Looking to complete a SBR project, the lower is already Form 1
I am having a hard time deciding between doing a 12.5 or 14.5 5.56
I have listed my pro’s and con’s below. the main thing that appeals to me about the 14.5 is the mid-length gas, but I also realize that the length is so close to my existing 16inch gun, I’m having a hard time justifying it.
What is important to me: Accuracy, smooth shooting gun, good platform for suppressor host, I already own 16 and 18inch 5.56’s with 1-6’s, plus 8inch 300blk. I want an 11inch rail, thus the 12.5 over 11.5 length, I find 10.5’s annoying to shoot, and want to get velocity, I would want to be able to shoot out to 400yd with this gun, maybe further, primarily run a RDS but could put 1-6 but mainly I will shoot it 100yd and in.
This gun will wear either the Silencer Omega or Specwar-K suppressor, just guessing 75% of the time. I will run an adj gas block and plan on tuning the gun for the can so its not over-gassed. I’m leaning towards just direct threading the omega to the gun with the 5.56 end cap unless I can feel a difference in recoil with the omega brake.
12.5
Pros
Shorter and handier
improved balance with suppressor
cons
carbine gas
harsher recoil
increased muzzle blast
14.5
pros
longer rail
mid-length gas
should be smoother, softer shooting
greater velocity
cons
longer
front heavy feel with suppressor
so close in length to current 16 inch gun
A properly sized gas port or a properly installed adjustable gas block will yield no differences between 14.5 mid or 12.5 carbine, as far as felt recoil is concerned in my experience. It’s not worth the $200 to build a 14.5 SBR. I’d personally opt for the 12.5.
Going to agree with the others here. The longest I would personally go if I was going to SBR an AR would be 12.5. The only reason I could see going to a 14.5 AR would be if you are wanting to clone the M4 you carried overseas and wanted it for sentimental value, otherwise 14.5 pinned and welded, or just 16 inch barrel makes more sense otherwise over the tax stamp.
I have a 12.5" that is absolutely amazing, and it wears a Saker-K 100% of the time. By far my favorite gun. DD CHF 12.5" barrel, Colt upper/BCG, Noveske 11" NSR hand guard.
I wouldn’t bother with a 14.5" SBR. I don’t think it’s worth the money. My initial reaction when reading your post was to recommend 11.5" but you specifically stated you don’t want that and why. Therefore I’m with everyone else here and feel the 12.5" is the best way to go. As far as a 12.5" with carbine gas system vs. a 14.5" with mid-length gas system goes, this is a non-issue. What’s important is that you have the proper size gas port for the barrel length and gas system combination. This is even more of a non-issue since you’re going to be running an adjustable gas block (as Leonidas24 talks about above).
I feel that the 12.5 5.56 AR is the best all around system. I like 14.5 barrels but to choose I will go 12.5 any day. 12.5 is the shortest barrel that you can go and still get proper stabilizing of the heavy 5.56 rounds. I have had no issues with a 12.5 out to 400 plus meters with MK262.
Different barrel lengths with the different gas lengths all have different attributes. There can be many more choices at hand than what the OP selected as far as selections for either. You can make a carbine gas 12.5" that never sees a can run well up to a mid gas suppressor only combo. The same goes for the 14.5" barrel, from carbine length to intermediate depending on how it’s used. Remember that regular carbine length, carbine + 1", mid gas, KAC length, intermediate lengths can be used in them, barrel length permitting. Dedicated porting is a personal preference over adjustable gas blocks. A rifle like (A5H2) action system increases reliability, as other things. Another thing to consider is how the silencer effects function, as far as cyclic rate changes through the gas tube, and blowback through the barrel. Each is independent and changes with every combo.
Just my 2 cents for this.
My recommendation for the OP would be the 12.5" gun. I don’t see much of a point in SBR’ing a lower for a 14.5" gun. If you want to build a 14.5" after you have your lower registered, then rock on. But for the first SBR, my vote goes with a 12.5" barrel.
I currently run the following set:
[ul]
[li]12.5" Centurion Arms CHF barrel (standard gas block)
[/li][li]Surefire MB556 brake
[/li][li]KAC URX4 10.75" rail
[/li][li]VLTOR A5 buffer system (A5H4 buffer+BCM rifle spring)
[/li][/ul]
This is, by far, the smoothest shooting rifle I own. Recoil is very mild (.22LR-like) and the muzzle stays very flat during rapid fire. I have run this gun with a Mk262 clone load out to 400 yards and have made hits on 12" plates pretty easily with a 1-7x optic (also got one lucky first-round hit on a 6" plate at the same distance). Have run it on a full-auto lower for a some mag dumps and have run it in a couple of 2-gun matches and 3 carbine courses. It’s also one of the most accurate guns I own. I benched it after about 3500 rounds (not so gentle firing schedule) and it will still print just above 0.75 MOA with match ammo.
The gas port in my barrel was a little smaller than I expected (.065" when new) but it has cycled both 5.56 and .223 pressure ammo with this setup. If MN legislature changes the suppressor laws this year, I’ll run either a Saker or SpecWar 556 K can on this gun pretty often. If the additional pressure becomes an issue for me, I’m conisder one of the Baby Govnah gas blocks from Micro MOA that allows you to drill your own gas port size in the gas block.
If both of them isn’t an option, go with the 12.5. The extra rail space is a non-issue for me, because I don’t reach out that far anyway. Use a quality barrel, and the 2" won’t make a difference out to 400 yards. This is pretty close to NickB’s setup, with 2 more inches of barrel and a FH on the Saker K.
I haven’t had any issues stabilizing 77gr Mk262 out of 10.3"-10.5" guns with a 1:7 twist rate, and I’ve seen even heavier rounds fired with good results.
Yep, you can get a direct thread and a flat front cap to make it even shorter/lighter. I really like the Omega since it’s so damn light, but the Specwar-K is more durable for lots of full auto fire or super high round counts. Everything has a 100% lifetime warranty, though, so you won’t go wrong either way.
