IMR 4756 and 9mm Plated Bullets

[Timothy]

IMR gives 6.3 gr. of 4756 as being max. for 9mm 124 gr. As usual, not much info. for lead bullets is given. I’m using Berry’s 124gr. Plated Flat Point and since this is a first cousin to lead, I am wondering what you consider a safe max charge for this bullet. Out of my P01, 5.0 gr. of 4756 gives me 975 fps. and 5.5 gives 1052 fps.. I’m wanting to get to around 1150 fps. to see what effect it has on accuracy and was thinking of going to 5.7 and then to 6.0 gr. If you have any experience with this recipe I would appreciate your help.
Thanks, Timothy

 

[stans]

The 47th edition Lyman manual shows:

A 130 grain cast lead TC bullet loaded to 1.016" OAL and a max charge of 5.6 grains SR-4756 giving 1097 fps and 31,600 CUP from a 4 inch test barrel.

They also show a 121 grain cast lead TC loaded to 1.110" OAL, 5.5 grains powder charge, 1198 fps at 32,900 CUP.

SAMMI max pressure in CUP units is 33,000, so I don't think going higher than published loads is a really wise thing to do in the 9mm nor is seating bullets deep in the case, but as long as you stay at or below published, you should be fine. Plated lead bullets usually behave very much like cast lead, so go ahead and increase the charge by one or two tenths of a grain at a time and watch for any sign of pressure problems.