All glock .40’s can convert to .357 sig with a barrel swap. I have a glock 27 in .357 sig on my waist right now. I would think that most 40’s could easily convert to .357 sig. And maybe even 9mm as well.
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The one caveat to that is you can not currently swap the barrel of a Glock 23 Gen 5. Glock has not put out a Gen 5 G32, and there are differences in the barrels between Gen 4 and Gen 5.
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Lots of the Glocks are interchangable but be careful! Especially magazines some don’t will at all. My 40 cal works well with 9 mm barrel and stock mag, but I carry with 9mm mag.
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I know it’s been a while since this thread has been going but the only conversion I have done was from 10mm to 40 S&W in my Gen 4 G20.
Conversions can only go down and not up??
Reason I ask is the G20 and 21 are basically the same frames and slides, the 21 mags fit in the 20. Is it the barrel diameter that would be the issue, The breach faces two different sizes, different extractors? Wishful thinking if the G20 could shoot 10, 40, and 45 I am guessing.
Curious if anyone has any info they can throw my way.
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I don’t know what caliber what model is without looking them up. 9mm, 40 and 355 sig all have similar rim diameters for the extractor to reach and grab.
Assuming the hole in the slide is large enough for the caliber barrel you desire, the question is weather the extractor will have enough travel for either cartridge. One could possibly machine it deeper to reach the smaller cartridge. Then a custom extractor with more offset might be needed for the larger rim. I believe it could be done, but it would be easier and cheaper if someone else has done it before and sells all the needed parts.
Lastly the ejector is a consideration but they are easy enough to change on a Glock.
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In the SIG world, how they have chosen to accommodate 9mm, 40S&W, and 357SIG is thus: 40 and 357 are based upon the 10mm cartridge, different barrels are required, and the common breach and extractor suffice. 9mm is not only a different barrel and recoil spring, but it is also a completely different slide assembly. (I am personally shy of up-leveling an older manufactured 9mm P239 to 40/357 but have no qualms using a manufactured 40 or 357 (P226(357) or P229(40)) in any of the three configurations.) The bottom line always is to consult the manufacturer for any changes to the “as-sold” product.
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