If you purchase a 9 mm can you get a .40 slide and barrel or do you just need the barrel. Or can you not swap at all.

Don't know the answer but I know that a 40 barrel won't work on a 9mm slide because the 9mm breechface is too small for the 40 bullet.

In doing more research it seems that if you buy a .40 you cn just get .357 and 9 mm barrels. Seems factory barrels will work just fine but there are also storm lake conversions

357 Sig is a necked down 40 case. It will work in a 40 slide and 357 barrel. Remember the point of impact will be an inch or so higher at 10 yards due to the velocity difference. A 9mm barrel may work, but remember the extractor, ejector, and breech are all designed for the larger 40 case, so reliability may suffer.

In doing more research it seems that if you buy a .40 you cn just get .357 and 9 mm barrels. Seems factory barrels will work just fine but there are also storm lake conversions

 

Yep KKM sells conversion from 40S&W to 9mm as well. So I guess it works.

All you need is the barrel as said if you own a .40. That and mags. The 357 & 40 share the same mags.

More interested in the 9mm conversion from .40. So just barrel and mags. Seems easy enough

Picking up the pro in 40 this week.

More interested in the 9mm conversion from .40. So just barrel and mags. Seems easy enough

 

I'm nor intimate with the M&P line but just a heads up. Because of differences in case diameter be cautous of the extractor and ejector locations when using a conversion barrel.

the frame is the same for the 9mm and .40 so YES you can swap the slide and barrel. and if you have a .40 you just need a 9mm barrel and mags, but you can't use .40 in a 9mm slide.