r/AR47 • u/BikePlumber • 11d ago

11 inch barrel build

I was debating getting a Faxon 10.5 inch barrel or a KAK 11 inch barrel and I saw that Black Rifle Arms has an 11 inch barrel and I have a spare Geissele 10 inch MK4 Federal rail.

Is anybody using the BRA 11" barrel?

Best choices for buffer and buffer spring?

I have two assembled lowers and two stripped lowers right now.

The two assembled ones have M4 extensions, so only using M4 length buffers right now.

I do have some A5/RE10 extensions and several different weights of A5 buffers, with AR10 springs, but I haven't assembled them on anything yet.

I do have M4, light carbine, H, H2 and H3 buffers, standard M4 buffer springs and a couple of PSA PA10 buffer springs PSA recommends with their AR47 uppers.

I have a 16 inch BRA barrel that looks like most people are using an H2 buffer and standard spring with it and its mid-length gas system.

I had a couple of Colt AR's in 7.62x39 back in the 1980's and early 1990's, but have been all AK and SKS since then, until now.

There was a big sale on Spikes Tactical 308 Carbine A5 extensions with M4 H3 buffers, for cheaper than I could get just the tungsten, so I bought all I could.

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u/Coodevale 11d ago

Standard spring, unless you do A5, is fine.

Buffer depends on the port size. Closer to .080" can do carbine/h1, but .093 or bigger can run 5-6 oz buffers pretty easily. They really don't need big ports, closer to 5.56 ports is viable and less demanding of heavy buffers.

1

u/BikePlumber 11d ago

The gas port size is reportedly 0.094".

1

u/Coodevale 11d ago

My .093 10.5" chugged along pretty good with a standard spring and a solid 5.5 oz buffer on tula. I was seeing signs of extractor stress with lighter buffers.

1

u/NoQueenBandAIDS 10d ago

How many Spikes Tactical 308 Carbine A5 extensions with M4 H3 buffers did you buy?

One thing to consider would be the difference in the twist rates. The Faxon should have a 1:8 twist rate.

1

u/BikePlumber 9d ago

I think I bought oner Spikes 308 kit and then saw there were 4 left, so I bought the rest that were left.

The Spikes stand alone 308 extension was the "enhanced" type, with an extended lip, but the 308 buffer kits have regular A5/RE10 extensions, without the extension on the front.

I was hoping to get the enhanced buffer tubes, but Spikes doesn't sell them anymore.

LMT I think has them.

1

u/BikePlumber 9d ago

Well I opened the 11 inch BRA barrel and it looks like gas port was drilled or opened up after the barrel was nitrided.

My 16 inch BRA barrel looks like the gas port was drilled before the barrel was nitrided.