Originally posted by robotoid:
I've read elsewhere here that a non thumb safety CANNOT be retrofitted with one, per S&W. Personally, I found the trigger on the S&W M&P I shot to be too light (IMO) for carry without a safety. I still prefer my Glocks, where I can set the trigger pull myself by changing out springs and connectors, which is not possible on the M&P's. As much as I like the S&W name, I'll be sticking with my Glocks for pistols.