308 subsonic loads

[Mathewjp]

700 VLS 308. 1 in 12 twist.

I loaded 11 gr. Trailboss, cci magnum primer, under a 155 a max. It was shooting good through my can last weekend and super quiet. I shot 20 or so. I loaded more and shot yesterday. They are tumbling at 100 yards now. I cant understand. Anyone else run into this?

 

[Zero333]

Typical of 12" twists. Need more spin.

Try a flat base hunting bullet.

 

[Dave in WI]

Pretty slow twist for subsonic. I find even the 10 twist can be problematic. 300 Blackout usually is a 7 or 8 twist and works much better. Not much help as you can't just change twist w/o barrel swap.

 

[Dave in WI]

Zero33 beat me too it!
For bullets in 308 Win subs, I've had luck with Hornady #3060 170gr FP and Berry's #73348 30-30 150gr FP

 

[Hoser]

I have had the best accuracy with Trailboss and the 125 TNTs going about 1015. This is out of a 10 twist Bartlien.

 

[Mathewjp]

Thanks guys.

I loaded 155 gr. with the slower twist in mind. They shoot great, supersonic. I loaded and shot 20 last weekend, and they weren't keyholing. Actually grouped about an inch at 100. I loaded 40 more, cleaned the bore, went and shot yesterday and they keyhole. Same rifle and load. Cant understand why the first batch didnt tumble??

 

[hunter67]

I'm shooting 11 twist with Hornady 220 RN and trailboss. The dog gone things shoot almost one hole at 50 yards

 

[AJC]

Thanks guys.

I loaded 155 gr. with the slower twist in mind. They shoot great, supersonic. I loaded and shot 20 last weekend, and they weren't keyholing. Actually grouped about an inch at 100. I loaded 40 more, cleaned the bore, went and shot yesterday and they keyhole. Same rifle and load. Cant understand why the first batch didnt tumble??

I haven't run the numbers but you might have been right on the fence of stability and environmental factors changed enough to take it out of stability you may want to run a calculator for your particular load and bullet weight

 

[dolek]

I have had the best accuracy with Trailboss and the 125 TNTs going about 1015. This is out of a 10 twist Bartlien.

Same here , great combo for my rifle .

 

[Capt45]

Thanks guys.

I loaded 155 gr. with the slower twist in mind. They shoot great, supersonic. I loaded and shot 20 last weekend, and they weren't keyholing. Actually grouped about an inch at 100. I loaded 40 more, cleaned the bore, went and shot yesterday and they keyhole. Same rifle and load. Cant understand why the first batch didnt tumble??

Maybe you shouldn't have cleaned the bore.

 

[Mathewjp]

I had a clean bore before shooting the last batch, so not sure that would do it.

Could have been environmental conditions, I suppose.

AJC, pardon my ignorance, but what calculations do I need to figure out?

 

[AJC]

https://bergerbullets.com/twist-rate-calculator/
This is a calctor to show you if your bullet will stabilize.

 

[mgunderson]

Might consider trying a shorter 150 class hunting bullet for the 12 twist. I shoot the 175 sierra match king in a 10 twist and it is ok. Your asking the 155 bullet to do something it wasn't designed too. Many older match bullets transitioned between supersonic and subsonic cleaner.

 

[lb-ft]

Berrys FP 30-30 as mentioned above is exceptional w/Trailboss in .308, 30-30, 30-06. Sauer 200 is boringly accurate with this powder / bullet combination, though I found best accuracy at max charge which IIRC puts it in 1300 FPS vicinity.

 

[Mathewjp]

Mgunderson, what bullet do you recommend I try for subs in my 12 twist?

 

[Zero333]

Mgunderson, what bullet do you recommend I try for subs in my 12 twist?

Any 30 cal that does NOT have a boat tail. No heavier than 150 gr.
If you insist on the bullet having a boat tail, then the 125 gr Nosler Ballistic Tip will work.

Sierra and Hornady make many different flat base hunting bullets like the Pro Hunter or Hornady Interlock SP and RN.
The lighter (shorter) the bullet the more stable it will be at subsonic velocities.