Surface Bearing Area

[Southern Shooter]

I have two .45 caliber cast boolits. One, is a traditional 250 grain round nose flat point design. The other, is a Laser-Cast 255 SWC.

Which one has the most surface bearing area?

Thank you

[John Boy]

I have two .45 caliber cast boolits ... Which one has the most surface bearing area?
Have a set of calipers? Just measure the two

[runfiverun]

you'll have to see how much of the rn above the crimp groove is groove diameter.
[some have an invisible drive band right there]
then you can measure from there down and subtract the lube groove and crimp groove length to get your total.

I wouldn't use just the drive band length to determine accuracy or velocity potential before using them.

[Silverboolit]

If you place a boolit into the fired casing nose first, and then measure what is sticking out, you should be able to get a rough idea.

[BCB]

If you push both through a sizer and see what portion of the boolit is sized on each, that might give you some idea too...

Good-luck...BCB

[Doggonekid]

Ditto on the sizer method.

[44man]

What are you looking for? If looking to use a formula, forget it. None work. Only load work works.
I found most Laser Cast were under size to groove. Nice boolits if they fit.

[Southern Shooter]

I have been shooting an HSM 250 grain cast RNFP slug on top of 9.5 grains of BE-86 from my 1989 S&W 625 in .45 Colt. Shoots great with no signs of pressure issues.
I recently landed some Laser-Cast 255 grain SWC. I am just wondering if there would be any concern with substituting this boolit in place of the RNFP that I am currently using. I assume the best thing to do is drop back down on the powder and work my way up, again.

[44man]

OK, I see your point, maybe deeper seating. That should be the only concern not the area.

[Southern Shooter]

OK. I will check out the seating depth. Thank you.