Magnum Primers in S&W .40

[Historian]

I know that I need to reduce my charge by 10% or more but are there any other problems associated with using magnum SP primers in an M&P .40? Right now, with standard primers, I am using 5.2g of W231. If I drop 3/4g will that be sufficient? I have been told by my guy at the reloading store not to use them at all but my supplier sent me magnums rather than standards and I'd like to hear what you guys think about it before I try to sell them or pay the hazmat fee to send them back. Thanks in advance.

Historian

"Democracy requires wisdom."

 

[rcmodel]

I think we covered this twice in the last week:
Heres this about that.

http://www.thehighroad.org/showthread.php?t=474128&highlight=magnum+primers

rc

 

[Historian]

Thanks rc. Been away from the computer for a couple of weeks.