Quote from: sqlbullet on May 15 2021 11:00:25 PM MDT
Richard Lee's thoughts about pressure and accuracy sound really good in print, but don't actually translate to real world performance that well. ... According to the Lee method I was WAY past the pressure envelope for those bullets, but the accuracy was fine.

Thank you for your reply. I ended up getting a copy of Lyman's Cast Bullet Handbook (one of the few things not sold out out my local store). The alloys that it lists for the 10mm loadings (which include 200gr but not 220gr) are either 10-to-1 or Lyman #2, so I feel better about the BHN now.

If anyone else is trying to duplicate this round, I will also note that these Hi-Tek coated bullets failed (pic attached) Hi-Tek's acetone test.

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Use a clean rag or paper towel and moisten with acetone. Rub the test bullets back and forth for 30 seconds. If proper curing has been obtained, there should not be any of the coating removed from the bullet and the towel should be free of any colour transfer from the bullet. - http://hi-performancebulletcoatings.com/coating-instructions/

I'm not sure how important this test actually is when it comes to firing the round, but figured I'd include this info for anyone who also likes to obsess over details.

Hello,

I pulled a couple of bullets and also noted the sub-215 grain weight. I also tested the bullet hardness and am curious as to whether someone can replicate what I'm seeing. As I'm relatively new to casting, I figured I'd post here to see what folks' thoughts are.

Using the Lee lead hardness tester, I measured a diameter of 0.055" to 0.056", which puts these between 17.2 and 16.6 BHN. (I have attached an image of one of the measurements to this post.)

According to the documentation that Lee provides with their tester, 17.2 BHN corresponds to a max pressure of 22002 PSI. Given the high pressures of 10mm, I was expecting a harder bullet. Underwood's website states their hardcast bullets have a Brinell hardness of 21. (https://www.underwoodammo.com/frequently-asked-questions/). Thoughts?

Thank you.