Subsonic shooting, noise vs barrel length

[264win]

Has anyone compared short (16”) vs longer (24-26”) barrel lengths for noise comparison ( subsonic) in 300 BO or similar calibers?
I’m thinking of building a 300 BO with more than the usual 16” tube

 

[kindabitey]

I didn't do any noise testing, but I did run into some issues keeping 16" barrel loads subsonic in an 18" barrel. I had better luck using fast pistol powders with 135-155 gr. bullets being stupid quiet with a 16" bolt gun.

 

[KnowNothing256]

It seems to me, a guy who has never loaded or fired a centerfire sub, that if you get full powder burn in the barrel then it shouldn’t make much difference. I expect that’s why @kindabitey saw a difference: the shorter barrel didn’t achieve full burn/pressure curve until using a much faster powder, that delivers all the burn/pressure before the bullet exits.

 

[carbonbased]

I know for a fact that the sound of subsonic 22LR (1050fps) out of a long rimfire barrel (~28”) is just like the sound out of a shorter barrel with a suppressor. Maybe even quieter.

I know you asked for 300BO info but perhaps this adds to the discussion.

 

[264win]

I know for a fact that the sound of subsonic 22LR (1050fps) out of a long rimfire barrel (~28”) is just like the sound out of a shorter barrel with a suppressor. Maybe even quieter.

I know you asked for 300BO info but perhaps this adds to the discussion.

I have observed this as well, it’s what made me wonder about larger calibers.

 

[AMMOWASTER]

It seems to me, a guy who has never loaded or fired a centerfire sub, that if you get full powder burn in the barrel then it shouldn’t make much difference. I expect that’s why @kindabitey saw a difference: the shorter barrel didn’t achieve full burn/pressure curve until using a much faster powder, that delivers all the burn/pressure before the bullet exits.

If you burn all that powder in 16" of barrel and then it has 8-10 inches of barrel to dissipate heat and pressure it's going to be quieter. I have no idea if anyone has ever tried to measure actual sound levels. It's hard because of how much variety there is in 300 Blackout loads.

If you were specifically talking about a load made for that gun and barrel length I'm guessing the long barrel could be quieter but it would probably be minimal.

 

[The K]

I know for a fact that the sound of subsonic 22LR (1050fps) out of a long rimfire barrel (~28”) is just like the sound out of a shorter barrel with a suppressor. Maybe even quieter.

I know you asked for 300BO info but perhaps this adds to the discussion.

I saw a huge difference between a subsonic .22 lr out of a 20" rifle barrel and a 5" pistol barrel, so the longer barrel definitely makes a difference. I'd like to know where the edge of that is, i.e. when the powder has all burnt out, to get the optimum length (minimum) that works. Any idea? thanks all.

 

[AMMOWASTER]

I saw a huge difference between a subsonic .22 lr out of a 20" rifle barrel and a 5" pistol barrel, so the longer barrel definitely makes a difference. I'd like to know where the edge of that is, i.e. when the powder has all burnt out, to get the optimum length (minimum) that works. Any idea? thanks all.

It's something you'd have to figure out for each load there isn't a rule. Too many variables.

 

[FuhQ]

Has anyone compared short (16”) vs longer (24-26”) barrel lengths for noise comparison ( subsonic) in 300 BO or similar calibers?
I’m thinking of building a 300 BO with more than the usual 16” tube

Yes. My 22" .308 Win with subs is quieter than my 16" .308 Win with the same subs and same suppressor.

Personally, I think it would be a waste to build a .300 BLK with anything more than a 16.5" barrel. It already shines in a 10.5-16" barrel, like it was designed to. Anything longer would be running into diminishing returns, and negating the purpose of the round...Which is for good performance from shorter barrels. With the .300 BLK, and a 16" barrel... The quality of the suppressor you run will make a HUGE difference. For example, the Sandman-S is a great can, but it only has 5 baffles, so it does have some first round pop, and it's much louder than my 7" precision rifle cans that have many more baffles, like my Otter Creek Labs Hydrogen-S 7.62, which has 9 baffles and is solid titanium. It's ridiculously lightweight and pretty much hollywood quiet. If you're looking for the perfect .300 BLK suppressor, the Hydrogen-S 7.62 is the best one I've found. Plus, you can also use it on all your other rifles, as well. It's rated up to .300 Norma Mag.

They're out of stock right now, but the owner of OCL said they're built and waiting on the ATF Form 3's to clear, so they should be getting them on the shelves within the next week or 2.

Otter Creek Labs Hydrogen-S 7.62mm

Otter Creek Labs Hydrogen-S 7.62mm

www.silencershop.com

 

[hafejd30]

The thing with .22’s is they hit max velocity then begin to slow back down. Which is why they sound impressive out of a Ruger MkIV and a 26” tube. While a 18” may hit the sound barrier and cause the supersonic crack. Mine do that anyways

My 300 BO is a 8” barrel. You may find the same load in a 16” barrel hits supersonic speeds and you’ll get the crack as well.

Keep it in subsonic ranges and it will be great. My 8” AR sounds like a nail gun going off

Just my personal opinion I think sub 300 BO is a waste. Fun to shoot but a 8” and 26” barrel if kept subsonic will have the same effect down range. Which isn’t really impressive. Think I’d opt for a 45 acp and keep it short or step to a 308 with subs if you’re willing to go that long. Then supers have more effective range as well

 

[zeroz]

I saw a huge difference between a subsonic .22 lr out of a 20" rifle barrel and a 5" pistol barrel, so the longer barrel definitely makes a difference. I'd like to know where the edge of that is, i.e. when the powder has all burnt out, to get the optimum length (minimum) that works. Any idea? thanks all.

Was the pistol a semi and the rifle a bolt gun?

 

[NHPiper]

I am using N110 with 220 Noslers with great subsonic success out of a 16" barrel. Real quiet. Not enough gas to cycle a semi auto reliably but perfect for bolt guns.

Almost wish I had gone with a shorter barrel and SBRed it.