A2 profile cut

[lazyengineer]

Related to the current PSA 20" BBL deal; they like using A2 cut profiles. I've never been a big fan of that cut.

For something like a 6.5 Grendel, is there any advantage to the A2 profile cut? It seems like a goofy spec, that had something to do with barrels getting bent from bayonet torquing or some-such; irrelevant to us. It adds weight, but seemingly in the wrong place. But that said; I wonder - is there any accuracy advantage to the extra weight out in the last 6" or so of BBL length like that? If you took an A2 cut barrel vs a light weight barrel that didn't have the extra mass out there, would the A2 shoot any better?

Also, my search-fu was not strong. What's the syntax for searching for something like "A2" and "barrel". When I type "A2 Barrel" in the search bar, it pulls up everything that has Barrel or A2, without necessarily having both.

[grayfox]

I'm not familiar with an "A2" cut, is this something like the "govt profile," with the thicker diameter from gas journal to muzzzle?
If so... then not all mfrs do that profile. PSA is probably doing that to save cost in making the bbl (buying lots of the same profile blanks), faxon has one similar (gunner profile). Barrel profile is a spec you want to check before plunking your $$ down.
here's the grendel custom search engine, maybe this will help you out.

https://cse.google.com/cse?cx=016368947416500061353:paqd_0xcu1o

[Klem]

Related to the current PSA 20" BBL deal; they like using A2 cut profiles. I've never been a big fan of that cut.

For something like a 6.5 Grendel, is there any advantage to the A2 profile cut? If you took an A2 cut barrel vs a light weight barrel that didn't have the extra mass out there, would the A2 shoot any better?
.

52' is an avid history buff when it comes to the M16/AR15 so he might have more detail.

My thoughts are that the heavier the gun the more stable it is when shooting supported. This is why there are weight limits in competition, like the 8kg rule for F-Class. Any weight down the end of a barrel, for example a heavy suppressor or in your case, a thicker barrel will help precision.

My understanding is that the A1 profile ('pencil' barrel) was replaced by the A2 profile because the thicker barrel dissipated heat better in sustained fire situations. And yes, they are less prone to damage. The thin section under the handguard was kept to continue compatibility with the M203 grenade launcher. So thick forward of the block and thin behind it. Sometimes you see a one inch thinner cut section on barrels in front of a shorter gas port, which is where the 40mm launcher clamps.

[VASCAR2]

I like the A-2 profile barrels but I felt like the A-2 profile was a compromise compared to the A-1. The A-2 profile is indeed heavier than the A-1 and was supposedly adopted in effort to appease the Marines who’s qualification required engaging targets at longer range targets. The A-2 also changed to the fully adjustable rear sight and slightly longer A-2 butt stock.

Here is a picture of one 6.5 Grendel A-2 profile SS barrel from PSA.

[ike838]

The A2 profile was an attempt by the Marines to accurize the original .625 " diameter A1/M16 pencil barrel by bumping it up to a .750 diameter. Turned out to be pretty heavy so they thinned it back down to .625 from the gas block aft and called it good. Only a committee could do that, lol. The M4 profile is a shortened A2 with a section turned down to .625 so legacy grenade launchers would still fit.
The Faxon Gunner that I have in .556 is a shooter and it has the beef in the back and skinny part forward like God intended.

[biodsl]

The Faxon Gunner that I have in .556 is a shooter and it has the beef in the back and skinny part forward like God intended.

Which is why I like BFT's profile on his group buy barrels so much. The A2 profile always struck me as strange.

[Kswhitetails]

I think a bit of the reason that folks make so many GOVT and A2 profile barrels is that the machine programs are a dime a dozen; Proven. And they sound official. I'm not sure there's any advantage of the A2 otherwise, it's just easy to mass produce since they've been through all the bugs and made them easy.

[LRRPF52]

They increased the fore end diameter with the M16A2 because there was an erroneous assumption that soldiers were opening ammo crates with M16A1s, and bending the barrels.

They concluded this by doing bore gauge tests on fleet rifles and the gauges would get caught right around the Front Sight Base.

In reality, it was just carbon fouling at the gas port which hung up the gauges, but nobody cared to notice that, so we got the A2 heavy fore end.

None of the barrels were actually bent.

Add it to the list of the many failures passed off as upgrades to the M16A2 over the M16A1, with the fire control mechanism being the biggest offender, followed by the Length of Pull increase to the stock.

Good features that came from it were:

* Brass deflector
* Increased strength materials for the furniture (Lots of Type A, B, C, D, and E M16/M16A1 stocks had cracks around the junction between the stock and the lower receiver, and would break during butt-stroking. Handguard tabs around the vent holes on the triangular guards would break.)
* 1-7 twist for M855

The rear windage adjustment and elevation were unnecessary for a combat rifle, and you will not find a single 0311 Marine who ever had his Squad Leader call out to the Squad to set their rear elevation drums to a particular range for engaging TGTs at distance, especially with all the M60E3s and M249s in the Squads and Platoons.

As to the barrel profile, there's an argument in favor of a heavy fore end for resisting barrel whip harmonics, but when you're shooting M855, it doesn't matter anyway and the accuracy requirements were somewhere around 4 MOA IIRC.

The M16A1s pencil barrel is far superior for a fighting rifle in my experience, and I was issued both in several Infantry units. My first unit still had M16A1s in 1994-1995, when we got brand new M16A2s. I used the M16A2 in Infantry OSUT, but really liked the M16A1s due to the noticeably reduced weight and the superior fire control group of S-S-A.

M16A1 wasn't bad for close quarters fighting either, and felt like a lightweight carbine.

[SDW]

I have no military experience, but I'll agree as much as I can with what LRRPF52 says about the A1 config. I have a Colt SP-1 lower that has a surplus A1 upper atop it. (I bought this setup from my brother, who'd owned it for years.) I didn't care a all for the triangular HG so I swapped to the newer A2 type; huge improvement IMO.

But anyway, on to my point. The A1 20" upper makes for about as "handy" and well balanced a rifle as I've ever held. Feels like half the weight of any of my various other uppers, though I know it's only slightly lighter in weight than the next heaviest. There's just something about it. And my brother said it would shoot down to about 1 MOA for him with his 55 gr hand loads, if he squeezed of his shots slowly and carefully.

[FLshooter]

I just got a Criterion 22” Hbar barrel in 6.5 Grendel.It’s .920 till it gets to the .750 gas block.Then it slims down to .680 or so,an inch before the threaded muzzle.Sorta like the psa barrel.
No,I do not like that style either. Wish they left it .750 all the way.But I can tell you this,the 22” Criterion hbar barrel is one hell of a upgrade from the BCA junk 24” barrel I had.

[SDW]

^^^ frustrated that I can't see a larger version of your avatar. LOL

That barrel does sound like a great shooter. But I'll be it's a heavy setup. My only Grendel barrel so far is Ballistic Advantage 20" in their "DMR" profle, It's probably a bit like you were saying you'd like.

[FLshooter]

^^^ frustrated that I can't see a larger version of your avatar. LOL

That barrel does sound like a great shooter. But I'll be it's a heavy setup. My only Grendel barrel so far is Ballistic Advantage 20" in their "DMR" profle, It's probably a bit like you were saying you'd like.

0467C625-6323-4BFE-A0D1-99FCA6384D6E.jpeg

[SDW]

Thanks. Very nice.