AR buffer question

[MachIVshooter]

OK, so I just wans't getting any thoughts in my other thread (http://www.thehighroad.org/showthread.php?t=678406), so I decided to start a new one.

Finally got the wife's AR together, but the only stock/buffer combo my LGS had was a cheapie, and the tube was bored short. So I shortened the buffer by 1/2" and clipped 4 coils off the spring so that the bolt could travel far enough, then used steel fender washers (exact OD for the buffer tube, #12 screw hole) at the rear of the tube to shim up until I had 3/16" clearance between gas key and extension housing with the buffer contacting the shims (with spring removed). All three weights in the buffer were retained, though I had to remove 2 of the 3 rubber pads (weights are now tight in the buffer).

So, the question is, do any of the AR experts see a problem with running it this way for a little while?

 

[Quentin]

Same answer that I posted in your other thread. I see lots of problems. Don't shoot it, put in quality replacement parts.

 

[madcratebuilder]

Same answer that I posted in your other thread. I see lots of problems. Don't shoot it, put in quality replacement parts.

+10

For the AR buffer to do it's job right there has to be room of the discs to move, that's how it gets the buffering effect.

 

[madcratebuilder]

It doubled

 

[Z-Michigan]

I wouldn't shoot it either. A decent buffer tube is $20, or $30-40 for a true mil-spec tube. I can't tell if you permanently altered the buffer as well, but it sounds like it, and I would get a proper buffer as well.

Why risk $100s worth of other parts to see if your jerry-rigged setup will work on a temporary basis?

 

[MistWolf]

My thoughts are that there is a problem with parts incompatibility along with a lack of knowledge and experience in the attempt to deal with it. If there is not enough or too much travel for the BCG inside the receiver extension (the correct term for what is being called a "buffer tube") severe damage can occur to the rifle when fired.

Best advice I can give you is to NOT shoot the rifle until you get the correct parts and have a knowledgeable person help you with the installation

 

[EMS_92]

What Quentin said.

 

[MachIVshooter]

If there is not enough or too much travel for the BCG inside the receiver extension (the correct term for what is being called a "buffer tube") severe damage can occur to the rifle when fired.

Hence the reason I altered lengths and measured fore and aft travel. I'd love to hear what "severe damage" you believe could occur when the modified combination was set with the same rearward travel as other rifles that did not have a defective tube (it was measured against my bone stock and stone axe reliable Armalite M15A2C).

And buffer tube is the more common term, whether you deem it laymen or not. Try the two terms in an internet search and see which one gives more AR parts than trailer hitches.

a lack of knowledge and experience in the attempt to deal with it..........have a knowledgeable person help you with the installation

How condescending. It's a matter of not knowing if there is or isn't a way to make a defective part work properly before trying it, and simply seeing if anyone else has. I've hand built entire guns from raw steel, and I can assemble an AR in my sleep. I've just never encountered a short buffer tube. My other option without buying parts was to bore the tube deeper, but I don't have long drill bits that large in diameter. Such a bit would cost more than the tube is worth, has no other use for me, and would take as long to receive as the new tube.

We fired it on Sunday, and no damage occurred. It did have some failures to fully return to battery, I suspect a result of the buffer weights not being able to move and create the tiny amount of force that was necessary to push the bolt forward the last 1/8". Maybe a spring power issue, but I read plenty of accounts of clipping coils to alter recoil impulse and deal with short stroke issues in SBR's, so unless the spring is just crap (entirely possible), I don't think the 4 coils I clipped matter.

I'm sure I could make it work by replacing the steel buffer weights with shorter molybdenum pieces of the same weight that would allow the ~1/4" of travel within the buffer, and perhaps with an extra power spring. However, the new tube, spring and buffer should be here this week, so it'll be a non-issue, and now others can know that modifying the parts in this way won't cause damage but may cause malfunctions.

