Cast vs jacketed?

[Tom-ADC]

Lets assume you have two projectiles one cast and one jacketed both weight 150 grs, if loaded with the same primer, powder charge which would develop more FPS and pressure? Not max loads but starting loads? Say .30 cal if that makes sense.

[madsenshooter]

The jacketed bullet would develop more pressure, less velocity. The cast bullet would produce more velocity and less pressure. It's easier for the gas to deform the cast bullet and push it out the bore in comparison to the harder jacketed bullet.

[quilbilly]

In general I have found that the cast boolit has 10% more velocity but that may depend on the lube. I am currently using liquid Alox.

[gnoahhh]

That 10% has been my experience also. Checked with moderate hunting loads in .30/30 and .303 Savages, using Javelina 50/50 lube and bullets in the 11-13 bhn range. I never made the comparison in any other cartridge.

When I made the comparison I jockeyed the weight of the bullets (170 gr.) with a file to weigh exactly 170 gr. with gas check but no lube. (I wasn't concerned with accuracy, just velocity.) Did I trick myself by not including the weight of the lube?