Polygonal Rifling and HC Bullets

[schmeky]

I shoot only hard cast bullets. My HK USP 45 shoots my pet handload very accurately (200 gn LSWC over 4.9 gns of 231). The only problem is I'm experiencing a little leading at the very front of the throat.

I've tried a 12 and an 18 brinell hardness bullet sized at .452". I wonder if a 20-21 brinell HC bullet would exhibit less, or no leading? I am also wondering if a slower burning powder may help?

Please don't recommend copper coated or FMJ bullets

 

[LiveLife]

I've tried a 12 and an 18 brinell hardness bullet sized at .452". I wonder if a 20-21 brinell HC bullet would exhibit less, or no leading?

My retired local caster made 24 BHN bullets that lead the barrel with the same load. Too hard of bullet with not enough obturation and gas cutting occurred. When I switched to 18 BHN bullets, leading decreased.

I'm experiencing a little leading at the very front of the throat.

You mean near the chamber end and not the front of the barrel? Could you try increasing the charge to bump the bullet (obturate) more for tighter seal?

 

[rcmodel]

I have shot pure Linotype (BH22) lead bullets sized .401" in my Glock 23 for going on 15 years with no Kabooms, no problems, and no leading.

rc

 

[dwhite]

Schmeky,

Really, that sounds about normal. My Glock and my Sigma lead in the same area but it doesn't get excessive or continue to extend further up the barrel. I don't know but I suspect it's from blow by from combustion of the powder until the bullet gets enough resistance in the barrel to expand and seal the bore.

All the Best,
D. White

 

[frankge]

I have shot home brewed cast bullets - not sure what hardness. Wheel weights water quenched. They are the Lee TL230's. I run these over 5g of Bullseye and have the same minor leading issues in the beginning of the barrel like you do. After 200 rnds nt too bad. Nothing a chore boy can't clean. BTW - HK USP .45 - I have never loaded a lead bullet that did not lead and stopped chasing that around anyway.

 

[schmeky]

Thanks to all for the responses. If this is typical (for the USP), then I'll stop chasing after something I will probably never catch. The 18 BHN's do better than the 12's, so I'll just keep using the 18's.