 

[WinThePennant]

I like to tinker with ARs. But, I do so with parts combinations that I know will work.

To me, this doesn't sound like tinkering. It sounds like an accident waiting to happen.

The part of the AR you are tinkering with is probably one of the least expensive areas and there's no reason to not have high quality stuff. Personally, I like VLTOR buffer tubes the best. BCM is good, but I like VLTOR's finish. A top quality buffer tube is only $40 - $50.

 

[kwelz]

If you we're just going to shoot it after you Bubbad it no matter what was said then why did you even ask in the first place?

What you did is unsafe bordering on negligent. Good for you that it didn't fail in the few rounds you have already fired through it. That doesn't mean you did good.

 

[X-Rap]

Not saying the OP is right or wrong but the replies cause me to wonder what someone like JMB, David Williams, John Garand, Eugene Stoner would have gotten as responses to some of their questions.
I'm also not saying that the OP is even close to the above men in design intellect but that is because I don't know him.
Necessity is the mother of invention right? Having the abilities to think through a problem and get any machine going may be the bubba way to some but it used to be a respected talent.

 

[MachIVshooter]

If you we're just going to shoot it after you Bubbad it no matter what was said then why did you even ask in the first place?

Opinions. I alread had one, and had gathered others reading over a number of different archived threads in other boards, most of them from folks playing with NFA stuff that had issues with dwell time due to barrel length or use of supressors. Some of them had even shortened the tube itself.

What I was seeking was the words of someone with some real experience in custom alterations of AR platforms, not the unfounded and scathing opinions of a few folks who have (maybe) slapped a few LPK's into a stripped receiver and plopped an upper on. That's why I said experts, not guys who once put together a rifle kit and now consider themselves professional gunsmiths.

What you did is unsafe bordering on negligent.

Please. We're not talking about trying to weld lugs back on a bolt here. The worst that could possibly happen would have been the result of too much BCG travel shearing the gas key screws and/or damaging the extension housing & buffer tube. I also clearly explained that rearward BCG travel was carefully checked and adjusted following the mod, so this wasn't even a possibility.

If you can show me that you have a background lending credence to your accusation, I'm all ears. But I really don't think you can factually articulate just what is so dangerous and negligent about what I did.

Buncha naysayers and scardy cats, I say. If no one ever tried something that was previously untested or unconvetional, we'd still be throwing speers.

I'm also not saying that the OP is even close to the above men in design intellect but that is because I don't know him.

I know you didn't mean for that to come across as insulting, but it was a little. FYI, my IQ was professionally tested at 144.

 

[mshootnit]

I would order a stock kit and start over.

 

[MachIVshooter]

I would order a stock kit and start over.

A new buffer kit (don't know which one he's bringing in yet) and Magpul CTR were ordered Monday morning.

This was a temporary solution that didn't work out on the first try and isn't worth pursuing further. I just felt it was worth a shot, since I had a whopping $35 into that stock & buffer combo. Better parts would have been bought in the first place, but as I said, this was all he had on the shelf, and he gave it to me at cost. He felt bad that it didn't work and is giving me the new buffer kit and CTR at cost as well (way less than any internet source I've found at $55 for the stock and $40 for the buffer kit).

 

[MistWolf]

Hence the reason I altered lengths and measured fore and aft travel. I'd love to hear what "severe damage" you believe could occur when the modified combination was set with the same rearward travel as other rifles that did not have a defective tube (it was measured against my bone stock and stone axe reliable Armalite M15A2C).

That's assuming you got the travel right. What is the proper depth for a carbine receiver extension? How much shorter was the defective part? Was it really the receiver extension that was out of spec, or was it the buffer? Maybe you got an A5 buffer by mistake. The original post doesn't touch on any of these questions.

ARs have been damaged enough to render the upper receiver unserviceable and the rifle inoperable by using carbine buffers in rifle length receiver extensions by allowing too much travel by the BCG

And buffer tube is the more common term, whether you deem it laymen or not. Try the two terms in an internet search and see which one gives more AR parts than trailer hitches.

