View Full Version : Stupid Question: 12.5" + 4" linear comp?
Hi all,
I've been here for years... I'm fooling with the idea of building a non-NFA upper with a 12.5" barrel and a Kaw Valley Precision "XL" linear comp, which is 4.125". Nevermind the NFA issues: I would make sure that it's a full 16" and have it pinned and welded.
My question is whether this is a fool's errand. This seems appealing because I like the idea of a suppressed SBR, but I live in California and it's impossible. (Trolls: Spare me the anti-California rants.)
So, I can get a linear comp, and KVP's new "XL" is huge and should at least direct much of the blast/flash away from me, in the SHTF event that I need to fire the gun indoors.
Alternatively, I could do a 14.5" barrel with a regular linear comp pinned and welded, but it seems like the bigger linear comp would do better directing blast forward, and the 2" of barrel length doesn't seem like enough to matter in terms of muzzle velocity (maybe 150fps?).
Please advise...
Leaveammoforme
11-16-16, 22:00
Your "barrel" is going to be 16 inches regardless. Might as well get the velocity.
I guess that's the crux of my question: Assuming the bigger linear comp works, would it be worth giving up 150fps or so to reduce blast?
I'm guessing that it's worth it at down-the-hallway or even across-the-yard distances, but I'm only guessing...
I guess I would ask myself, what is the benefit of this setup over a standard 16" barrel.
I personally couldn't think of any, yet I could come up with a few negatives. You may have a different perspective that not seeing however.
I guess I would ask myself, what is the benefit of this setup over a standard 16" barrel?
The benefit would be to reduce blast, or at least direct as much of it as possible away from me...
A 16" barrel is a non-starter for me. Given that I would have some kind of muzzle device, I'd rather have it pinned and welded to reach 16", rather than 16" plus a device for 17"+. I have two 14.5" ARs with pinned & welded devices...
Leaveammoforme
11-16-16, 22:08
I don't think you'd get anymore blast reduction from a linear comp than you would the extra barrel length. The powder will be burning in the open air versus behind a projectile for those 2 inches.
Never compared the two side by side but I'd imagine the blast would be extremely similar.
I don't think you'd get anymore blast reduction from a linear comp than you would the extra barrel length.
I'm not an engineer, but as I understand it the linear comp works like a muffler on a car, and it'll make a big difference in the level of blast, at least for the shooter... AFAIK the Noveske "pig" works well, and this is just a bigger version.
I'm thinking here of the photos I've seen comparing the "flash hiding" performance of various muzzle devices vs. bare barrels.
I don't think you're gaining anything with a pinned 12.5" & I'm not sure you'd notice much of a difference in the "blast" between the two pinned setups. (12.5 vs 14.5) If anything, the 12.5" may still be worse even with the MD.
I think 14.5's are some pretty nice shooters but you've got that covered.
Save the money & spend it on something more worthwhile.
Just my opinion...
Leaveammoforme
11-16-16, 22:20
I'm not an engineer, but as I understand it the linear comp works like a muffler on a car, and it'll make a big difference in the level of blast, at least for the shooter... AFAIK the Noveske "pig" works well, and this is just a bigger version.
I'm thinking here of the photos I've seen comparing the "flash hiding" performance of various muzzle devices vs. bare barrels.
Understood. But, you're still going to have a linear comp on the 14.5 not a bare muzzle. Albeit, just shorter.
If the linear comp worked like a car muffler, it would be a suppressor. It directs the blast forward but does not reduce the noise. In your case, I would go with a longer barrel and a shorter linear comp. If I were in Cali, I'd go with a14.5" barrel and a pinned Battlecomp 2.0
Why not go 13.7" with a Noveske KX-3 or 5?
Mr. Goodtimes
11-16-16, 22:34
This idea makes no sense to me. You're talking maybe 1.5 in of overall difference yet you give up velocity over a 16. This setup literally has no advantage over a 16in barrel and has s couple pretty big disadvantages.
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SomeOtherGuy
11-16-16, 22:36
I guess that's the crux of my question: Assuming the bigger linear comp works, would it be worth giving up 150fps or so to reduce blast?
No.
FYI:
"Machined from billet 6061 AL, the KVP XL Linear comp is an excellent light weight, highly functional compensator for your pistol caliber builds!"
I'm not sure how a pin and weld job works with an aluminum muzzle device. I suppose you can still pin it - but weld it? ATF has some rather detailed requirements about welding or high temp silver solder and I'm not sure you can do either one without damaging the aluminum "comp."
