Suppressors New suppressed shooter...subsonic questions...

[SD26]

Hi, I'm new to the suppressor world. I have a YHM in 7.62 for my two semi auto rifles. I managed to get out with my carbine on Monday, and it was enjoyable. I was shooting off the shelf supersonic ammo.

What do I need to know about subsonic ammo? I have a 1:10 16" barrel on my carbine. Sounds like that would stabilize a 190g subsonic bullet?

In reading the instruction booklet from YHM, it pretty much states don't use subsonic... I would suspect a liability clause for their own protection, but I appears that many shoot subsonic rounds through their cans. Anyone have any statements of wisdom?

Thanks in advance!

 

[Heronion]

Re: New suppressed shooter...subsonic questions...

I would check any subsonic load thoroughly before shooting it suppressed. You want to watch out for keyholing. I use a piece of thick cardboard. You should see perfectly round holes from your bullets, not oblong at all. Another issue is rounds not leaving the barrel. If the breech is not fully sealed, gasses can escape backwards, leaving not enough pressure for the bullet to exit the barrel. Make sure you see/hear the impacts. Using the forward assist (if it's an AR) can help with this issue.

 

[SD26]

Re: New suppressed shooter...subsonic questions...

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bpnelson</div><div class="ubbcode-body">I would check any subsonic load thoroughly before shooting it suppressed. You want to watch out for keyholing. I use a piece of thick cardboard. You should see perfectly round holes from your bullets, not oblong at all. Another issue is rounds not leaving the barrel. If the breech is not fully sealed, gasses can escape backwards, leaving not enough pressure for the bullet to exit the barrel. Make sure you see/hear the impacts. Using the forward assist (if it's an AR) can help with this issue. </div></div>
Thanks!

Can I assume that even at 25yrs I could recognize keyholing? How many rounds of a particular ammo would be reasonably necessary for a test?

 

[Heronion]

Re: New suppressed shooter...subsonic questions...

The main concern with keyholing is that it will happen right out of the barrel (i.e. go through the suppressor at not a perfectly straight orientation and cause a baffle strike). Depending on the overbore of the suppressor, there may be no room for error. So once you work up a load/buy factory subsonic I would test maybe twenty rounds or so. If they are all perfect, no keyholing, no barrel obstructions etc they should be good to go. I would test farther than 25 yards. If your bullets are stabilized they should NEVER keyhole. At 25 yards if they are unstable it may not be obvious. I'd shoot at 100. If the holes appear perfectly round you should be safe in assuming they are stabilized.

Another thing, if you want subsonic loads do a bit of testing with a chronograph, a friend of mine bought some factory subsonic loads but his barrel was 20" and it was enough to bump the FPS up to surpass the SOS. Especially true if you live in an area like I do where I shoot -10 F in the winter and 90 F in the summer. Really screwy stuff with the speed of sound in Houghton. It can vary by as much as 100 FPS over the year based on temperature alone.

 

[SD26]

Re: New suppressed shooter...subsonic questions...

Thanks again, bpnelson!

I have 20 190g subsonic rounds from SWAmmo. Looks like the safe bet would be to get a few more and establish some data at 100 yards.

 

[Heronion]

Re: New suppressed shooter...subsonic questions...

Exactly. Besides, you should have to re-zero with your subs at 100 anyway. The suppressor will most likely change your POI once installed, so be sure to document everything so you'll be sure of your zero at super/sub and with/without suppressor.

 

[Zak Smith]

Re: New suppressed shooter...subsonic questions...

The bullet doesn't have to be supersonic for it to be loud; supersonic flow over some part of the surface can cause a "crack".

 

[karb]

Re: New suppressed shooter...subsonic questions...

Dave,
Your 1-10 barrel is excellent for the heavier 190-200+. subsonics .
I'd bet it would stabilize 160-175 nicely too. Check w/out attachments
As the above mentioned of course.

 

[Ranb]

Re: New suppressed shooter...subsonic questions...

Bullet length, twist and speed are the keys here. I have found that 220 round nose stablized just fine with a 1-10 twist at 1050 fps. You will need a chrono to ensure you get the right speeds. I like the 220RN better than the more expensive match bullets as they are just as accurate and the greater weight means more power. In my experience a subsonic 308 is only half as accurate as a match grade supersonic load.

Ranb

 

[SD26]

Re: New suppressed shooter...subsonic questions...

Thanks again, guys!

Ordered a couple more boxes from SWAmmo... And they had it in stock, AND shipped it the next day! I think they might have their inventory rotations and production all taken care of!