Words are important. Your original post gives the impression you were winging with little actual experience on the parts being modified. Calling the receiver extension reinforces that impression

How condescending.

Not at all. Simply calling it the way I see it and spoke plainly

It's a matter of not knowing if there is or isn't a way to make a defective part work properly before trying it, and simply seeing if anyone else has. I've hand built entire guns from raw steel, and I can assemble an AR in my sleep. I've just never encountered a short buffer tube. My other option without buying parts was to bore the tube deeper, but I don't have long drill bits that large in diameter. Such a bit would cost more than the tube is worth, has no other use for me, and would take as long to receive as the new tube.

We fired it on Sunday, and no damage occurred. It did have some failures to fully return to battery, I suspect a result of the buffer weights not being able to move and create the tiny amount of force that was necessary to push the bolt forward the last 1/8". Maybe a spring power issue, but I read plenty of accounts of clipping coils to alter recoil impulse and deal with short stroke issues in SBR's, so unless the spring is just crap (entirely possible), I don't think the 4 coils I clipped matter.

I'm sure I could make it work by replacing the steel buffer weights with shorter molybdenum pieces of the same weight that would allow the ~1/4" of travel within the buffer, and perhaps with an extra power spring. However, the new tube, spring and buffer should be here this week, so it'll be a non-issue, and now others can know that modifying the parts in this way won't cause damage but may cause malfunctions.

The space in the buffer isn't to help seat the BCG. It's to lessen the shock of the BCG as it reaches the end of it's travel. The problem lies with your spring. Cutting the coils reduced the amount of energy the spring can store and may now be under powered. (I was incorrect earlier when I said cutting coils increases spring rate. I was thinking of something else.) Another problem may be that the buffer weight has changed.

It isn't about being a naysayer or being a scaredy-cat. I do plenty of experimenting on my own and have broken plenty of parts, but on machines that are test beds. If you understand the possible consequences, tinker away. Your original post not sound like you did.

It's good that your gunstore guy is taking care of you. It's great to find a place that gives good customer service

 

[MachIVshooter]

How much shorter was the defective part?

.533" shorter inside than the one on my M15 carbine, which is the only other tube I had on hand to measure. Incidentally, the outside length of the kit extension is longer than the one in my M15 by about 3/16". There's a big hunk of aluminum on the back of that thing with just the small drainage hole through it.

Was it really the receiver extension that was out of spec, or was it the buffer?

Well, the buffer was practically identical to the one in the Armalite carbine, and as I said, the buffer and spring from the kit worked fine in the Armalite tube. The Armalite buffer & spring did not work in the tube from that kit.

In short, yes, I'm sure it is an out of spec tube.

Cutting the coils reduced the amount of energy the spring can store and may now be under powered.

Yes, I know. They were cut out of necessity, as even with the shortened buffer, putting in the full lengh spring supplied with the kit still stopped the BCG short. I clipped coils until the buffer was able to contact the bottom of the tube, then clipped another 1/2 coil to allow for compression of the poly bumber before spring stacking.

If you understand the possible consequences, tinker away.

I do. I'm well aware that just haphazardly cutting things could result in excessive BCG travel that could damage gas key, bolt carrier, extension housing, tube and possibly the upper if fired with a damaged BCG. But careful measuring and shimming precluded this possibility, so I was just taking a gamble that rendered a $35 kit unreturnable. Oh well.

No damage/undue wear to any parts occurred in the two mags we fired. It was just a single shot rifle half the time.

It's good that your gunstore guy is taking care of you. It's great to find a place that gives good customer service

Yes, it is. He also happens to be a good friend, but I don't ask him for discounts. He gives them to me anyway, and I generally throw in extra cash for a total that is somewhere between cost and normal retail. However, he takes care of other customers in a way that few shops do.