Thread: Subsonic 300BLK Noise levels

Originally Posted by clavulanate

For those of you familiar with adjustable gas blocks: can they be easily adjusted with the rail installed? I've seen ones with the adjustment screw on the side which looks like you could easily get at it but the locking screw is still on the front/back by the looks of things?

We met with 3 companies in the USA last week who are all going down a different path to adjustable gas blocks. They are making adjustments on the BCG. These are a simple switch that can be turned through the dust cover. No need to remove your rail. Hope to have their products here in a couple of months.

That sounds interesting... I'll keep an eye out

Fired the gun again today with the adjustable gas block installed. First round was with it completely closed off and it was still about as loud as a supersonic 22LR (both to me and a bystander). Hopefully it'll come down a few notches with an Oceania can on it.

Originally Posted by clavulanate

Fired the gun again today with the adjustable gas block installed. First round was with it completely closed off and it was still about as loud as a supersonic 22LR (both to me and a bystander). Hopefully it'll come down a few notches with an Oceania can on it.

Did you chronograph the ammo?

Nah not yet, waiting for my friends chrony to get returned to him before I can do that

Originally Posted by Tuukka

Hi, I think there is a misunderstanding of my post? We have had the correct type of SPL measurement equipment ..

I fully realise you do but that many other manufacturers/enthusiasts don't.

This with 9.2 grn H110 pushing 240 smk @ 980 fps was very quiet.19.2 H110 with 110 Vmax @ 2300 not

Originally Posted by Beavis

Gas venting from the ejection port?

Yes that is one reason why people try adjustable gas blocks. @clavulanate is the brass being ejected far from the rifle?

Originally Posted by 300CALMAN

Yes that is one reason why people try adjustable gas blocks. @clavulanate is the brass being ejected far from the rifle?

I adjusted my gas block today starting from completely closed to locking back on an empty mag + an extra 1/4 turn for safety and there was no discernible change in sound. As for ejection distance I would say ~1-1.5 metres?

Originally Posted by clavulanate

I adjusted my gas block today starting from completely closed to locking back on an empty mag + an extra 1/4 turn for safety and there was no discernible change in sound. As for ejection distance I would say ~1-1.5 metres?

Yeah that sounds good 1-1.5 metres doesn't sound over-gassed so your setting is ok for the block. Maybe the Waitaki suppressor is designed for tasking the boom out of super sonic rounds and not fully silence subs? You can ask them. Some suppressors like my NEA Mini-Can are not really designed to make subs super quiet. MY MAE is heavy but does both extremely well. It has a bit of a chamber after the muzzle (over barrel) that lets the super sonic gas expand a bit before hitting the baffles. It sounds like the gas is still supersonic out of your one. Both the bullet and gas can make a cracking noise, you have to slow down both. At least that is what I understand...

Originally Posted by 6x47

I fully realise you do but that many other manufacturers/enthusiasts don't.

Gotcha, no worries!

Tuukka Jokinen
Ase Utra sound suppressors

Just got my ODL can, can't wait to try it out later today hopefully

Originally Posted by Digit

We met with 3 companies in the USA last week who are all going down a different path to adjustable gas blocks. They are making adjustments on the BCG. These are a simple switch that can be turned through the dust cover. No need to remove your rail. Hope to have their products here in a couple of months.

where does that extra gas go though? I assume they just blead some off at the gas key? even if it directed out the ejection port and fixes over gassing it wouldn't help with noise levels I would have thought. very interesting idea though

Won't know to we try them. Seems to be a popular method though.

So with the new can hornady subs are about as loud as a subsonic 22lr... pretty crazy.. the bolt slamming forward is the loudest part of it all. The American eagle subs I tried were still reasonably loud though, dunno why... so if anyone wants to buy 80 rounds of American eagle subsonic 300blk ammo... let me know