Subsonic load for .308 Rem 5R 24" Milspec?

[drail14me]

First off, I've been lurking and reading this forum for a while but this is my first post here. I've learned a lot but still have questions so I thought I'd post and ask.

I'm shooting a Remington 5R 24" Milspec rifle. This thing will drive tacks with 168gr and 175gr Federal Match ammo at 200-300 yds.

However, I most enjoy shooting subsonic suppressed at 100 yds.

I've been using CorBon .308 Win 185gr FMJ-RBT Subsonic rounds. So far, the best I can get is a 4" group at 100 yds.

I've read tons of info about trouble getting subsonic rounds to stabilize from Remington 5Rs and am wondering if that is the cause of my large grouping? I don't see any keyholes on my target but wondered if it was a stabilization problem?

I've read a few threads in the group about trying some custom load for this rifle.

Has anyone found a good subsonic load for the 24" .308 5R Milspec that will group better than a 4" group? If so, would you mind sharing?

 

[Bugholes]

Re: Subsonic load for .308 Rem 5R 24" Milspec?

It's not for the milspec 5R, but you might try trailboss under a 155 Sierra or Scenar. 9.5 grains comes to mind

 

[drail14me]

Re: Subsonic load for .308 Rem 5R 24" Milspec?

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: bugholes</div><div class="ubbcode-body">It's not for the milspec 5R, but you might try trailboss under a 155 Sierra or Scenar. 9.5 grains comes to mind </div></div>

Thanks. We may give that one a try.

I'd read where the 11 1/4 twist barrel on the 5R Milspec is where the issue is and that it takes a heavier bullet to stabilize. Not sure though. Hopefully, someone on here has had success with this same rifle and subsonic.

 

[drail14me]

Re: Subsonic load for .308 Rem 5R 24" Milspec?

Anybody had success with subsonic in .308 for the Remington 5R Milspec??????

 

[jsthntn247]

Re: Subsonic load for .308 Rem 5R 24" Milspec?

Migt want to try some heavier bullets. Start at 12 grains and work your way down using a chrony.

 

[bohem]

Re: Subsonic load for .308 Rem 5R 24" Milspec?

Ask flounderv2 what he's shooting for subs in his rifle but I seem to remember he's a touch under 11.0gr of Trailboss under the 180 Hornady RN.

With the 11 1/4 twist rate in there it cuts you short on what you can use for bullets, but I know that a 150gr GameKing or PRVI 150gr PSP will stabilize over 9.5gr of Trailboss from a 12tw too.

For just shooting targets with subs the 150's are dandy.

My 308 was built by Ozzie Suarez with an 8.5tw in it, I shoot cast 250's at subsonic speeds.

ETA: ALWAYS DO LOAD TESTING WITH THE SUPPRESSOR OFF TO VALIDATE STABLE FLIGHT, only once you're shown stable, circular holes in paper at 100yd or further should you put the suppressor on it.

 

[Deadshot2]

Re: Subsonic load for .308 Rem 5R 24" Milspec?

It's all about "stability" of the bullet which is determined by RPM's as it's in flight.

Here's a calculator that will help show whether a bullet is stabilized or not and at what level(Minimal to Maximum)

Bullet Stability Calculator.

It's not just bullet weight but also bullet length.

A 168 gr bullet measuring 1.180 will stabilize at speeds over 660 fps with the 5-R twist rate. This calculator will take some of the "guess" out of "which bullet".