I see a good amount of 9mm AR builds with flash cans and linear comps. What are the benefits of those muzzle devices if any? I don't see them reducing recoil, I do see the benefit of using a longer handguard/rail.

Sure makes my 16 inch quiet. I feel it reduces recoil a bit but realise that doesn't really make sense.

I started out with a A2 Flash Hider, then went to a KVP Linear Comp, then back to the A2, I found no benefit to either of them and went to a Thread Protector and haven't noticed any change amongst any of them. I'm using a 7.5" barrel on my 9mm AR Pistol.

I think we see a lot of Muzzle Devices due to Most started out with 5.56 and 300 Blackout and Flashcans and Compensators are considered a Must, I used a KVP linear Comp on my 9" 300 Blackout to send Blast and noise down range and to be kind to those on each side of me at the range. I found that I don't need one on my 9mm AR, I don't have one on my Glock 19 either

Thank you snellkid: Good to know. 

I added another comment after you read my reply.

Also some are using short barrels ( 4.5"  to 5.5") and a flash can does allow for a longer handguard.

Just my humble xp ..I was running a device mentioned on my 7.5 for quite a while.  I  recently switched up to just a plain ole thread protector and a shorter handguard to lighten things up a bit, as I was doing the muzzle device slightly inside the handguard setup.

Have not noticed any differance as far as recoil and concussion going from comp to virtually no muzzle device on the 9mm sbr.  The only major differance in that aspect I have significantly noticed is from swapping out the buffer setup to one of those fandangled hydraulic buffers and spring.  Again, just my personal xp.

Wow!! I actually just read your post, for some reason it didn't load right away on my browser.....am I you? are you me?..hey me, what's my favorite color?.....p.s I like your style

I see the point of directing the noise down range. Also I thought the forward blast would increase recoil, looks like that's not the case. I am in the process of a 9mm AR build so I was going to go with a flash can, but I got a FH from Rousch Sports: Rampage XS.

I totally agree with Shifty552, A Muzzle device is not going to do squat for recoil in a 9mm AR, Recoil can be reduced in a 9mm AR by playing with the Buffer and Bolt, By modifying the amount of mass that is moving should modify the felt recoil. Heavier and lighter Bullets should also modify felt recoil.

Extends the muzzle past the handguard so I don't have to worry about shooting my finger tips off.

cochraneap I like your build, we think along similar lines.

If you look close, you can just see my Thread Protector sticking out from my 7" Handgaurd.

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Nice guys!!  ...my tp setup for s&g's

It does to the extent that the linear compensator delays and slows the gasses before they leave the compensator, which depends on the specific style of linear compensator or flash can.  


In terms of noise and concussion, it may well decrease the perceived level of noise for the shooter and for people to the sides of the shooter.  

Caliber and cartridge also matter.   For example, no one likes that guy who shows up at the range with a .300 win mag with a compensator on it, and no one wants to be stuck next to him on the range.   With a short barrel .223 or 5.56mm pistol or SBR the effect is similar given the high operating pressures of those rounds and the resulting blast in a short barrel.

The British put a cone type muzzle device on the Lee Enfield Mk V (the jungle carbine) and my impression when I owned one was that it did a pretty good job of reducing perceived noise at the sides to around the same level as the Mk III and IV SMLEs.

Colt put a moderator on the XM177E1 and E2 carbines in order to reduce the sound levels to the same level as the M16A1, which was apparently enough to cause the ATF to consider is a suppressor, a monumentally stupid move in my opinion, given how loud they still were - i.e the same as an M16A1.   But, the non baffled moderator replicas probably offer some of the same benefit as many of the current flash cans in that regard, by creating space for the gasses to expand and slow, before they leave the end of the system, and by directing the gasses forward.

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For the 9mm, I doubt the benefits are all that significant given the lower operating pressure of the round, the far smaller volume of gas being expelled, and the relatively long barrels used in many AR-9 carbines.  For example, a 10" AR-9 has a barrel twice as long or overt twice as long as a 9mm pistol, while a 10" .223 pistol or SBR has a barrel only half as long as a standard .223 rifle.

Have installed flash cans to help redirect noise and blast down range. Not sure how well that works for pistol length barrels but on 16" it does make a difference; especially with a 9mm. Can shoot my Sub 2000 without hearing protection. I still wear them but I'm not in fear of ringing if I don't. Probably not going to have time to find some ear plugs or ear muffs if SHTF.

KAK flash can to direct the blast away. Clears the hand guard and looks great.


Dave N

I ordered a decibel meter the other day.  If I get time this next week I'll see what kind of noise reduction I get next to my ear and at adjacent benches.

Ok..  I had the range to myself this afternoon so I did some testing with the decibel meter.

I tested the KAW Valley Precision KVP XL Linear comp in 9mm, the 9mm version of the KAK Flash can, and 9mm versions of the A1 and A2 flash hiders.  There was no significant difference between the A1 and A2 flash hiders so I dropped the A1 from the test.

I tested them with both my 16" PSA 9mm carbine and my 10.5" RRA pistol.

I tested with the decibel meter next to my ear, and 10' to the side (the spacing between positions at our club range).

I also did testing under the covered portion of the range, and out in the open.

