I bought a SIG MPX 9mm pistol (8 inch) and went the SBR route. Recently got an AAC Tirant 9mm suppressor. Bought a 4.5 inch barrel and most of the suppressor is inside the OEM handguard. Mounted a C-More red dot (the original style popular in USPSA Open). In fact, I just got home from the range and I ran about 200 rounds of my 124FMJ reloads through the combination. I really enjoy it and I have had not any issues with the MPX - please note that my MPX is "stock" except for the 8 inch barrel replaced by a 4.5 inch barrel. It is really neat with the 147 reloads.