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Posted: 5/6/2010 8:48:43 PM EDT
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Am having terrible trouble trying to get this thing to work.
It tends to suffer from light primer hits as a result of the bolt carrier not being completely forward after chambering a round. The hammer then hits the carrier which soaks up enough energy that it doesn't hit the firing pin hard enough to set the primer off. This can happen on the first round or any subsequent round. The gun does cycle, eject and load the next round just fine but I think the carrier is bouncing due to the lack of a buffer or anti-bounce weights. Anyone know how to get this bad boy working? http://members.shaw.ca/cronhelm/Images/SPEXPDW.jpg |
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As a SWAG I'd say that the reduced spring and buffer from that short tube setup just aren't sufficient for reliable operation. Sounds like you aren't getting enough spring force to fully cycle the action closed.
Put a standard length pistol buffer tube on there, with a standard carbine recoil spring and (probably) a heavier buffer. |
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what is that muzzle device?
What is that thing you have on the bottom of the hand guard? I guess you are running a shortened carrier like on there bushmaster pistol type guns or what? To stop bolt (carrier) bounce you either need to decrease the velocity at which the carrier travels into battery and/or increase the weight of the buffer weight inside the buffer assembly. If the latter is not an option you could experiment w/ cutting coils out of the action spring, but then you turn a 2 dimensional problem into a three dimensional one. It would be simpler & more robust to just use a carbine or rifle length tube & parts. At least w/ that you can make a cheekweld &/or shoulder the weapon. |
THe hammer is not supposed to put the gun in battery. It should already be in battery before the hammer falls. You should not want the hammer to fall at all unless the gun is in battery. Geometry probably make it impossible here, but worse case scenario w/ dropping a hammer on a gun that is not i batter is a kaboom 
Also, FWIW, I did have a professional ordinance pistol. I did have to polish the chamber so mil case woulnd' tget stuck in the chamber, but after that, it ran like a top. Was a shit load of fun bump firing. Was my favoirte range toy ever. It did have the shortened carrier & tube. |
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Hey, if you want to ditch that GSE tube, I AM working on a buffer system, using a standard carrier, that seems to be working, but I've been having to chop tubes for the prototype. I'd be willing to buy it off you [just the tube] if you go with a standard carbine/pistol tube.
I'd rather not pay $80 for the full GSE system if I'm just going to toss the guts and keep the tube. Oh, and what I am working on doesn't require you to pull the cap off the back to remove the springs before disassembly. 
FYI, you might not want to have that Magpul AFG on there...just sayin
The problem you are having with bolt bounce is common with the GSE/Old M1S shorty buffer systems, like the one it looks like you have. Easiest solution is to go to the carbine tube as suggested above. |
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As a SWAG I'd say that the reduced spring and buffer from that short tube setup just aren't sufficient for reliable operation. Sounds like you aren't getting enough spring force to fully cycle the action closed.
Thats what we thought at first so we shimmed up the spring and the problem actually got worse. When you chamber a round you can actually see the carrier bounce back a bit. Put a standard length pistol buffer tube on there, with a standard carbine recoil spring and (probably) a heavier buffer.
I would like to get it to run with the reduced length buffer tube. what is that muzzle device?
What is that thing you have on the bottom of the hand guard? The muzzle device is something I designed and my buddy built. http://members.shaw.ca/cronhelm/Images/300Fireball3.jpg I guess you are running a shortened carrier like on there bushmaster pistol type guns or what?
No the carrier is full length but there is no buffer. And I think that is the source of the problem. Buffers incorporate an anti-bounce mechanism which is what this system lacks. THe hammer is not supposed to put the gun in battery. It should already be in battery before the hammer falls. You should not want the hammer to fall at all unless the gun is in battery. Geometry probably make it impossible here, but worse case scenario w/ dropping a hammer on a gun that is not i batter is a kaboom
The hammer falling and the carrier being out of battery are totally unconnected events. The AR rifle has no mechanism to stop the hammer release when the carrier is out of battery. The geometry of the carrier prevents the hammer hitting the firing pin when the carrier is out of battery. In this case the carrier gets hit by the hammer which drives it forward back into battery. This causes a soft primer hit which causes a misfire. And all this is what I am trying to solve. |
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Hey, if you want to ditch that GSE tube, I AM working on a buffer system, using a standard carrier, that seems to be working, but I've been having to chop tubes for the prototype. I'd be willing to buy it off you [just the tube] if you go with a standard carbine/pistol tube.
I'd rather not pay $80 for the full GSE system if I'm just going to toss the guts and keep the tube. I'd like to keep the short buffer tube but am def interested in the system you are working on. Anything to get this thing to work would be appreciated. Oh, and what I am working on doesn't require you to pull the cap off the back to remove the springs before disassembly.
