.451 or .452

[MoreIsLess]

How do I know if my gun, a Smith and Wesson M&P 45, requires an .451 or .452 diameter bullet for reloading

 

[m33p0n3]

You can slug the barrel and measure it if you want an exact measurement. Otherwise a .451 bullet for jacketed and .452 for lead bullets should work for you.

 

[squarles67]

For jacketed bullets typically .451 is for 45 ACP and .452 is for 45 Colt. Slugging the barrel as has been sugested is the best way to find out for sure.

 

[Cherokee]

451 for jacketed, 452 for cast. As stated, slug your barrel to confirm what size for cast. As a practical matter, either one will work, let your gun tell you which it likes.