Nosler 40 gr. B-Tip and 20 Practical

[Adam Morris]

Pat, I agree that the pressure must be up there, but have no way of measuring it save for the typical case/primer analysis. I do know that I shoot my 20 Tac. in various temps and have yet to blow up. I carefully work up to the max the particular lot of brass will take, and back off from there. This is the method that David Tubb has written about in his books and it seems to work. Regarding published load data and associated pressure; they are all over the place. A reasonable comparison as relates to the 223 vs. 222 rem mag case would be the 308 vs. 30-06. Many load manuals have the 308 out performing the 30-06. This is not reasonable unless the 30-06 is loaded to a lower pressure, which indicates that a particular cartridge may not be loaded for the pressure it can take, but may be loaded for the firearm in circulation instead.
Regards,
Adam

 

[montdoug]

I have a fair number of .20's from number 2 of the first 4 of the .20 Killer Bee's to the .20 Dasher, they included a .20 Tactical and a custom chambered minimum spec .204 with zero free-bore, all but the Dasher are 1 in 12's. Most 1 in 12's do ok with the 40's but more than a few are a bit twitchy on some 40's, particularly the fantastically explosive 40 V-Max.
On my .20 Dasher the primary goal "was" the 40 V-Max (least expensive of all 40's and way frangible too), I wanted hyper speed with big upset and bughole accuracy, with that in mind I opted for a 1 in 11 Pac-Nor 3 groove Super Match. I couldn't be more pleased.
Shot this.

With this chrono tape. Mild load pressure wise.

Any .20 I was putting together where 40 grainers were a goal a 1 in 11 twist would be my choice. Twist it for the heaviest bullet your focused on and the lighter bullets under that weight a bit should do well also.

I posted the pics to show that I agree with what's been said about high velocity, there ain't no free lunch. The .20 Dasher is a .20 BR improved to a 40 degree shoulder and picking up just under 4 grains of capacity. The load I posted is duck soup with that case capacity.
I use IMI cases in my .20 Tac with a 26 inch tube and 3,880ish FPS is the end of the earth with 40's and acceptable brass life a little slower wouldn't hurt either.
Sorry for just jumping into your thread.

 

[montdoug]

willy i've followed this idea from my smallest 20's (20Killer bee)

up to my largest

20 x 47 Lapua improved.

SDH

Howdy, do we perhaps know each other from Saubier? Wondered about the .20 Killer Bee you mentioned, thought I knew where all of em had swarmed to so far ;D. Great round huh?