I have a couple of 3rd gen pistols (3906 and 5906). As in a year my diplomatic mission will termitate and I'd bring them in Italy I need to rechamber their barrel to the silly 9x21, not being legal the 9mm Parabellum (9x19) in that Country. Can anyone refer me to a gunsmith that usually does that kind of job? BTW, I have been living in Miami.
Thanks for any advice...

Have you asked S&W customer service if they will do it and keep the warranty valid?

Yes, I did. They can't do it.
Actually that's quite weird as they chamber in cal 9x21 every single handgun originally produced in 9x19 that S&W exports to Italy; a good deal...

I think what you should have written is: "They wouldn't do it." I'm certain they can do it. Pretty simple machine operation to increase (slightly) the depth of the chamber. Re marking the pistols might actually be a bigger problem . . . I can understand them not wanting to do this.

Is the 9X19 ammo illegal or the ammo AND the pistols?

Can you get a custom barrel from an aftermarket vendor? If it were me, and I was coming back at some point, I would not want to permanently alter the barrel. The Super 9 which was built on the 5906 frame had a 9x21 barrel in the set, but it has a 5" slide.

The key in your question was that you asked about altering a factory part. Try asking the Performance Center-or maybe the parts folks- about buying a new 9x21 mm barrel or 2.

If that doesn't pan out, you might try Wayne Novak about rechambering/marking. Would be minimal work to rechamber. If you want to keep the warranty, buy spare barrels for the rechambering and if there are issues, stick the stock barrels back in before returning them to the factory. OR- if you're going to be in Italy for an extended period, see if there's anywhere in Italy where you can get the barrels.

I sold a 6906 barrel cut for 9x21 to a forum member not long ago. I departed Italy in 1998 and had no need for it any more. Italian laws also don't permit the use of hollow point ammunition for self-defense but you can use it for target practice. Buona fortuna.

Thank you guys for your concern. In Italy is considered illegal owning and importing semi auto handgun in 9x19, but the caliber itself is allowed and revolver chambered for it as well. The problem is that I have to import my guns already modified, as the official importers do. After importing, I have to have my guns proof marked in Italy. I also own a 5606 with a long slide purchased at Numrich and a 5" barrel that a member of this forum sold me about a year ago for which I haven't such a problem.
I asked Performce Centre of S&W to rechamber my barrels, talking to the same guy whom I contacted in order to have my long slide fitted with extractor, barrel bushing, firing pin, safety lever and so on.
By the way in that occasion, in order to have the best matching possible between barrel and bushing I sent to S&W both the slide and the barrel in 9x21. Actually to be legal the barrel marked as "9mm" requires to read 9mmX21" a very simple adding... I agree S&W absolutely COULD rechamber the two barrels, but prefers not to do it. My only, pratical option is to find out some gunsmith that usually does rechambering jobs...

I'm surprised that S&W doesn't have replacment barrels in 9x21 for your gun. As you say they do export such guns, the only other thing would be the barrel hood width. I have a early 3900/5900 9x19 barrel with the narrow .265" hood like new for $60 if it would help you out.

The problem is finding Simeone who can ream 2mm deeper a couple o barrel chambered for cal 19x21... I've already got them. If I just were allowed to bring them to Italy, I wouldn't have any problem in having my barrels being cut 2mm deeper. I didn't think it should have been so difficult in USA, otherwise a heaven for a gun fan lime me!

I don't know who would do it. I ordered a barrel from a well known barrel maker who made me one in 9X21 for my 39-2. Over the years, I traded away the original 9mm barrel which was a big mistake. I wish I could locate an OEM barrel in 9X19, so I did not have to handload always.
Russ

PS
The barrel maker no longer offers barrels other than 1911.

The problem is finding someone who can ream 2mm deeper a couple o barrel chambered for cal 19x21... I've already got them. If I just were allowed to bring them to Italy, I wouldn't have any problem in having my barrels being cut 2mm deeper. I didn't think it should have been so difficult in USA, otherwise a heaven for a gun fan like me!

Did you call Bar-sto? They make them for NCIS's Sig 228s, and they are basically factory barrels re-cut.

Call either the PC, Wayne Novak or BarSto. If they won't/can't do it they'll likely point you to someone who will.

If you had some 9x21 ammo, any good gunsmith with a 9mm reamer could do the job with no problem. Re-marking the caliber might be a different story.

A 9mm Parabellum and a 9x21 have the same case diameter just forward of the extractor groove. I couldn't find reamer dimensions, but both are also tapered cases. Going 2 mm (roughly 0.008") deeper with a 9mm Parabellum reamer might result in an oversize chamber and bulged brass.

Several of us have mentioned Wayne Novak. Check his website and give them a call. They're very helpful folks.

Exellent remark WR Moore! A 9 parabellum chamber is for a case 19.15 mm (0.754 in) in length, 9.93 mm (0.391 in) base diameter and 9.65 mm (0.380 in) neck diameter vs, 9x21 that has a case 21.15 mm (0.833 in) in length, the same 9.93 mm (0.391 in) base diameter AND 9.63 mm (0.379 in) neck diameter. Going 2mm deeper with a 9 para reamer might result in a slightly oversize chamber for a virtual case with a neck diameter of 0.380" (instead of 0.379") and, probably a base diameter of 0.393". Considering the normal mechanical allowance and play between chamber and cartridge, I don't know if I'd have bulged brass...
In Italy I usually handload 9x21 with dies made for 9mm para.
I'll try to call Wayne Novak , anyhow.
I thank all of you for your advices.