Velocity Increase with suppressor

[Dlet1080]

First post on this forum:
I'm wondering what kind of velocity increases people are seeing when using a suppressor?
I've loaded 10 rounds of 225 grain Hornady boat tails with 8.7grains of H110, velocity without can = 420fps average, velocity with can = 947fps average.
I'm using a Ruger American ranch in 300 blackout, 16" barrel
Caldwell chronograph... Is this chrono reading error?

[CanOfWhooppass]

That kind of velocity increase isn't remotely posible from adding a suppressor. What velocity does your loading manuel predict for that load, if your not within 10% something is wrong with your chrony.

[Fulliautomatix]

420fps? There's something terribly wrong with that velocity reading.

Per Hodgdon's reloading website:
9.9 grains of H110 (max load) should push a 220gr SIE HPBT up to 1050fps
9.5 grains of H110 (max load) should push a 230gr BER TACT up to 1085fps


I'd say either your chrony is faulty, or your load is too low and you're getting erratic velocities. I'd pull the bullets and start over with more powder AND/OR check your barrel for obstructions after every shot until you get consistent velocity readings.

The proper way to load that kind of round (subs with only max load data) is to start at the max load and decrease until you see the velocity/accuracy you want and the bullet stabilizes (as evidenced by clean holes (no yawing) on close range targets). Those are pretty heavy/long bullets, and that gun has a 1:7 twist rate, so that's good... but all the same no sense in risking a baffle strike. Assuming your chrony is OK, when you see velocities vary that much, you're on the verge of plugging your barrel. If it were me, I'd load up 9.7 grains of that powder behind your bullets and see what velocities you're getting, without the suppressor. Just leave the suppressor off until you get the velocity issue nailed down.

Did we mention that the suppressor is a red herring here?

[Killerapplesauce]

Ya agree those numbers are a little fishy. I would chronograph your loads again and see what numbers you get. What type of chronograph are you using?

[T-Rex]

Before I saw 16"bbl, I thought you were using something uber short, so the powder was still burning in the suppressor or the unburnt was messing with the chrono.
The lowest I've ever seen was a 45 Colt, from a 2"bbl, @500fps.
My 308, 1:10 twist, starts to squib around 750fps (jacketed)

How far is the chrono from the muzzle?
Are you shooting outdoors? How is the cloudcover?
Are you using artificial light? Once I stuck those push-lights to the underside of my chrono's reflectors I started seeing more consistent readings.

[a_canadian]

My guess is that the 420fps is a typo, that he intended to write 920fps without a suppressor versus 947fps with one mounted. But of course until he comes back to respond we can't know for sure.

[Tony M.]

My guess is that the 420fps is a typo, that he intended to write 920fps without a suppressor versus 947fps with one mounted. But of course until he comes back to respond we can't know for sure.

That's my suspicion as well.

[Fulliautomatix]

Think he has 420 on his mind?

If so, probably shouldn't be reloading.

If not, the 9 and the 4 aren't really prone to interchanging on the keyboard.

[Joshua@CapitolArmory]

Yeah, I second that the 420 doesn't seem right. Honestly, I would be very cautious of shooting anything that slow--- someone knows more than I do about the friction between the specific projectile and the barrel on here.

It seems like you could potentially be getting into squib territory, or baffle strikes (why it's a risky idea to run CB through a rimfire can).

[Wicked]

First post on this forum:
I'm wondering what kind of velocity increases people are seeing when using a suppressor?

https://www.full30.com/video/6873166335 ... 20067599f4


The theory of "Free Bore Boost" doesn't check out with reality in their example. Your mileage may vary.

[sucker76]

That was a cool video . I got different results from my very limited testing.
I got an average of 3063 with standard deviation of 28. With the suppressor on it was an average of 3108 with standard deviation of 6.
The gun was Windham Weaponry 16" 5.56. Ammo was American Eagle Lake City made 55 grain. Suppressor was a Saker 762 with brake QD.
I only shot 3 rounds each. I understand this is a pretty insignificant sample size. The velocity increase could have been ammo temp differences eventhough i kept them all in the shade.
I also found this article
http://precisionrifleblog.com/2013/07/1 ... -velocity/


Food for thought.