View Full Version : SBRs and muzzle blast
wild_wild_wes
09-19-10, 17:55
What is muzzle blast like firing 5.56 through sub-14.5" barrels? I just discovered that AR pistols are a possibility in CA (SBRs are definitely not allowed); I was wondering how unpleasant they are to shoot. In the Vietnam era, the 10.5s had that long sound moderator attached, which made them practically 14.5s, but with the Mk18s this does not seem to be an issue. What are your impressions?
Muzzle blast? It's there, alright. Still lots of hot expanding gasses in play at so little distance from the chamber.
Just put a nifty little Cali-legal and very effective BattleComp on there!
muzzle device is the key, if you're concerned about blast from shorties. the muzzle device makes all the difference. you'll need to be careful about selecting one that's california legal, obviously. the problem with california-legal compensators is that compensators/brakes often tend to be the blastier devices.
check out the battle-comp... www.battlecomp.com.. it's cali legal, made in cali, and is an excellent comp, but brings flash and blast down to very similar to an A2 (which is not cali-legal, for stupid reason).
My 10.5" w/ AAC Blackout is no issue even indoors w/ the lights off (can see the flash, but it is very dim and not distracting)...don't know about the brakes. That battlecomp is probably your best bet, if it is about like an A2, that will help.
muzzle device is the key, if you're concerned about blast from shorties. the muzzle device makes all the difference. you'll need to be careful about selecting one that's california legal, obviously. the problem with california-legal compensators is that compensators/brakes often tend to be the blastier devices.
check out the battle-comp... www.battlecomp.com.. it's cali legal, made in cali, and is an excellent comp, but brings flash and blast down to very similar to an A2 (which is not cali-legal, for stupid reason).
Flash hiders are legal on pistols, you need a mag lock because the mag is outside of the grip. They are illegal on drop free mag rifles because they need to be "featureless".
The blast is more severe than a 16", but nothing to make one scared or distracted. Plenty of people shoot 10.5's and 11.5's. I do and love the shortened length. When on the line in a class, it may give pause to those next to you, but they soon realize it's no biggie. The benefits far, far outweigh the blast.
I fired my 11.5 with my muffs up on my head (above my hears on accident), and I thought the gun Kaboomed!!
I fired my 11.5 with my muffs up on my head (above my hears on accident), and I thought the gun Kaboomed!!
i left mines sittin on a table 30 feet behind me and let one rip from a tenfive a few weeks ago. i thought i'd torn a rend in the fabric of spacetime.
Polymerhead
09-21-10, 18:58
I shot about 200 rounds through my 11.5" SBR last weekend and forgot my muffs, so I used earplugs. I had a definite ringing and music sounded strange for about an hour after. I will definitely not forget my muffs from now on, and would hate to shoot it indoors without ear pro.
That being said, I've never shot any other ARs with plugs alone, so I don't know the difference.
What plugs are you using? Decent plugs are much quieter than most ear muffs. The KEY is getting them into your ears correctly.
My problem is that those orange mushy plugs work TOO GOOD. I can't hear anyone else around me when I have them in.
The shorties are very loud. I tried firing my 10.5" between two other guys with 10.5" guns with only Ear foam ear plugs. That lasted one string and I ran for my muffs. It was painful.
I shot about 200 rounds through my 11.5" SBR last weekend and forgot my muffs, so I used earplugs. I had a definite ringing and music sounded strange for about an hour after. I will definitely not forget my muffs from now on, and would hate to shoot it indoors without ear pro.
That being said, I've never shot any other ARs with plugs alone, so I don't know the difference.
:confused: I used to shoot my .50 all day with only cheap wally world plugs with no issues. Maybe they were not in right. And BTW, my 11.5" BCM has very little muzzle blast. Well, to me.....
There is not too much you can do about blast short of using a can, it is just a matter of physics. You can reduce flash, but blast is what it is.