Also, I have a suspicious feeling that ATF is going to look into this 4" long "linear compensator" and probably frown on it. Remember how ATF forced a recall of dummy suppressors that had no baffles, but were a long open tube with a small hole at the end? This looks similar.
I'm optimistic that we might get the "Hearing Protection Act" passed in 2017, and if we do I'm buying an assortment of legal no-stamp suppressors. Until then I wouldn't roll the dice on this "XL" "comp".
mkmckinley
11-16-16, 22:39
Seems like a dumb idea but try it out and let us know how it works.
No.
FYI:
"Machined from billet 6061 AL, the KVP XL Linear comp is an excellent light weight, highly functional compensator for your pistol caliber builds!"
I'm not sure how a pin and weld job works with an aluminum muzzle device. I suppose you can still pin it - but weld it? ATF has some rather detailed requirements about welding or high temp silver solder and I'm not sure you can do either one without damaging the aluminum "comp."
Also, I have a suspicious feeling that ATF is going to look into this 4" long "linear compensator" and probably frown on it. Remember how ATF forced a recall of dummy suppressors that had no baffles, but were a long open tube with a small hole at the end? This looks similar.
I'm optimistic that we might get the "Hearing Protection Act" passed in 2017, and if we do I'm buying an assortment of legal no-stamp suppressors. Until then I wouldn't roll the dice on this "XL" "comp".
If the BATF had a problem with the extra long compensater, they would have sqwaked about it
SomeOtherGuy
11-17-16, 06:58
If the BATF had a problem with the extra long compensater, they would have sqwaked about it
They don't always say things up front. For starters, you don't have to get a ruling from them before offering a new muzzle device, so they may be learning about it the first on JoeBob's mailing list. Even if the maker did get a ruling from the Firearms Technology Branch, sometimes they change their mind later.
Also, even if ATF is fine with the comp, how do you permanently attach an aluminum comp to make a legal 16" non-NFA barrel?
"Machined from billet 6061 AL, the KVP XL Linear comp is an excellent light weight, highly functional compensator for your pistol caliber builds!"
Am I the only one who noticed the aluminum version is for pistol calibers? The rifle version is steel and only 2 1/8" long.
SomeOtherGuy
11-17-16, 07:15
I hadn't noticed the XL was only for pistol calibers until you said so. Looks like the description says it's for pistol calibers, but the threadings offered are compatible with typical rifle barrel threads, see below. I suspect this is a case of "we don't recommend you do ___, but we aren't stopping you from doing ___."
The dedicated rifle version of steel has been around for a while (1-2 years?) and doesn't raise the same issues either on permanent attachment or ATF-deemed legality. It also wouldn't work for OP's goal of a 12.5" barrel made legal at 16+" through the device.
We designed the KVP XL Linear Comp for pistol caliber carbine, and pistol builds. The extra long length of this comp makes it an extremely functional linear comp, by utilizing a HUGE expansion chamber. In addition to the blast controlling functionality, it allows builders the option to use longer Hand Guards in short barreled pistol caliber rifle and pistol builds. Machined from billet 6061 AL, the KVP XL Linear comp is an excellent light weight, highly functional compensator for your pistol caliber builds!
NO CRUSH WASHER NEEDED FOR INSTALLATION (Install with crush washer or other timing device if indexing of wrench flats is desired)
Thread Types: 1/2x28 TPI, 5/8x24 TPI, 1/2x36 TPI, .578x28 TPI
Overall Length: 4.125 Inches
OD: 1.4 Inches
Caliber: Pistol Calibers .45 ACP and Smaller
MOLON AABE
11-17-16, 07:21
With a 5.56 rifle the absolute last thing you want threaded to you're muzzle is anything constructed entirely of aluminum.
A 12.5" barrel with any length muzzle device short of a suppressor is going to have more muzzle blast, flash, and noise than a bare (no muzzle device attached) 14.5-16.1" barrel. Save your money for something that will actually be useful such as a good quality optic, more mags, ammo, ink pens to write your congressperson....jk but seriously aside from cool factor points I cant come up with a single advantage of 12.5" barreled + 4" muzzle device.
Velocitas, Opprimere,
Violentia Operandi
They don't always say things up front. For starters, you don't have to get a ruling from them before offering a new muzzle device, so they may be learning about it the first on JoeBob's mailing list. Even if the maker did get a ruling from the Firearms Technology Branch, sometimes they change their mind later.
Also, even if ATF is fine with the comp, how do you permanently attach an aluminum comp to make a legal 16" non-NFA barrel?
Not commenting on the aluminum part, just the length. When the BATF had a problem with certain muzzle devices, it wasn't because they were long, it was because the devices reduced the sound signature more than was allowed (which I believe is 2db)
crusader377
11-17-16, 13:01
Hi all,
I've been here for years... I'm fooling with the idea of building a non-NFA upper with a 12.5" barrel and a Kaw Valley Precision "XL" linear comp, which is 4.125". Nevermind the NFA issues: I would make sure that it's a full 16" and have it pinned and welded.
My question is whether this is a fool's errand. This seems appealing because I like the idea of a suppressed SBR, but I live in California and it's impossible. (Trolls: Spare me the anti-California rants.)
So, I can get a linear comp, and KVP's new "XL" is huge and should at least direct much of the blast/flash away from me, in the SHTF event that I need to fire the gun indoors.
Alternatively, I could do a 14.5" barrel with a regular linear comp pinned and welded, but it seems like the bigger linear comp would do better directing blast forward, and the 2" of barrel length doesn't seem like enough to matter in terms of muzzle velocity (maybe 150fps?).
Please advise...
I personally think you are overthinking this. I personally would just get a good 16" barrel carbine or middy and call it a day. The chances of you engaged in an indoor SHTF event is minimal and even if you were, a semi auto AR is not a particularly high flash weapon anyway and I just think you are spending a lot of extra money and losing velocity and flexibility for a non-issue concern of directing muzzle flash forward.
I hadn't noticed the XL was only for pistol calibers until you said so...
Aha... I had noticed that it was advertised for pistol calibers, but I thought that was simply pointing out that the exit hole would be big enough to clear 9mm.
I hadn't realized that it's made out of aluminum. You guys are right that that's a deal-breaker.
FWIW, I have a KVP linear comp (the little steel one) on a 17HMR, and it's a nice piece. It's hard to know how much it's reducing the (already minimal) muzzle blast for me, because I didn't do back-to-back comparisons with/without. I have it in case I get a shot at a crow without ear protection...
I hadn't noticed the XL was only for pistol calibers until you said so. Looks like the description says it's for pistol calibers, but the threadings offered are compatible with typical rifle barrel threads, see below. I suspect this is a case of "we don't recommend you do ___, but we aren't stopping you from doing ___."
Thread Types: 1/2x28 TPI, 5/8x24 TPI, 1/2x36 TPI, .578x28 TPI
While these may also be rifle barrel thread patterns 1/2x28 and 1/2x36 are also 9mm thread patterns and 5/8x24 and .578x28 are also common 45 acp thread patterns.
I wouldn't recommend a MD designed for a pistol caliber be used on a 556 rifle.
I think I would want to know what the difference in blast between a 16" barrel and the 12.5" with linear doohickey would be. It might be that difference might not be huge. Maybe the 16" might be less blast or only slightly more. If that is the case then I would stick with the 16".
Bimmer, have you shot a 16 inch gun indoors? Outside of the noise, which is going to be horrendous either way, its not that bad.
I spent 3 hours today in a shoot house training CQB active shooter type stuff. Everyone was running our patrol rifles which are Colt 6920s. I had multiple instances being in a 15x10 foot room shooting targets with two other guys right next to me doing the same. Yeah you can feel the blast but it isnt disorienting at all and in the moment, when I was thinking more about clearing the rooms, I really didn't even notice it.
I think I would want to know what the difference in blast between a 16" barrel and the 12.5" with linear doohickey would be...
Yes, basically, this was my question, and not having the two to compare, I was hoping for some insight...
Bimmer, have you shot a 16 inch gun indoors?
No, I'm basically a middle-aged mall ninja... However, I've been to indoor ranges where people were shooting centerfire rifles, and the concussion was impressive.
Rayrevolver
11-18-16, 11:53
Good catch on the "pistol" comp. Reminds me of a company that sold the "Disintegrator" comp a few years ago that disintegrated during T&E... oops.
Don't forget that some barrels are longer than advertised. Some folks get 14.5" barrels that measure 15", so the pinned muzzle devices options to get to 16" are plentiful. Maybe try and find a ~15" and pin a normal device.
Some folks get 14.5" barrels that measure 15", so the pinned muzzle devices options to get to 16" are plentiful. Maybe try and find a ~15" and pin a normal device...
Well, I'm thinking of what to put on a BCM lower, so I'm looking at BCM uppers (almost exclusively), and the options there are 12.5, 14.5, or 16.0...
