17.4 oz complete with 3/4" OD CF jacket
The same barrel in a 18mm OD solid (smaller OD) weighs in at 45oz.
I have the jackets specially laid for maximum axial strength and then the "pretty" covering is just to get the CF look
-
It would be interesting to see if those barrel weights placed on your original (stock) barrel could solve the issues you saw from the thin/flimsy stock barrel.
Ray
-
I suspect the shroud on my .224 is going to give way to a pickle...which of course will be a barrel weight in and of itself. I am of course looking for accuracy sufficient to apply the boolit energy it is so good at delivering. Squirrels at long range and paper out past 100 yards...:) The pickle may wind up weighing too much, not to mention looking like a pickle...a distinct advantage to the shroud. I think I can live with tuning it for a specific boolit and velocity.
The weight required will also go in cycles IFF the boolit is leaving on wiggle number N, N being larger than 1. If N=1 additional mass will not help so much. Now where is my 5000 fps camera?
cheers,
Douglas
-
Sean:
I am getting a barrel from J. Gaska. At .5" dia, and me and Daniel was talking about doing CF outer liners to stiffen the barrel.
How do you bond it, and how much room do you leave for the bonding agent?
RayK:
I have done this to the stock Crosman barrel, and it took my groups from 0.19" at 25yds, to a best of 0.10 at the same distance.
I first had them all in the front just behind the shroud guide (3 collars separated by heavy rubber o-rings) then I moved one of them to about 3-4" away from the breech, and that was the ticket.
I am not going to argue with tried and true methods, but as a musician I've done it this way based upon my gut feeling that the "whip" effect will be greatly reduced if the resonance tube length is broken up in smaller but unequal sections using the collar/o-ring nodes.
-
Sean:
I am getting a barrel from J. Gaska. At .5" dia, and me and Daniel was talking about doing CF outer liners to stiffen the barrel.
How do you bond it, and how much room do you leave for the bonding agent?
There are two methods I know of that myself and every other gunsmith uses to reline PB barrels. One is Acraglas and the other is red loctite. Do not try the red loctite unless you have a press that is capable of driving a barrel home in a couple of seconds.
For the Acraglas method. Use the traditional thin formula as opposed to the butter. Put a tiny chamfer on the inside diameter of the CF to act as a funnel. Roughen the barrel lightly with 180 grit and give it wipe with high solvent. or brakleen. Coat the barrel entirely in acraglas and wait a few minutes for the bubbles to rise. Then using a twisting motion shove the jacket on. I allow no clearance. The liners come in at .498-499 and the ID of the CF is dead on .500. So 99.9% of the acraglas you put on will be squeegeed off but thats exactly what you want.
As I said previously the CF I'm using is custom made for my application. Off the shelf will not give as much stiffness. Use a UD constructed tube as opposed to the pretty twill to get the most stiffness.
-
oh and always be cautiously diligent with CF.....mask and HEPA dust extraction are a must when cutting or sanding. The microscopic needles are as bad or worse than asbestos
-
Thanks!, yes UD is the only version I would consider to get max stiffness.
Is Acraglas an epoxy? (I've done racecar parts in CF before, so I am used to to working with various bonding agents)
T
-
it's a "gunsmith" epoxy. Originally made for bedding. It's been in use for longer than I have been alive. It has an incredibly low shrinkage rate which is what you need in this type of application
http://www.brownells.com/gunsmith-tools-supplies/stock-work-finishing/stock-bedding-adhesives/acraglas--prod1033.aspx (http://www.brownells.com/gunsmith-tools-supplies/stock-work-finishing/stock-bedding-adhesives/acraglas--prod1033.aspx)
-
Ok, that make sense, in the applications I've been doing, we don't worry unless the parts are very wide or long (shrinkage wise) so we just make the mold a little larger to allow for that. Cool, new stuff to learn about!!!
T
-
Ps. It looks like its a better deal buying it from Amazon.
http://www.amazon.com/Brownell-081003002-Brownells-Acraglas-081-003-002/dp/B0000AVEH7/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1393174601&sr=1-1&keywords=Acraglas (http://www.amazon.com/Brownell-081003002-Brownells-Acraglas-081-003-002/dp/B0000AVEH7/ref=sr_1_1?s=sporting-goods&ie=UTF8&qid=1393174601&sr=1-1&keywords=Acraglas)
-
Hahaha...no comment
Lets just say me and Brownells haven't been getting along too well lately. I love companies that buy out the competition, make all their products proprietary then go out of stock for months at a time or simply refuse to sell them to canadians etc.....because they wont buy the appropriate shipping box
-
Yah, I hear you on that one.
I am sure there is some alternatives to this epoxy as more and more industries rely on accurate CF parts, such as camera and film equipment (I do photography also)
T
-
Sadly my problems aren't epoxy. Its the fact that they made every decent bluing product ever made proprietary ....tough to carry on a gunsmithing business without professional grade bluing products.
-
Bummer...let's call nickel plating an upgrade:-)