MissionaryMike Posted July 25, 2014 Share Posted July 25, 2014 So... I'm looking to build a USPSA Limited gun, and I've found a pretty good deal on a used STI Tactical 5.0. Only problem is that it's a 9mm barrel. I'd like to convert this gun into a .40 s&w using the same upper. I would definitely use the services of a reputable gunsmith. Is this conversion a set and forget/definitely doable, possible w/ some future issues, or a totally don't even think about it scenario? Link to comment Share on other sites More sharing options...
bountyhunter Posted July 26, 2014 Share Posted July 26, 2014 Even if a .40 barrel could be fit into the slide, the 9mm breech face would not be large enough to accommodate the .40SW case diameter. I have a dual caliber 1911 and you have to change the whole top end assembly. Link to comment Share on other sites More sharing options...
RIIID Posted July 26, 2014 Share Posted July 26, 2014 The breech face would have to be opened up, after that the 9mm will not work. Rich Link to comment Share on other sites More sharing options...
MissionaryMike Posted July 26, 2014 Author Share Posted July 26, 2014 It seems like this guy has a competition gun that can run both 9mm and .40s&w barrels in the same slide. Should/could this not be done? Link to comment Share on other sites More sharing options...
bountyhunter Posted July 26, 2014 Share Posted July 26, 2014 (edited) It is theoretically possible to get a single slide to work with both 9mm and .40, but the breech face is cut for 40 size, not 9mm. So you can't start with a 9mm slide and install a 40 barrel. You can start with a .40 slide and install a 9mm CONVERSION barrel in some cases, but it requires a pivoting extractor that can move far enough to hold the smaller 9mm case against the edge of the wider .40 breech face cut. In the case of 1911/2011 using the traditional extractor, I don't think it would extract 9mm properly. Note: I think some of the dual caliber 2011's have replaceable breech faces so the slide can be used for two calibers. I assume it would need a different extractor for each? Edited July 26, 2014 by bountyhunter Link to comment Share on other sites More sharing options...
bountyhunter Posted July 26, 2014 Share Posted July 26, 2014 (edited) It seems like this guy has a competition gun that can run both 9mm and .40s&w barrels in the same slide. Should/could this not be done? This guns slide has had the breech face milled open to .40 size. It is using a 9mm conversion barrel, the outside dimensions fit the slide but it is bored for 9mm. I don't know who sells these (?)It also has a different extractor for each caliber. IMHO, the standard 1911 type extractor would not have enough range of travel to securely extract the narrower 9mm case. Guess how I learned that. Edited July 26, 2014 by bountyhunter Link to comment Share on other sites More sharing options...
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