Linear comps are usually 2" or or so, so a 14.5" barrel is no problem.
Well, I'm thinking of what to put on a BCM lower, so I'm looking at BCM uppers (almost exclusively), and the options there are 12.5, 14.5, or 16.0...
Linear comps are usually 2" or or so, so a 14.5" barrel is no problem.
I had a 14.5" BCM BFH Middy, it was the best shooting gun I owned. It measured 14.8" so I pinned on a standard A2.
I had a 14.5" BCM BFH Middy... it measured 14.8" so I pinned on a standard A2.
I guess I could do this... Just order a 14.5" from BCM, and then measure it when it arrives. I'm surprised that their barrel came in 0.3" over advertised.
Since the 12.5" and 4" comp isn't a viable option, now I'll go back to the drawing board. (Don't worry, I'll be back with more stupid questions later.)
I guess I could do this... Just order a 14.5" from BCM, and then measure it when it arrives. I'm surprised that their barrel came in 0.3" over advertised.
Since the 12.5" and 4" comp isn't a viable option, now I'll go back to the drawing board. (Don't worry, I'll be back with more stupid questions later.)
Yeah, it seemed to be fairly common that they'd vary in size. There was a thread about it awhile back but I believe it was either locked or scrubbed all together.
I thought you already had some 14.5" barrels? If none are a mid-length, you need to get one.
TexasAggie2005
11-18-16, 14:26
I'm surprised that their barrel came in 0.3" over advertised.
I'd believe it. A good friend of mine bought a BCM 11.5" barrel, it came in longer and heavier than advertised. I want to say about .25" long and almost .75oz heavier.
fallenromeo
11-18-16, 15:19
Bimmer, if it is back to the drawing board, but you like the idea of a pinned and welded linear comp, take a look at a 13.7 with the KX5 or Hera Arms linear comp. Both should meet your needs and look cool enough.
Just out of curiosity, where in Humboldt are you? I was born and raise there until left for college.
"So, I can get a linear comp, and KVP's new "XL" is huge and should at least direct much of the blast/flash away from me, in the SHTF event that I need to fire the gun indoors"
Could someone please explain to me how any muzzle device short of a suppressor can reduce noise/pressure pulse more than a bare muzzle?? It's not like the blast can make a U turn and come back to bite you. I promise you if you touch off a rifle in your bedroom it ain't gonna matter if you have a linear comp or a 3Gun brake on it.
The only benefit of a 12.5" is short length, either suppressed or not. A long ass muzzle device is pointless. Might as well get some extra velocity and powder burn (and thus reduced blast). So either a 14.5 + pinned and welded, or a 16" with swappable muzzle device.
Jwknutson17
11-18-16, 20:57
Might as well go for the 16. I can promise you, if you squeeze one off indoors, it's not fun and your ears will hate you for a week, and it doesn't matter what MD you have on. Even with a can and no ears, still insane loud. Skip the whole 12.5 pinned to 16 and just go with the 16.
Fwiw, a 12.5" barrel and a socom mini will be under 17" total barrel length, and actually quiet the shot.
Jwknutson17
11-19-16, 08:53
Fwiw, a 12.5" barrel and a socom mini will be under 17" total barrel length, and actually quiet the shot.
This is what I would do if you want a double stamp gun. And is an awesome setup. Can't get much of a better do all then a 12.5 with a SOCOM Mini.
California does not allow the possession of any NFA items
Press Check
11-23-16, 00:21
If you own a pistol lower, you can legally possess NFA uppers in California.
Then it's a pistol upper, not an NFA upper. NFA items require a tax stamp
Press Check
11-23-16, 00:26
Semantics....
There is no such thing as an NFA upper. It's wording that is added for non critical thinkers.
Semantics....
Semantics....
Semantics or not, California forbids the possession of any NFA item. That means no destructive devices, machine guns, silencers, short barreled rifles, short barreled shotguns (or anything else that requires an NFA tax stamp to legally possess) are legal in the state of California.
Rifled barrels that are shorter than 16" or AR uppers with barrels shorter than 16" do not require an NFA tax stamp, therefore they are not an NFA item
... because words mean things.
You guys have totally run off the tracks...
NFA isn't an option in California, period. If I get a barrel of less than 16", then I would have a muzzle device pinned/welded. My 14.5" barrels are pinned/welded to 16"+.
An AR pistol is a non-starter (for me at least), because California's gun laws are even more stupid/frustrating regarding handguns than ARs, and it would mean even more jumping through hoops and bastardizing of a gun to make/keep it legal.
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