16" results:

Under the range cover, measured at the ear:

A2 - 117.7, 118.1, 117.8, 118.0, 118.1 - average = 117.9 dB

KAW - 117.1, 116.3, 115.8, 115.9, 117.1 - average = 116.4 dB

KAK - 118.0, 117.2, 118.2, 119.2, 118.6 - average = 118.2 dB

bare muzzle - 119.0, 118.7, 118.3, 119.1, 118.6 = average = 118.7 dB


In the open, measured at the ear:

A2 - 114.8, 113.7, 113.9, 113.7, 114.3 - average = 114.1 dB

KAW - 114.7, 113.8, 115.4, 114.5, 114.9 - average = 114.7 dB

KAK - 116.4, 115. 5, 116.0, 115.8, 115.9 - average = 115.9 dB

The slightly louder results under the range cover (117.8 dB versus 114.9 dB) were expected.  However, the slightly louder results with the KAW linear comp and in particular the KAC flash can compared to the A2 flash hider were not quite what I expected to see.


In the open, measured from 10 ft to the side, at ear level:

A2 - 105.7, 106.9, 105.8, 106.3, 106.3 - average = 106.2 dB

KAW - 106.4, 106.9, 106.3, 106.5, 106.1 - average = 106.4 dB

KAK - 106.8, 107.0, 106.6, 106.7, 106.8 - average = 106.8 dB

bare muzzle - 106.5, 106.3, 106.0, 105.5, 106.5 - average = 106.2 dB

Essentially, from 10 feet to the side there was no significant difference between any of the devices compared to a bare muzzle.


10.5" results

Under the range cover, measured at the ear:

A2 - 118.6, 120.1, 120.6, 118.5, 120.1 - average = 119.6 dB

KAW - 118.3, 118.6, 118.2, 118.0, 119.1 - average = 118.4 dB

KAC - 121.6, 120.4, 120.1 120.5, 119.6 - average = 120.4 dB


Further testing was delayed by rain, and a need to keep the decibel meter dry, but I did get a 5 shot string with the KAW at 10' to the side, and got an average of 106.5 dB.  That's a 11.9 dB drop and is significantly more than the 8.5 dB average decrease with the 16" barrel.   That suggests more testing is probably worth the effort.

It also suggests that the higher exit gas pressures in the shorter 10.5" barrel may allow the muzzle devices to produce a greater decrease in noise levels  at 10 fee tot the side than in the 16" barrel. And in turn it suggests that the devices may be more effective with .223 and .300 Blackout cartridges given their higher operating pressures and heavier powder charges.


In 9mm, the 2 dB reduction in noise with the KAW linear comp under the range over compared to a bare muzzle in the 16" carbine was as good as it got.    And that result was less than the 2.9 dB effect of just moving out from under the range cover.

But...in general for 9mm carbine purposes, there is no significant decrease in noise at the ear or to the side in a 9mm 16" carbine with either the linear comp or flash can compared to the A2 flash hinder.  So buy one for fun or buy one for looks, but if you're shooting a 9mm carbine don't bother buying one for noise reduction at the ear or to the side.

My true purpose for using a KAK flash can on my 4" 9mm is so I can still shoot it safely without a suppressor under the 5.5" Odin rail.





I actually use a flash can or mini-flash can on ALL my 9mm carbines.  They serve as a thread protector, but the larger diameter and notched ends make them much easier to take off in case I want to suppress one, and easier to put back on securely when I'm done.

That's dismal results.

That's what I thought.  Bear in mind though that this was just 9mm.

It might actually make some difference when used with .223/5.56mm.

If you have ever been on an entry team and the guy beside you fires a 5.56 round with an A2, it makes a difference.

Dave N

Yes Dave, and we both agree it might make a difference, but show me the actual numbers.

The problem with the advertising hype is that manufacturers were claiming it made a difference in 9mm as well, when it doesn't make much, if any difference at all.

I'm also interested in how much actual measured difference it makes in an enclosed space.  Redirecting the sound forward just bounces it off the closest wall, and while that adds some distance to reduce the intensity of the impulse, I'm not sure the reduction in noise to the side is significant.  I mean, is 160 dB more tolerable than 170 dB?  No.  Both will cause permanent damage to unprotected ears.

What VFG is that?

A fleabay special.. lol!! I really liked the Arisaka but had a hard time finding one so picked this up in a pinch and kinda just rolled with it. Some guy had these on ebay for pretty cheap has held up so far.

+1 Very cool info DakotaFAL!!

Link?

Also specs on build?

ETA;

Thanks for the link, picked one up.
Nice to see sbr's in IL now.
Have 3 myself and waiting on 4th.
One of mine looks almost exactly like what you posted.

No prob buddy...now if only they can get their shit together and get the suppressor bill passed life would be much better.

I use a KAK can for alot of the same reason others guys do, to get the end of the barrel past the end of the hand guard.  Someday when I buy my suppressor, Ill remove the $20 flash can and keep it around for when I dont want to run with a suppressor.

Mine is just a thread protector for my can. The larger size over just a FH allows me better leverage to tighten it or remove it.

Well I ended up getting an 10in ALG rail for my build, so I am ordered a KAK flash can for my 8.5in barrel. Thanks for all the info.