starting a new toy.... m70 action, pushfeed single shot, suppressed.....your choice 1 of 3... bullet weights, cases, twists???... barrel will be a 22" #4 contour shilen...synthetic stock....

At the moment I own 5 target rifles in .30 BR (the cartridge about which you are speaking).

In mine I shoot mainly cast bullets of up to 215 gains, or jacketed bullets of up to 190 grains. For those bullets, I use 1-in 11" twist barrels made by Hart.

If you are going to shoot strictly jacketed bullets in IBS or NBRSA benchrest score matches, I'd personally recommend no heavier bullets than 135 grains, and a twist no faster than 1-in-14", or even better, i-in 15" or 1-in-16".

Mine shoot best with a case full to just barely below the base of the bullet of Vihtavouri N-135, though one can substitute the same quantity of Tu5000, IMR4895, or AA2495. That is 52-1/4 clicks on a Jones or Harrell powder measure. Though I have never weighed my charges, I undertand from friends who use the same volume that it is right around 29+ grains weight.

If one of those powders isn't available, then Vihtavouri N-133 or IMR 4198 works very well for me with the 135 gr. and below weights of bullets, and charges reduced a grain or two. I use Rem. 7-1/2 and Federal 205-M primers interchangeably in cases made from Lapua 6m/m BR brass.

As you can tell, I prefer stick powders in this cartridge, though some of the ball powders suitable for the .223 such as AA-2230 can be made to work very well too.

Incidentally, when I first started with this cartridge 18 years ago, and cases for it simply weren't easy to make from anything commonly available, I made mine from .300 Savage brass.

My die was a "stubby"with a set of various diameter bushings, very much like the ones Butch Lambert is closing out in the "Classified" forum here at AR right now. The resulting cases performed just great, but were a lot of work.

have you chrono'd anything??.... im looking for sub-sonic performance....

Me and a buddy both have 300 whispers on Rem 700 with cans. They are very fun. With 16" barrels our 208 amax's run 1030 with 8.2 gr of VVN110. No experience with the other calibers. With a whisper you can run 125gr bullets darn near 30-30 velocities or easily run subs and 240gr match kings if you get a 1-8 twist or faster.

Can't see any reason to go with the shortened .308's if you're running a can. The .300 whisper with a fast twist is the ticket, but the fast twist aren't friendly with cast bullets.

quote:

Originally posted by jimatcat:
have you chrono'd anything??.... im looking for sub-sonic performance....

Yes, I chrono'd pretty much everything I tried of those powder loads listed in my previous post above. In the .30-BR chambering they were definitely not appropriate for use with a sound moderator. Velocities ranged from about 1,900 fps to 2,300+ fps with gas-checked cast bullets.

They were however extremely accurate, with a few (very rare, like two groups in 7 years) 5-shot 100-yard groups in the 0.08" range, a few in the 0.1s, more in the 0.2s, and many in the low 0.3s, all with cast bullets.

With jacketed bullets, you could get the same velocities, but accuracy was pretty commonly in the 0.1s and low 0.2s from my .30, BR match rifles.

300 whisper with a 1-8" twist and use 240 smks or 208 amaxes for economy: