.308 subsonic load data

TXCOONDOG

TXCOONDOG

Well-known member
Looking for subsonic load data for a 700 with a 26” barrel and 1:12 twist in .308.

Being that the rifle is a 1:12 twist and shoots its best accuracy with velecities of 2650-2700 fps with 165 grain sst, not sure if it will stabilize (key hole concerns) at subsonic speeds ?

Bullet weight ranges: 155-165 grainers
At this point, just looking for plinking loads in the 1050-1075fps range.


 
I'd give Sierra techs a call. Years ago, they suggested a very light load (but not sub-sonic) for 30-06 using Unique behind a 168 gr. match king that would shoot one hole @ 100 yards. It was just over the starting load listed for 165 gr. lead bullet in an old Lyman book. No recoil at all but groups opened up in fishtailing or gusty wind due to low velocity (between 1700-1800 fps.)

Regards,
hm
 
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My closest 308 handload to what you're looking for is 180 SST over 11.5 gn Trail Boss (TB), COL 2.710 for 1080 fps with an 18" A-bolt.
As I recall it was 1.5 MOA at best, but didn't work with it that much.
TB is made for this application, wouldn't try an other powder.
You may know this, but subsonic load work starts high working down in powder until you get the magic fps.
I'd start at 12.0 10.5 gn TB and step down by 0.2 gn until subsonic fps is achieved.

Because of your 26" barrel, you may want to start lower at 10.5 gn TB (based on QL), then work down in powder.
 
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Originally Posted By: TXCOONDOG..subsonic load.. a 26” barrel and 1:12 twist in .308.
....Bullet weight ranges: 155-165 grainers...
That 1:12 twist is going to be an issue.

I'm going to try a HDY 160 FTX subsonic in my 1:10 twist, it should stabilize ok (1.82 SF).
That bullet in a 1:12 at 1080 fps is marginally stable (1.27 SF).
The "stubbier" the bullet, the better chance it will stabilize for your 1:12, it should be fun to try them out.
 
Plopped some slow 160 FTX 308 down-range 100 yards today.
1091 fps from 160 FTX, 10.10 gn Trail Boss, COL 2.660", HDY brass, F210M, in my 18" A-Bolt.
Accuracy was ok, (A) ~1.4" spread on 5 shots with magnetospeed hanging on,
and (B) ~2" on 5 shots with a can hanging on (very quiet,less than a 22LR).
There were no keyholes.
To get 1080 fps I will load 9.90 gn TB, via QL.

Same gun/can & projectile @ 2500 fps was 1" spread.
 


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