Buffer tube size for Alexander Arms Grendel lower?

[Rawdeal]

A few months ago, I purchased an "R-TACTLOWR" complete lower from Alexander Arms, and last week I went to upgrade the stock and discovered AA had used a commercial spec buffer tube.

Is there a reason (other than AA profit margins) that a commercial spec tube would be used in, what I would presume to be, a higher end lower (e.g. is there something about the Grendel that makes commercial spec better?)

[pinzgauer]

From memory commercial was "the" standard early on as it's what Colt supplied on their commercial rifles which was all that was available to civvies.

Since then things have changed, and mil-spec (in all things AR) is becoming the norm. Just about every civvy mfg used commercial tubes, it was what was available. So I don't think AA cheaped out. Retail cost was roughly the same for years, though with the focus on mil-spec you see the commercial price dropping now.

Commercial is slightly less expensive to mfg from a machining perspective, which presumably was why colt went with it on the CAR-15 for the civvy market. You really did not hear about mil-spec vs commercial buffer tubes until the M4 was wide use, and specifically when the aftermarket (Magpul, LMT, VLTOR) started making stocks for M4. So I don't know if it was part of the M4 spec or went back to the early XM-177. Have to do some research there.

The difference is mostly how the threads are made. The threads are the same size, but commercial is cut into the tube, and the thus the metal is thinner there. Mil-spec threads are rolled and has full stock thickness even under the threads, so it's nominally stronger in case you need to use your M4 as a bat because the barrel melted.

Conventional wisdom has that the mil-spec stock is also forged, which it should be. But there are many sold as mil-spec which are not. You'll have to do a bit of research to see what alloy is used. LMT & DD both meet the FN/Colt TDP for the buffer tube (really receiver extension) in terms of material & mfg. Many "mil-spec" use the similar alloy extrusions as the commercial stocks, just roll the threads instead of cut them.

I'm currently using only mil-spec tubes (forged) on my builds as it really does not cost any more to do so and you'll have the most flexibility in stock choices. But for years the norm was commercial tubes from nearly every mfg, so people would have been pissed if you had one that was different. The reality is that commercial tubes appear to hold up, given the zillions of m4geries out there you don't hear much about broken buffer tubes. (I'm sure it's happened somewhere though).

It's like the heavier barrels vs the Pencil.... yes, you can bend a pencil barrel if you use it to open a crate (apparently was a problem). And it was not as accurate in match shooting before the days of free float tubes. But for most usage the added weight of the heavier barrels was not justified for a carbine. So now you see some folks seeking out the pencil barrels to get back to the original weight/balance. The A2 weighed almost 2 lbs more than the A1 largely due to the heavier barrel!

Plus it's a bit silly to have the heavy barrel, then cut it for the M203. I like AA's carbine barrel, M4 profile, but with no 203 cuts. But if I build another carbine I may put a pencil barrel on it.

To me the only semi legit usage for the heavy barrel on carbines is supposedly it can handle sustained fire longer, though there are debates on that. And not an issue for civvy semi-auto use in carbines. From reading the original A2 heavy barrel came about from the markmanship team wanting one that can handle match shooting without free float tubes. Maybe some closer to that can comment.