The original moderator on the XM177 - 10" barrel - was a bit shorter than later versions and had no provisions for flash suppression. The moderators on the XM177E1 - 10" barrel and the E2 -11.5" barrel - was a bit longer and had flash suppression slots in it. The moderators reduced sound signature by approximately 1.5 db (according to the ATF making them suppressors in their eyes), and with the chambered design reduced blast significantly over a birdcage.
i left mines sittin on a table 30 feet behind me and let one rip from a tenfive a few weeks ago. i thought i'd torn a rend in the fabric of spacetime.
hahahahahaha
that is sig worthy right there
sweatpants
09-29-10, 09:45
What is muzzle blast like firing 5.56 through sub-14.5" barrels? I just discovered that AR pistols are a possibility in CA (SBRs are definitely not allowed); I was wondering how unpleasant they are to shoot. In the Vietnam era, the 10.5s had that long sound moderator attached, which made them practically 14.5s, but with the Mk18s this does not seem to be an issue. What are your impressions?
http://sphotos.ak.fbcdn.net/hphotos-ak-ash2/hs197.ash2/46068_10100305810994190_7939027_64149117_5188540_n.jpg
http://i56.tinypic.com/28v7yft.png
11.5" with AAC Brake
I fired my 10.5" once resting on the side view mirror of my pickup and the muzzle blast comming out of the side of the flash hider blew the mirror housing off.
11.5" with AAC Brake
I can only imagine how loud that would be.
I fired my 10.5" once resting on the side view mirror of my pickup and the muzzle blast comming out of the side of the flash hider blew the mirror housing off.
not SBR, but i fired a round of 7mm magnum from a 20" over the roof of my car when i was like 18... i had an 86 cutlass supreme with the vinyl top- tore out a big ass flapper. i taped it down with duct tape, but it was a long drive home and by the time i got there, it'd torn back to the rear window.. looked like my car had a big white superman cape
SBRs are supposed to have muzzle blast and be loud!
http://www.bravocompanyusa.com/v/vspfiles/photos/EAG%20TSS%2004%20DREAM%20Gray-2.jpg
SBRs are supposed to have muzzle blast and be loud!
I say the best use of an SBR is to keep the OAL manageable with a silencer attached.
Yeah my SBR with FSC556 is loud at the indoor range, but only till I light off the 7MM Mashburn. It's all relative.
wild_wild_wes
10-01-10, 21:12
I've seen pics of those guys with Mk18s in operational areas and don't see how they can fire them without ear pro...
http://img488.imageshack.us/img488/8406/42ui7.jpg
It appears the first shooter is using plugs.
Polymerhead
10-02-10, 21:21
What plugs are you using? Decent plugs are much quieter than most ear muffs. The KEY is getting them into your ears correctly.
My problem is that those orange mushy plugs work TOO GOOD. I can't hear anyone else around me when I have them in.
Don't know what to tell you. I've been shooting for years and plugs never work as well as muffs for me. I have significantly better-than-average hearing (verified by hearing tests) to go with my 20/400 eyesight and am extremely sensitive to high frequencies - it's a continual issue with my wife because I always complain the TV, music, etc. is too loud.
So I guess I'm saying that plugs very well may work better for the average person, but they have never worked as good as a quality set of muffs for me. And yes, I'm sure I'm putting them in right. ;)
You don't just hear it with those shorties you feel it. One of my firearms instructors tapped the bone behind my ear an said sound comes in that way too. I prefer the muffs too. I just used electronic ear muffs for the first time last Sunday. They were awesome and. It even a great pair. They were thin enough to shoot a long Gun. I have ditched muffs in the past because of stock weld issues. These worked well. I can not remember the model.
wild_wild_wes
10-02-10, 23:38
I put a 16" barrel on my AUG and the blast was horrendous, like a concussion in the face- because the barrel was shorter, and the muzzle was that much closer to my face. Sold that damn barrel right away.
Depends on ammo, too.
Shooting hot loaded NATO stamped 5.56 stuff, I get a flash like a frigging nuclear explosion and a concussion like a mulehoof to the chest out of my 10.5 (Battlecomp FH).
Shooting my usual plinking crap, Wolf & no-name local reloads, no flash whatsoever in daylight. If you are the observer to the 9 o'clock...watch out! ...:p
So I guess I'm saying that plugs very well may work better for the average person, but they have never worked as good as a quality set of muffs for me. And yes, I'm sure I'm putting them in right. ;)
I run both, and like both. But hands down plugs work better for me. The orange plugs are rated for a greater Db reduction too. I just run standard muffs.... no electronic stuff.
I sometimes go with muffs so I can better hear the long range gong hits. I can back the plugs out a little, but I prefer to use them properly in place.
I use a Levang Comp on my 7.5" and 10.5". It directs the blast down range. Makes it better on the shooter and those beside him.
It's not a flash suppressor but I've never been bothered by the flash.
I would think the Levan would be Calif. legal.
Here's mine.
http://www.hunt101.com/data/500/medium/AR_Pistol_001.JPG
Here's a link:
http://www.midwayusa.com/viewproduct/?productnumber=524840
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