Sub-Sonic Rifle loads

[kgcoker]

Does anyone have loading data on any pet loads that are subsonic?

Shooting suppressed at 200-300 yard Pdogs.

308?
223?

Thanks,
KG

 

[Gee]

You need to match your rifling twist rate to a what ever bullet weight the twist is fast enough to stabilise when subsonic, effectively to keep the same rotational speed subsinic as is needed to stabilise a full power round. Have not yet tested what load gives best accuracy in a 1-10 or 1-12 308 Win., but suspect it is a round or flat nose game head, minimising the ratio of bullet length to weight, probably 150 to 170 grains, and possibly seated round nose backwards.

Can confirm 1-9 twist 308 Win will shoot one hole groups at 50 yards using 10gr Trail Boss and magnum primer with 200gr SMK. The 220gr SMK does not stabilise at 1-9, would need 1-8.

223 needs 1-6.5 twist to function sub., might get away with 1-7 but have not tested.

Can co confirm 6.8SPC shoots 115gr SMK fantasic at both sub and sonic,
if i remember correct the rifle has 1-9 twist.

Short barrels (16 inch) give less friction, hence with subs more consistent velocity.

Gee

 

[Gee]

At 200 to 300 yards, pdogs if a subsonic load has been finessed to shoot 1 hole groups at 50 yards, then for 200 to 300 yards you'll need to range find within 5 yards minimum, 1 yard best, smart phone with ballistics program, use a quality scope (S&B) (reticle hold over will never be this accurate) where you can quickly adjust the elevation in a flat plane (no left to right movement around the curvature of the tube when adjusting for height, like my 6.5-20 AO Leupold where windage moves as elevation is adjusted......) and you will need absolutely no wind, no wind at all. Its some feat to pull off.

The most totally awsome highest BC head that is stable subsonic would stack things in your favour, say 750gr A-Max in a 510 Whisper, or a lathe turned 375 VLD head.

Get it right, and a closed bolt silenced gun really is silenced just like PHUT in the movies, not merely suppressed.

Gee

 

[markm87]

10.1 gr Trailboss with a 175smk....

Although I'd just shoot supers in .223. They're quiet from the shooters position with a can.