Which AR-10?

[brutal]

Let me know what you find. I was in a discussion about this yesterday afternoon. I was told by a very good authority that the 25s would fit and the 20s wouldn't, but this only applied specifically to M118LR spec ammo.

Tripped across this thread again so I checked. The M118LR I have here, headstamp 09, just fits the LR20 PMAG. Just. Barely.

[brutal]

Sounds like your bolt catches are made very poorly. I like a lot of Aero's stuff, but after 2 have broken, I wouldn't be putting any more in.

I've never had a bolt catch break using the appropriate rifle buffer in a .308 A2 configuration.

Are you saying you put a carbine style buffer in your rifle with the A2 tube still?

Looks like this?



If so, that is a bad idea. The shorter buffer will allow the larger diameter of the body of the bolt carrier to impact the threaded portion of the lower receiver, which can cause damage to the threads, and eventually can cause the lower receiver to crack at the base of the buffer tube hole.

I bought a DPMS from a guy that had put a carbine buffer in an A2 rifle buffer tube, and the carrier had dug into the buffer tube threads about a 1/4 of an inch.

It's your gun, do as you wish, but understand that they are designed with that buffer for the rifle A2 tube for a reason.

My first Sig 716P carrier made contact with the lower receiver and took some pretty good chunks out of it. Issue arose once I started shooting it suppressed.

They replaced the complete rifle.

Sig redesigned the platform and now uses uses a flat sprint, H2 buffer, redesigned BCG and bolt (2 ejectors), and has cutouts in the lower. However, I've pressed the BCG all the way back and the bearing surface is not really even close to the lower now.

[belizejet]

Even if they are the same weight? You are talking about the threaded portion where the buffer tube screws in, correct? One was Aero and one was DPMS. What do you suggest for a bolt catch? Are you sure the guy didn't use an AR-15 spring also? The only thing different in my set up is the length of the buffer. I guess I don't get it because no matter what buffer you use the bolt carrier is going back into the buffer tube. The buffers are the same diameter. I'm sure the lip on the .308 buffer serves a purpose but I'm not sure what for. I'll do some more research. Maybe because all my rounds are suppressed? It was very hard to charge before I switched the buffer out. It almost took two hands. I'm
Pretty sure it was because the spring was already compressed a bit in the bolt forward position and thus had maximum forward spring on the cycle to smash forward toward the bolt catch. Thanks for the heads up and I'll look at it. I got the idea from a guy who has been doing it in a .308 AR for a while. Maybe it's the 7.5 Creedmore vs .308?

[brutal]

However, I've pressed the BCG all the way back and the bearing surface is not really even close to the lower now.

Even if they are the same weight? You are talking about the threaded portion where the buffer tube screws in, correct? One was Aero and one was DPMS. What do you suggest for a bolt catch? Are you sure the guy didn't use an AR-15 spring also? The only thing different in my set up is the length of the buffer. I guess I don't get it because no matter what buffer you use the bolt carrier is going back into the buffer tube. The buffers are the same diameter. I'm sure the lip on the .308 buffer serves a purpose but I'm not sure what for. I'll do some more research. Maybe because all my rounds are suppressed? It was very hard to charge before I switched the buffer out. It almost took two hands. I'm
Pretty sure it was because the spring was already compressed a bit in the bolt forward position and thus had maximum forward spring on the cycle to smash forward toward the bolt catch. Thanks for the heads up and I'll look at it. I got the idea from a guy who has been doing it in a .308 AR for a while. Maybe it's the 7.5 Creedmore vs .308?

I'm guessing your question was addressed to Grant H.

However, I will suggest that you check how far your BCG will go into the buffer tube with the spring/buffer you have installed. If you're using a carbine tube, you would have a carbine spring and bufffer - although tuned for your rifle. An A2 rifle length tube should have a rifle spring/buffer tuned for your rifle.

BCG's only go in about half way. The front half of the BCG on a .308 is larger in diameter than the rear (that fits a standard AR-15 buffer tube) and as Grant H. said, it will contact your lower if not "bottoming out" on the buffer/spring combo. If that bearing surface contacts the lower, you're gonna break shit.

Here's a pic of my damaged Sig lower before it was replaced.

[belizejet]

I get it now. Much better explanation. I wish I had another AR-10 in 6.5 Creedmore to compare it too. I feel like I started from scratch in building my first AR-10 in 6.5.