Lead Bullet vs XTP bullet powder grain question

[Jamesmb]

I was wondering why using the same powder, the starting and max loads for a 158 grain lead bullet would be less then that for a 158 grain XTP or JHP bullet? Is JHP the same as XTP?

 

[Mark whiz]

A XTP bullet IS a JHP (Jacketed Hollow Point). Some loading data show a little lighter loadings for XTPs although I'm not sure why, most every caliber I've tried them in responed well to standard JHP loads.

Lead bullets are another matter though. Exposed lead and a copper jacket have different qualities affecting their speed down the bore, etc. You also have to watch pushing lead bullets too fast to avoid heavy lead residue being left in the bore after shooting.

 

[ForneyRider]

delete.

 

[FieroCDSP]

The "too fast" being refered to is actually "too hot". The higher pressure does give you higher speed, but it also melts the back end of the lead bullet which causes it to deposit or lead the barrel. Lead is inherently more accurate because of this quality, though. You seal more gas behind the bullet, it forms to the grooves better, and thus your accuracy. The trick is to find that magic recipe that provides the best velocity, the best accuracy, and is just below the threashold of melting the bullet. There's formulae for figuring Brinell Hardness to max pressures and such. Some cast manufacturers provide that number for their bullets, as it's determined by alloy and testing per batch.