The right 10mm AR buffer

[John A.]

OK, I know there's a bunch of different "right" answers all depending on which 10mm AR style action you have.

For instance, the banshee uses a 3.5oz buffer the best that I can recall off the top of my head with their rotary delay bolt.  It's supposed to be one of the better designs out there.  Trouble is, cmmg is really proud of them and grabbing one for under $1500 is almost unheard of, which put it well outside of what I wanted to spend on a little whitetail carbine.

I'm not sure exactly what the buffer weighs on the DI guns?

But, for the blowback 10mm guns, it takes a beefy 10oz bolt.

But, the thing is, nobody makes a rifle length heavy buffer for those of us who may want a rifle stock or at least a rifle length tube.  So, when life hands you lemons, you make lemonade.

I'm waiting on an A1 buffer tube and a piece of foam to cover the tube, much like the old Ace skeleton stocks that were so popular during the ban years.  Truth is, I still love that style.  Especially while hunting.  The foam feels so much better on those cold snowy and frosty days when you look down the sights at a whitetail.  Plus, I always thought that it quitened the "sproing" sound down better too.  Though I'm going to be using a flat coil chrome silicone tubbs/superior shooting 308 cal spring in mine since that's arguably the heaviest spring weight you can probably get that I know of.

In the years since the AWB, Ace has sold to doublestar AR manufacturing and they now have what they call an ultralight stock.  Which is essentially a tube with a piece of foam and a clamp on butt plate. Here's a link to how they look and mine will be very similar.  https://www.midwayusa.com/product/101784526

Well, I have been thinking about the gov trying to ban braces and stuff calling them stocks, so since I have an extra laying around collecting dust,  I decided that I'm going to use a gearhead tailhook brace on the end of the buffer tube to legitimately create a butt plate.  I can add a couple of pics of that later after the tube and foam is delivered if anyone is interested in seeing it, but that leaves a dilemma in regards to the buffer.

You can't use a carbine length buffer in a rifle length buffer tube.  Carbine buffers are too short and would cause the bolt to collide into the rear of the receiver and would destroy something in very short order.

And unfortunately, the market isn't big enough that you can find a super heavyweight buffer in rifle length either.

So, maybe the solution is to add an extension onto the heavy carbine buffer and bring it to proper length?



OK.  That was easy enough.  It was just a 1.8 inch extension and a couple of holes to put in some roll pins and hold everything back together,  but what about adding the ledge for the buffer spring?  After some thinking about it, I simply added a 1" OD piece of aluminum and bored it out to 3/4" ID and slid it into place.

While it isn't as nice as a machined contour, it will give plenty of a shoulder for the buffer spring to seat against.



My sleeve also sits back about 1/2" further than the OEM rifle length buffer, but I figure that may add a little to the pre-load on the spring keeping the bolt closed a little longer.

And if I don't like it, I could always slide it off the buffer and shorten it down to where the OEM location is.  No big deal.

Another purpose for wanting to swap out from a collapsible stock to a rifle is that while the gun is cycling perfectly now, it is ejecting empty cases into the next zip code.  Considering that I'm loading to max, I'm still trying to keep it from launching the brass as far.

So, this may help a little?  I don't know, but it at least shouldn't hurt it any either.

I also checked the weight after adding the extensions.  12.35oz

So,  that too should help some.

Truth is, I could bore out the extension that I made and could insert more buffer weights inside of it if I were really inclined to.  But I don't think I will at this time.  I'd like to shoot it a bit before deciding whether to do that or not.

I'll let you guys know how it does after I get to shoot it, but I'm hoping that the ejection is more mild. 

I just thought some of you may be interested in the buffer mod because I'm sure I'm not the only person out there that would like to use a rifle stock, or at least a rifle length stock and add to the LOP to get it more comfortable on the shoulder where your cheekweld is concerned.  And the extra travel, may make it more mild and pleasant to shoot too?  I know that I prefer shooting my 20 inch AR's more than the shortest ones.

I don't think the 10mm is bad now in the recoil department.  I'm not implying that it is.  I grew up shooting shotguns until I had nice purple and green bruises on my shoulder.  10mm is nothing compared to that.