Actually don't mind it so much other than it takes a minute or two. FYI, you might not want to have that Magpul AFG on there...just sayin
K I'll bite, why not? |
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I don't have all the bugs and tuning out, and I only have the prototype parts at the moment....and I want to patent the sucker if it survives torture testing over at Red Jacket Firearms on one of Will's FA lowers, otherwise I'd info dump you on it. So far though, I have pretty much cut the tube length down a couple inches...got it down to around m231 length with a standard carrier.
Letcha know when I get to a point where I won't be shooting myself in the foot to tell you more. Edit: The concept was for a true M231 style tube and stock set up, but without the 231 style stock, it works as a short "pistol" buffer too. |
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Since you have a machist buddy who made that linear comp/pig type thing, why dont' you try to have him come up w/ a way to make the back of the carrier hold some fine lead shot captive, sort of making the buffer intergral to the bolt carrier. That way you don't have to use a half lenght carrier. Or you could use wieght & pads stacked just like in a buffer.
You really can't get an AR to run right w/o a buffer. increased carrier velocity will of course increase you amount of bolt bounce. I gather that the OP has a grasp of things, but for some of the readers of this thread: -There is no "Buffer spring". That spring is not designed to buffer the gun's recoil, it is the action spring which cycles the weapon (in conjunction w/ the gas system). -The "buffer" has nothing to do w/ buffering recoil for the shooter, if buffers bolt bounce. |
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why are we all assuming that the gun pictured is not a registered AOW?
I heard that magpul was tryign to get some clarification from the ATF about use of the AFG on a pistol. Was there ever any clarification about it? Maybe someone can come out w/ a heavily tapered handguard to approximate the ergos of the AFG. |
| Maybe so...I think most of us here just want to make sure our fellow enthusists don't get jammed up over a stupid "gun rag" mistake [yes, even the gun rags do stuff like that to make the gun "look cool" on the cover, not realizing they just broke federal statutes] |
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well the normal car h buffer works fine for me ––-but to answer YOUR question the best thing i can think of is the CWS system by david tubb " carrier weight system"
http://www.superiorshootingsystems.com you could modify it by cutting the tungsten weight in half, then closing the open end of the steel "plug" that holds the tungsten by welding. thereby creating a mini buffer inside the back of the carrier that will allow the tungsten weight to reciprocate and provide the inertia to keep the bolt shut. |
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Since you have a machist buddy who made that linear comp/pig type thing, why dont' you try to have him come up w/ a way to make the back of the carrier hold some fine lead shot captive, sort of making the buffer intergral to the bolt carrier. That way you don't have to use a half lenght carrier. Or you could use wieght & pads stacked just like in a buffer.
You really can't get an AR to run right w/o a buffer. Yes, that is the conclusion we are quickly coming to. The only fly in the ointment is that the recoil spring arrangement uses a steel collar that fits inside the back end of the carrier which takes up the space where we'd have to install the buffer weight. It is kinda a problem trying to fit all those bits into the same place. increased carrier velocity will of course increase you amount of bolt bounce.
And that was exactly what happened when we shimmed up the recoil spring. but to answer YOUR question the best thing i can think of is the CWS system by david tubb " carrier weight system"
you could modify it by cutting the tungsten weight in half, then closing the open end of the steel "plug" that holds the tungsten by welding. thereby creating a mini buffer inside the back of the carrier that will allow the tungsten weight to reciprocate and provide the inertia to keep the bolt shut. And that is the best suggestion I have heard yet. Kudo's to you sir. :) I actually have one of those Tubb Carrier Weight Systems on hand. I will have to have a closer look at it and see how it could be adapted to fit both the moving weight and the end of the recoil spring. |
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Quoted:
Maybe so...I think most of us here just want to make sure our fellow enthusists don't get jammed up over a stupid "gun rag" mistake [yes, even the gun rags do stuff like that to make the gun "look cool" on the cover, not realizing they just broke federal statutes] I wouldn't want to see a fellow gun enthusiast go to prison over some ridiculous ATF rule he accidentally broke. However, if I ever got called for jury duty on an NFA trial, I already know what the verdict is going to be...Not Guilty! |
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So I think we have cracked it.
We added an anti-bounce weight to the bolt carrier and the thing ran perfectly first time. I'd like to do a bit more testing and tuning but it seems the basic system is sound. We had to modify the carrier somewhat and make a few small parts in order to fit everything into the limited space at the back of the carrier. I LOVE IT when a plan works out. 
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Quoted: So I think we have cracked it. We added an anti-bounce weight to the bolt carrier and the thing ran perfectly first time. I'd like to do a bit more testing and tuning but it seems the basic system is sound. We had to modify the carrier somewhat and make a few small parts in order to fit everything into the limited space at the back of the carrier. I LOVE IT when a plan works out. You shortened the carrier? Then attached the tungsten weight to it? I'm thinking of (haven't looked at my Tubb's tungsten yet) using the tungsten in the buffer, and shortening the carrier. |
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Quoted:
So I think we have cracked it.
