meee- The NFA world has some tricky things about it but for the most part it is fairly straight forward.
- As far as 10.5" barrels, no the ATF doesn't care how short it is, just as long as it is properly registered. Some local laws may exist that say otherwise but I've never heard of any though it's always best to research and find out.
- The current ACR barrels (mid length gas system) can go down to about 12" and still function, w/ gas port work. The 10.5" barrels use a "carbine length gas system" which is shorter. We'll have to wait for those barrels to come out that have the necessary parts modified for such a short barrel.
- Yes, if YOU make the SBR then it has to be stamped/engraved with your info; name, city and state because now you are the actual maker of the rifle. You can mark the the receiver, or, every barrel that meets the NFA rule which is <16". Alternatively, you can order factory direct an SBR through your local Class3 guy and it will have only the factory markings on it. It's unclear if BM will do this or not so time will tell. I'm under the impression they sell SBR'd AR's so why they wouldn't do that with the ACR as well is beyond me.
- The criteria for approving an SBR is a clean bill of health, so to speak, in terms of the basic background check they conduct. Not a convicted felon, not on a watch list, etc, etc. If done as an individual the FBI runs your prints too.
- There are ACR's for ban states and they are modified with specific features but everything is reversible yet so if you bought one in CA you could have a ceremony of dumping the stupid parts on the state line when you move I 'spose. In a proper waste receptacle of course. No littering! ;D
[quote author=Mr_Gixxer link=topic=164.msg862#msg862 date=1284861571]
Where can I get a 10.5 inch barrel?
I know a class 3 dealer local. Could a 16 be cut down and have paperwork filed on it?
Would a 1:7 be better for a shorter barrel?
Do they have a 1:7 available yet?
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I won't get into the debate of barrel twists. I say get what you want and be happy with it. Just a couple things to think about however 1) That tin can, box, IPSC target or whatever you are shooting at doesn't know what twist you're using, and 2) neither does the bullet.
Take a look at what you shoot or plan to shoot and base your decision off of that. If you plan on only shooting Mk262 or 75gr TAP rounds then maybe a 1:7 would be best. If you don't then maybe the 1:9 would work. (Oh, several folks have been posting very good accuracy with the 77's and a 1:9 ACR. Just FYI...) I've got a few SBR barrels for my XCR and to be honest I couldn't tell you which one is 1:7, 1:9 or 1:8 unless I really took a look at them. They all shoot fine.