Wife's new AR & buffer ???'s

[MachIVshooter]

So, I've been trying to get one together for her on one of my DSA lowers for months now, and really wanted to do a lightweight middy, but everyone, everywhere has been perpetually out of stock on those (and everything else). So today we stopped by my buddy's shop, and he had a couple of Rguns uppers, one green and one gold. After himming and hawing a bit, she decided she liked the gold, so we grabbed that, an LPK and the only buffer/stock package he had, which is an el cheapo. So here's the assembled rifle:



I'll probably have the barrel cut and do a permanent flash hider, as I can't stand the 16" M-4gery look, but if I was going to get her rifle done anytime soon, this was pretty much the only way. She likes it, though.

Anywho, I'll be ordering a Magpul CTR stock and a new buffer/tube/spring soon, but my question is this:

This cheapie buffer tube was bored short, and wouldn't allow the bolt full travel (BHO inop). So, I shortened the buffer (retained all 3 weights) and clipped 4 coils, then used washers in the bottom of the tube to bring it back to where the buffer stops the BCG about 3/16" before the gas key hits the extension housing, and allowing the bolt to go about the same 3/16" past the BHO. We may not even get to the range before I get the new buffer & stock, but I wanted the rifle GTG in case we do, and this combo was cheap enough that I don't really care if it gets scrapped. Does anyone see a problem with such a mod? I've never shortened buffers and springs, but I see no reason this wouldn't be OK, since I spaced it enough to prevent gas key impact on the lower.

 

[meanmrmustard]

The aesthetic lady in me thinks that be oogly!

But, looks like a nice, solid build. I hope she enjoys it!

Have you done this mod before?

 

[MachIVshooter]

No one else has any thoughts on the buffer, huh?

Have you done this mod before?

No, that's why I'm seeking input. I've heard of it, but never tried before.

 

[taliv]

Sorry I couldn't tell from your description what you were actually doing. Or why you wouldn't just replace the defective part

 

[MachIVshooter]

What I did was shorten 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. 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)

why you wouldn't just replace the defective part

We plan to, I'm just asking the experts if there is any problem with running it this way until replacements arrive. I personally don't see that it would be, but I've never shortened a buffer & spring before, so figured I'd see if anyone else has.

 

[Quentin]

I would say there are lots of problems running it this way. And I'd avoid firing it until you get quality replacement parts.

 

[ApacheCoTodd]

Shortened the buffer how and where on the buffer?

I've stubbed buffers and springs before for odd applications but I don't think I've ever needed to cope with an incorrectly spec-ed (internal depth) receiver extension. If I were to guess at outa spec relative to your symptoms, my experience has been in out of spec or incorrect recoil springs way more often than extension tubes being wrong.

Also, I'm assuming that one end of your recoil spring no longer has a multi-coil seat but would rather have a cut off end. HTis can be problematic regardless of which way round you insert the spring.

Beyond that, you've altered the spring rate and depending upon cycling components and their own specs, that could present an issue at some point if not now.

 

[taliv]

You know you're not supposed to screw the receiver extension all the way into the lower right?

Are you sure you have the right parts? Carbine vs rifle length?

 

[MachIVshooter]

Shortened the buffer how and where on the buffer?

Drove the roll pin out, cut off 1/2 of the buffer, drilled a new hole, put the weights back in and reinstalled the poly bumper.

I've stubbed buffers and springs before for odd applications but I don't think I've ever needed to cope with an incorrectly spec-ed (internal depth) receiver extension. If I were to guess at outa spec relative to your symptoms, my experience has been in out of spec or incorrect recoil springs way more often than extension tubes being wrong.

The spring and buffer from this kit worked fine in my Armalite M15A2C, and conversely, the spring and buffer from my Armalite did not remedy the problem when installed in the tube of the new rifle. The tube itself was bored 1/2" shallower than the one on my Armalite.

Also, I'm assuming that one end of your recoil spring no longer has a multi-coil seat but would rather have a cut off end. HTis can be problematic regardless of which way round you insert the spring.

Correct. I have no way of creating a multi-coil seat without heating, which would obviously affect spring rate.

Beyond that, you've altered the spring rate and depending upon cycling components and their own specs, that could present an issue at some point if not now.

Whether the spring rate or the lack of inertia from the buffer weights being tight in the buffer, yes, we had failures to return to battery. A light push (litterally just a couple of pounds of force) on the FA would close it the last ~1/8".

You know you're not supposed to screw the receiver extension all the way into the lower right?

Just far enough to keep the buffer detent pin from flying out,yes.

Are you sure you have the right parts? Carbine vs rifle length?

Yes. This is the kit:



http://www.amazon.com/Tactical-Stealth-Telescoping-Collapsible-Position/dp/B0085YBAM0

 

[Davek1977]

n/m

 

[Okiegunner]

Question, OK?

I am very new to the AR.

I am adding the "auto" BCM, BCG to my rifle. Do I need to also add the H or H2 buffer? I do not know.

Thanks much...

 

[MistWolf]

Which buffer you'll need depends on how the upper is configured. If you get a BCM upper with a 16" barrel with the mid-length gas system and are using a carbine length receiver extension, either the carbine weight buffer or the H weight buffer with a standard carbine spring would be a good place to start. If you get a BCM 16" upper with the carbine length gas system, start with the H buffer

 

[Okiegunner]

MistWolf...

Much thanks. H Buffer it is then. Its, for some reason, been hard to get a straight answer from a lot of folks. Maybe do to much differing opinions.

I appreciate the answer.