We added an anti-bounce weight to the bolt carrier and the thing ran perfectly first time. I'd like to do a bit more testing and tuning but it seems the basic system is sound. We had to modify the carrier somewhat and make a few small parts in order to fit everything into the limited space at the back of the carrier. I LOVE IT when a plan works out. That's good news. I'd like to see pictures of your modification. Thanks. |
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You shortened the carrier? Then attached the tungsten weight to it?
Nope, carrier is still the same length. We turned down the OD of the rear portion of the carrier and then made a sliding weight that fits over the outside of the turned down portion. Then we remade the spring retaining collar with a larger flange to retain the sliding weight. So it all fits into the same space as before but has a sliding weight over the rear portion of the carrier which is captured by the spring retainer. This works exactly the same as a normal buffer only the weight is on the outside of the carrier rather than being inside the buffer. If the weather cooperates this weekend I will try to get out and video it in operation. |
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Quoted:
You shortened the carrier? Then attached the tungsten weight to it?
Nope, carrier is still the same length. We turned down the OD of the rear portion of the carrier and then made a sliding weight that fits over the outside of the turned down portion. Then we remade the spring retaining collar with a larger flange to retain the sliding weight. So it all fits into the same space as before but has a sliding weight over the rear portion of the carrier which is captured by the spring retainer. This works exactly the same as a normal buffer only the weight is on the outside of the carrier rather than being inside the buffer. If the weather cooperates this weekend I will try to get out and video it in operation. I have been making the stainless inserts that hold tungsten for the inside of the stock carrier . 
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I have been making the stainless inserts that hold tungsten for the inside of the stock carrier
But that wouldn't work with the really short buffer tube because there is a spring retainer that sits inside the back end of the carrier where you have installed your tungsten weight. I looked at extending that retainer forward and installing a weight in th front of it but you can't do that either cause it would get in the way of the hammer travel. And you can't appreciably shorten the spring retainer either or the small diameter 1911 type spring would bend and bind under compression. The only place I could find any available space for a moveable weight was on the outside of the carrier. Once I figured out how to fit everything into the available space, it was actually quite easy to make the bits. Anyone with fairly basic machining skills and access to a lathe could do this conversion. |
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Quoted:
Quoted:
You shortened the carrier? Then attached the tungsten weight to it?
Nope, carrier is still the same length. We turned down the OD of the rear portion of the carrier and then made a sliding weight that fits over the outside of the turned down portion. Then we remade the spring retaining collar with a larger flange to retain the sliding weight. So it all fits into the same space as before but has a sliding weight over the rear portion of the carrier which is captured by the spring retainer. This works exactly the same as a normal buffer only the weight is on the outside of the carrier rather than being inside the buffer. If the weather cooperates this weekend I will try to get out and video it in operation. I have been making the stainless inserts that hold tungsten for the inside of the stock carrier . http://i197.photobucket.com/albums/aa166/redtazdog/AR9mmstainlesstungweightbuffer12.jpg What is that it doesnt look like Tubb's CWS ? I am interested...link? |
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Quoted:
I have been making the stainless inserts that hold tungsten for the inside of the stock carrier
But that wouldn't work with the really short buffer tube because there is a spring retainer that sits inside the back end of the carrier where you have installed your tungsten weight. I looked at extending that retainer forward and installing a weight in th front of it but you can't do that either cause it would get in the way of the hammer travel. And you can't appreciably shorten the spring retainer either or the small diameter 1911 type spring would bend and bind under compression. The only place I could find any available space for a moveable weight was on the outside of the carrier. Once I figured out how to fit everything into the available space, it was actually quite easy to make the bits. Anyone with fairly basic machining skills and access to a lathe could do this conversion. . With my mill and lathe , I feel I could make anything work
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Well I have a mill and a lathe as well but that doesn't change the fact there is a limited amount of space available at the back end of an AR bolt carrier. The hammer has to have room to swing and the recoil spring has to have a space to compress into without bending or binding. In the current setup the tip of the recoil spring is quite close to the arc of the hammer swing. So that doesn't leave much room to install anything else into that space. Which is why we went to a weight on the outside of the bolt carrier.
I suppose with extensive reworking and machine time pretty much anything could be made to work but we were looking for a simple and easy solution that wouldn't cost a fortune in time and money to make work. |
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Here are some pics of what we did.
The two parts we made and the modification made to the back end of the carrier. We used a FA carrier but this could be done on a SA carrier as well. http://members.shaw.ca/cronhelm/Images/PistolBufferWeight1.jpg The spring retainer in place. http://members.shaw.ca/cronhelm/Images/PistolBufferWeight2.jpg All the bits in place. http://members.shaw.ca/cronhelm/Images/PistolBufferWeight3.jpg |
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