But, I do appreciate the longer length of pull though.  It just feels better to me.

Anyway, just thought I'd share.

[John A.]

Still not sure how many folks are making 10mm AR's these days given that so many companies are making factory built carbines right now, but since the forum went dark, I again changed my buffer layout and thought I'd share for any of you that may be going down that path.

I made it similar to how the armaspec stealth buffer is but obviously I had to make multiple changes to the design to work in a PCC.

For starters, my 10mm AR bolt (direct blowback) has a weight added to the rear of it.  This prevents the armaspec stealth buffer from being compatible at all with PCC bolts because there's no way for the buffer spring guide rod to protrude up inside the rear of the bolt as it cycles. So this would preclude me from using one of theirs even if I wanted to.

But since I am using a longer rifle length buffer tube, that gives me more room necessary for everything to work together.  Instead of the guide rod needing to protrude into the bolt, I made my guide rod so it only protrudes up into the longer buffer and doesn't need to fit inside of the rear of the bolt at all.

Here's a picture of how that looks while the buffer is fully compressed.  As you see, the front of the guide rod stays inside the buffer weight.



I made the buffer from 12L14 steel.  That grade of steel has lead added to the mix to not only make it easier to machine but is a little heavier as well.  This one was just short of 11 ounces.



I had initially considered using another standard AR buffer spring on the outside circumference of the zytel rod and the rear of the buffer and is the reason for the groove in it but so far haven't tried that yet though I may soon.  It would be nice to be able to tune it so the brass lazily ejects out the side and lands beside of my feet.



Combined with the longer stroke rifle buffer, and heavy spring, makes this really nice to shoot and also helps tame some of the recoil better too (compared to a carbine tube).

Speaking of the spring, I did something that I've never known any company doing for PCC's.  I made it with a 1/4" guide rod so I could use wilson combat 1911 flat coil springs to the various weights they offered so I could better tune the action to the load I was shooting.



I personally like how flat coil springs work because they last longer and don't over compress when they're all the way back and they come in weights from 12 pounds all the way up to 24 pounds. 

Since I only shoot the hottest handloads out of that gun, I'm currently using the 24 pound spring in my gun and it feels really nice to shoot.  It still ejects the empty cases out into low earth orbit and they land in the next zip code, but they typically land in a nice tight circle.  She's a little kitten on the muzzle rise though.  It's certainly a nice lightweight brush gun for sure.

[The_Shadow]

Very interesting  John!
I have considered getting a heavier Buffer for my Bear Creek Arsenal 10mm.  They mentioned the buffer was 9 oz???
I'm considering the KVP 10oz Tungsten Blowback Buffer for mine.
However another person (Jeff) mentioned they went with a 11 oz buffer and a 308 carbine buffer heavy spring.  However, mention who he purchased that from.

Therefore I'm sort of still looking

[John A.]

I've used the kaw valley 10oz buffer and a 308 caliber flat coil spring.  They do work.  And realistically, if you're already running a 9 oz buffer, adding another ounce probably isn't going to make a world of difference either.   If it were me, I'd just buy one of the AR10 flat coil springs first and see if you're happy with it.  If it does nothing else, the flat coil springs will still remove the sproing and some of the noise while adding some pressure to the rear of the bolt. 

If you load really hot though, they still eject the brass rather "enthusiastically" (lol).

The 308/AR10 caliber flat coil springs are being sold by different companies at the moment.  Strike Industries and Wilson Combat are generally less expensive flat coil springs than the Tubbs/Superior shooting brand if you're trying to save a few dollars.  I believe the tubbs springs are still better though.  But only marginally.

Which is much of the reason that I made my latest buffer to accept common 1911 springs so I could switch them out and tune it to the loads that I'm shooting.  I believe the 20, 22 and 24 pound springs would be the most common for 10mm caliber.  Though, some of the powder puff stuff that intentionally tries to download it into 40S&W subsonic pressures, you may need an 18 pound spring for that probably.  But I don't personally know anyone that are running loads like that in their carbines though.  Nor why the would, other than to try to impress the ladies at the gun range at how quiet their gun is but that's probably a whole different conversation.   

[The_Shadow]

Thanks for the reply John!