AR Rifle 20"

[OlongJohnson]

Trying to make sure I know what someone should know about A1/A2 receiver extensions / buffer tubes for rifles.

I've seen comments elsewhere that mil-spec for rifle receiver extensions is 7075 with rolled threads.

Obviously, 7075 is going to be stronger (~2x) than 6061, so I'd rule out 6061.

Not everyone understands this, but I'm enough of a fastener geek to know that rolled threads versus cut threads is actually a yuuuge deal. If TDP specifies rolled threads, then presumably a Colt tube has them. And the aftermarket being what it is, it's extremely unlikely any other manufacturer is bothering. Which would mean no other part really comes close.

It's been years since I looked at @rob_s' list; I don't remember it dealing with rifle stuff, but I was focused on carbines at the time.

TLDR: If I want the best rifle-style receiver extension, I just buy a Colt tube and roll on, right?

[JRB]

Trying to make sure I know what someone should know about A1/A2 receiver extensions / buffer tubes for rifles.

I've seen comments elsewhere that mil-spec for rifle receiver extensions is 7075 with rolled threads.

Obviously, 7075 is going to be stronger (~2x) than 6061, so I'd rule out 6061.

Not everyone understands this, but I'm enough of a fastener geek to know that rolled threads versus cut threads is actually a yuuuge deal. If TDP specifies rolled threads, then presumably a Colt tube has them. And the aftermarket being what it is, it's extremely unlikely any other manufacturer is bothering. Which would mean no other part really comes close.

It's been years since I looked at @rob_s' list; I don't remember it dealing with rifle stuff, but I was focused on carbines at the time.

TLDR: If I want the best rifle-style receiver extension, I just buy a Colt tube and roll on, right?

After going through the same dilemma, and being disappointed in discovering that the Colt A2 stock kit comes with a commercial buttplate and therefor deviates from the TDP, I opted for an AR-Stoner 'extreme duty' 7075 T6 receiver extension.
I found USGI A2 stock and A2 buttplate for sale on fleabay to round out the ensemble.
I was looking to duplicate a 'rack grade' M16A2 with that build, so the worn A2 stock and buttplate were exactly what I wanted.

But I did not scrutinize the threads on the AR-Stoner to see if they were rolled or cut, I simply wanted to avoid 6061.

Brownell's also offers a 7075 rifle length extension for a surprisingly cheap price ($27) but no word on the threads there, either.

[OlongJohnson]

I have the Colt and Brownells parts in my cart. May just order the Brownells extension and return it if the threads are cut.

[Bigghoss]

Trying to make sure I know what someone should know about A1/A2 receiver extensions / buffer tubes for rifles.

I've seen comments elsewhere that mil-spec for rifle receiver extensions is 7075 with rolled threads.

Obviously, 7075 is going to be stronger (~2x) than 6061, so I'd rule out 6061.

Not everyone understands this, but I'm enough of a fastener geek to know that rolled threads versus cut threads is actually a yuuuge deal. If TDP specifies rolled threads, then presumably a Colt tube has them. And the aftermarket being what it is, it's extremely unlikely any other manufacturer is bothering. Which would mean no other part really comes close.

It's been years since I looked at @rob_s' list; I don't remember it dealing with rifle stuff, but I was focused on carbines at the time.

TLDR: If I want the best rifle-style receiver extension, I just buy a Colt tube and roll on, right?

I wish I had heard this before I put together my fixed-stock middy, I've never even heard of rolled threads. I guess it's not a big deal to swap it out once a proper one is found. Does anyone know what Fulton Armory uses for their rifle receiver extensions?

[HeavyDuty]

Oh, God - receiver extension thread cork sniffing...

(Ducks)

[OlongJohnson]

No, this is about screwing to win.

[OlongJohnson]

It's been years since I looked at rob_s' list; I don't remember it dealing with rifle stuff, but I was focused on carbines at the time.

Waiting for lunch to heat up, I dug through my desktop machine and found all the "chart" info I saved back in the day. (I was late to the game and only have the discussion of criteria post-2012, plus a screencap I found somewhere of an uknown version of what I assume was the actual chart.) It is only M4 specific, so no breakdown of rifle vs. carbine. For buffer tubes, it discusses only diameter. Nothing about materials or manufacturing processes.

[Old Man Winter]

Deleted

[awp_101]

I keep coming back to look at this. I can't think of a single practical reason to build an 18" or 20" when my 16" is perfectly fine for any reasonable need I may have but dang if this one doesn't have the hamsters in my brain running in overdrive.

And now I remember I have a side charging upper receiver I'd put back for a project that never happened and I've been meaning to strip the Poverty Pony lower on my "good" carbine and put the parts in the spare Aero stripped lower so my "good" carbine becomes a "better" carbine. Sonofabitch this is about to get real...

[RONK]

Thanks!Any suggestion about buying/building an AR 20" DMR,stainless or chrome lined(SAM-R?),trigger,etc?Thanks again.