Suppressors affecting velocity

Dustin Ellermann recently conducted a simple test in which he shot various firearms of varying calibers through a chronograph with and without suppressors on each, in order to test their velocity. The overall findings are that, yes suppressors will increase the velocity of a round, with the exception of the .223 in his specific test, mostly with an average of by 18 Feet Per Second (excluding .223). I’m no ballistics guru by any means, but I would just be curious as to what the chronograph is calibrated to and how accurate it is. Because those figures are pretty minute in the overall scheme of velocity, so in the end, does this really matter when it comes to point of impact? I do know, working with 7.62 M40A5s and M110 SASSs in a Marine sniper platoon, that it was common knowledge that two factors would raise the point of impact- a suppressor mounted, or higher temperatures in the weather from previous shooting. So if we started shooting on a cold morning, and continued shooting throughout the day when it would get hotter, our point of impacts would rise. However, these changes weren’t evident until ranges of perhaps 400 yards and beyond. So that makes a large difference with precision rifles out past 400, but most shooting in general is done at probably 300 and in, of firearms of all calibers. So whether or not this will affect your shot at 150 meters while deer hunting, it probably won’t. Either way, good tidbit of knowledge.

The difference was somewhat negligible being an average of all calibers (including the .223 which actually decreased by 11FPS within the 5 tested rounds) of 13FPS increase.  If you were to leave out the .223 which threw a wrench in the test the average increase would be 18 FPS.  Still, hardly enough to come into play until you reach several hundred yards out.  But it does prove that a suppressor will increase velocity and not decrease it.

The velocity results, mostly measured with 5 rounds without a suppressor, 5 rounds with:

 No Suppressor Suppressed Change: .22LR 1001 1022 +21 9mm 1259 1281 +22 .300 BLK 2134 2147 +13 7.62x39mm 2158 2175 +17 .223 Remington 2968 2957 -11 .308 Winchester 2495 2515 +20 .338 Lapua 2956 2968 +12 Average: +13 Average (no 223) +18

Miles V

Former Infantry Marine, and currently studying at Indiana University. I’ve written for Small Arms Review and Small Arms Defense Journal, and have had a teenie tiny photo that appeared in GQ. Specifically, I’m very interested in small arms history, development, and Military/LE usage within the Middle East, and Central Asia.

If you want to reach out, let me know about an error I’ve made, something I can add to the post, or just talk guns and how much Grunts love naps, hit me up at miles@tfb.tv

• Machinegunnertim

Velocity drop from .223?! Anyone got an explanation for that?
I suppose barrel lengths will affect things significantly.

• Drew Coleman

I wonder if it was just a freak variation in the ammo? I’d kinda like to see that one done over.

• NDS

I’d love to know more details, I have a 10″, 14.5″ and 18.5″ in 5.56 that all run hotter suppressed. I’d have to check logs but it’s a percentage, like the 10″ runs 10ish faster and the 18.5″ runs about 20ish faster. Not sure what would cause the drop, maybe it was a 7.62 can? Still don’t know how that would slow it.

• Mark_KTO

Possible turbulence in the can, but that would also result in a loss of accuracy.

• TechnoTriticale

I actually would not have had a guess on suppressor velocity effect.

Depending on powder used and barrel length, powder might still be burning while the projectile is transiting the can, providing extra boost.

The can confines the gasses to some extent, protecting the projectile from experiencing full atmospheric drag, and thus merely delaying velo drop. Conversely, air ahead of the projectile in the can is also confined, and might provide a back-pressure spike. So this argument cancels itself out and you may forget that you read it.

So yeah, barrel length, caliber, loading, can length, bullet design, can design, weather, altitude, can temp, roll the dice.

Worthy test. Good for months of web chatter, and yes, a mil sniper would need to have full command of the problem.

• Martin Grønsdal

maybe the chronograph should be further down range? like 20 feet away from the muzzle to mitigate any possible effect that you mention?

• Mark_KTO

No.

1. The important thing is that the measurements are taken consistently. Muzzle velocities are all measured just in front of the barrel. Taking it 20 feet downrange makes those measurements uncorrelated to standard measurements.

2. Nothing in what he suggested would make any difference once the projectile exits the muzzle, so there is nothing to be gained by moving the measurement point.

• Pseudo

I REALLY wish the people would do proper statistical analysis when they were conducting tests. Some of these comments could be addressed by looking at the standard deviations. Student’s ts would give us a good idea on the confidence that could be placed in those average ie: how likely is it that the difference in averages can be attributed to variance from ammunition alone. I love empirical testing and applaud it, but you can’t draw solid conclusions without basic stats. I already posted on the original link asking them to provide all of the data.

• mud

That stats class in college continues to pay off.

• PeterK

I came hete to say basically the same thing, haha.

• Major Tom

Battlefield games are lying to us!

• Griz

Definitely something that has pissed me off, especially considering if I was going to war I would zero my rifle with all the equipment attached.

• Christian Hedegaard-Schou

Gemtech calls this “Freebore boost”. Basically, the bullets leaves the friction of the barrel, but is still constrained to a “bore” (the bore of the suppressor) where the expanding/burning gases of the propellant still have an acceleration affect on the bullet.

• KestrelBike

No comments on the horses chillin’ in the background??