.20 cals - 20x47L & 20 250 improved load testing

mghoodlum

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Jan 4, 2011
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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.
 
No such website exist and since I purchased this rifle here I figured this was just as good of a place as any for the post. By the way I believe the website you are referring to is Saubier.com.
 
They are interesting results. I was only thinking recently that I may have been better off going with a 20x47 instead of the 20br, due to its feeding problem. I just wasn't sure if it had even been done before. Perhaps when I burn the throat out and it needs re-chambering I might look further into it, however its only just been built and I've just bought all the loading gear for it (dammit!).
 
They are interesting results. I was only thinking recently that I may have been better off going with a 20x47 instead of the 20br, due to its feeding problem. I just wasn't sure if it had even been done before. Perhaps when I burn the throat out and it needs re-chambering I might look further into it, however its only just been built and I've just bought all the loading gear for it (dammit!).

I'm really curious how long barrels will last myself but with 3 guns I should be in business.
 
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