20 cals - 20 250 improved & 20x47L load work

[mghoodlum]

I've been testing two new 20 cal magnum I plan to use for coyote hunting. I started off with 20x47L and RL-17. The loads maxed out around 42.5 grains at a little over 4200fps. Most accurate loads were at 41.0 and 41.5 at 4125 to 4150fps. I was shooting 38gr unmussig bullets.

Next I shot some fire form loads in the 20 250 improved with 40 grains of 748 and 39 grain Sierra's. Pressure was a bit high on these but not excessive. The real surprise was the velocity! These were humming along at 4500fps. Unfortunately most of the bullets didn't make it to the target.

I forgot to mention that both barrels are 1:12 twist.

I'm thinking I need to try the 748 in the Lapua as well. I thought it was going to be a bit fast for these case capacities and bullet weights but it may be just the ticket and I have about 16 pounds of it. More than enough to burn up both barrels.

I purchased both of these while waiting on my 20 chupacobra that is being built. It's based on a 22 250 improved with the addition of the shoulder moved forward as well. After today's testing I'm thinking I may be able to get about 4700fps with the Chupacobra and the Unmussig bullets.

Lessons learned: W748 may be a great powder for this capacity and bullet weight. 39g Sierra's will not withstand 4500fps Back off fire form loads to 38 or 39g.

 

[cmillard]

have any pics of your rifle along with loaded ammo? i am not suprised at all that the sierras were blowing up. have you tried berger .20 bullets?

 

[Catfish]

I am a fan of Sierra bullets and shoot more of them than anyother brand, BUT, their 20 cal. bullets just are no good for game larger than groundhog in my oppenion. Their bullets have a jacket that is .009 thick, where the Hornady bullets have a jacket that is .014 thick. I don`t know the thickness of the Berger bullets, but they hold up to the thicker skinned game and seem to preform best on it.

 

[ab_bentley]

Come on over: http://www.saubier.com/forum.html

Adam

 

[mghoodlum]

Come on over: http://www.saubier.com/forum.html

Adam

I signed up long ago but for some reason I can't post and did not get a response yesterday when I tried to report the issue otherwise I'd love too.

I am a fan of Sierra bullets and shoot more of them than anyother brand, BUT, their 20 cal. bullets just are no good for game larger than groundhog in my oppenion. Their bullets have a jacket that is .009 thick, where the Hornady bullets have a jacket that is .014 thick. I don`t know the thickness of the Berger bullets, but they hold up to the thicker skinned game and seem to preform best on it.

I shoot them in a 204R and they do a great job on yotes. That is only running about 3400fps (short barrel and reloads)

have any pics of your rifle along with loaded ammo? i am not suprised at all that the sierras were blowing up. have you tried berger .20 bullets?

I'll see about pics. The rifle is a Winchester 70 with a factory varmit contour with a Shilen match barrel. I've got several other bullets but the Sierra's were my favorite in 204R. I plan on using the 38g Unmussig's on game.