After having success with swapping in an aftermarket 9mm barrel into a Glock 40S&W, I was wondering if the same could be done with a 3rd Gen S&W. Specifically, could I swap a 5906 barrel and/or slide onto a 4003 with good results? I know the magazines are different, but just curious if the uppers would interchange. I'm guessing not, since I haven't heard about it being done, but you never know unless you ask. Any comments welcome.

I believe that can be made to work only on the TSW models in question.

On TSW models, slides and barrels will interchange between 40 and 9mm models because both use the 40 frame and slide dimensions.

On base (non-TSW) models, the 40 slide will not fit on the 9mm frame because the 40 slide recoil spring tunnel and front rails are too wide.

On base (non-TSW) models, the 9mm slide WILL fit onto the 40 frame (only the rear slide rails will be engaged), however the base of the 9mm barrel (beneath the chamber where it fits into the frame) will need to be narrowed a small but equal amount on each side, then it will fit into the frame, and you will have your 9mm on a 40 frame conversion.

Unless it is a very early 40 frame, the 9mm magazines will fit and function just fine.

One last thing, base model 9mm and 40 barrels will not interchange in each other's slides because the barrel bushings are of a different size (40 is larger).

John

So the 9 and 40 TSW slides are the same? I had noticed the 9TSW barrels seem pretty overbuilt compared to the base 9 barrels, as if they were meant to fill out a 40 slide. If I put a .40 barrel and recoil spring in a 5906TSW does that basically give me an ersatz 4006TSW without any ill effects on the gun itself other than .40 being inherently tougher on the gun?

Yes!

John

I should include the caveat that the 40 TSW barrel is likely to have a slightly wider hood, and may need to be narrowed to fit the 9mm TSW slide.

The barrel bushings are the same on the 9mm and 40 TSW models.

John

Just one more thing, Sir. (I sound like Lt. Columbo... )

The base model 40 barrel will fit into the 59xx/40xx TSW slide, but the barrel camming lugs on the barrel and frame are at different angles, and are therefore incompatible.

John

Hmmm, verrrry interestink! JohnHL, thank you for the insight. I might have to start keeping my eyes open for a good combo. Always nice to have another option these days. I do have a 4006TSWCHP, just not sure I want to mess with it. Thanks again.