Is there really a difference between +P brass and original brass? Can +P loads be safley used with standard brass?

A guy at a gunshop told me today that he thinks they just mark them so nobody uses the higher pressure loads on weaker actions.

I can tell you in 45acp that the +P brass from Starline is thicker with less internal capacity. The 45 Super and 460 Rowland brass are just like the 45acp brass [460 Rowland .15" longer] and fail under overload at the same load as the 45acp brass. The +P brass fails at a higher pressure, but becuase of the lower capacity, this is a lower velocity. The advantage for the +P brass is in poorly supported chambers.

0) 45 acp................. 185 gr 7.6 gr AA#5 jams w/stock Patriot
spring
1) 45 acp..................185 gr 10.2 gr AA#5 1100 fps 18,000psi
2) 45 acp +P...............185 gr 10.8 gr AA#5 1200 fps 21,700 psi
3) 45 Super................185 gr 12.4 gr AA#5 1312 fps 28,000 cup
4) 460 Rowland............ 185 gr 14.5 gr AA#5 1500 fps 38,800 cup
5) Easy extraction ........185 gr 15.0 gr AA#5 1868 fps 35kpsi *rifle
6) Case starts to stretch..185 gr 15.2 gr AA#5 1886 fps 37kpsi *rifle
7) difficult extraction ...185 gr 16.0 gr AA#5 1956 fps 42kpsi *rifle
8) primer falls out .......185 gr 16.5 gr AA#5 1998 fps 45kpsi *rifle
9) accurate heavy bullet...230 gr 13.0 gr AA#5 1662 fps 52kpsi *rifle

* Quickload estimate

[ 11-09-2002, 08:43: Message edited by: Clark ]

Thanks Clark, but I should have specified Im actually looking for input Re; the 257 R +P. I expect the facts for it are similar to your findings as well though.

Wstrnhuntr:

The +P .257 Roberts brass I have, Federal and Winchester, are heavier and have less internal capacity than the standard .257 Roberts brass. A couple of loading manuals point this out in their load data. For me max loads in the +P seem to be a couple of grains lower than in then standard case. When loading with bulky powders in the 257 I use standard cases as the 4831 like powders require the extra space.