Glock 21 to 10mm
- Thread starter stevek
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newfalguy101
Member
Will a 10MM mag even fit the mag well??
Guess what the difference in SAAMI max length for 10mm and 45ACP is.
JR24
Member
My understanding is something like this is all you really need.
https://www.opticsplanet.com/stormlake-34017-glock-21-21sf-10mm-conversion-for-45acp-4-6-ss.html
But the consensus on Glock talk is for absolute reliability you'll want to swap out the extractor for a G20, and possibly a new recoil spring.
I'd recommend searching Glocktalk.com, I recall there being some big threads on converting the 21 and 30 to 10mm.
https://www.opticsplanet.com/stormlake-34017-glock-21-21sf-10mm-conversion-for-45acp-4-6-ss.html
But the consensus on Glock talk is for absolute reliability you'll want to swap out the extractor for a G20, and possibly a new recoil spring.
I'd recommend searching Glocktalk.com, I recall there being some big threads on converting the 21 and 30 to 10mm.
The magazines are identical in external dimensions, because the frame (and in particular the mag well) are identical.
Dave
newfalguy101
Member
Soooooooo what you are saying, without saying is the frames are the same??
JR24
Member
Yep, same frame
I’m not a glock guy, so I don’t know for sure. But 10mm and 45 act double stack mags are often dimensionally the same externally, or the same up to the feed lips. People often assume the 10mm is longer. Nah, the 45 is just so fat it looks shorter than it is.
JR24
Member
Not Glock related, but my 10mm RIA 1911 runs fine with Wilson .45 ACP mags.
MTMilitiaman
Member
The frame is the same and G20 mags will work in a G21 frame.
The factory recoil spring assemblies are the same, 17 lbs, but it is common for G20 owners to run heavier springs. I am running a 20 lbs ISMI in my Gen III G20. Not uncommon to see 22 or even 24 lbs springs.
The main difference in slide dimensions. The .45 ACP runs at 21000 PSI, 23000 for +P. The 10mm is running at 37500 PSI. So while the exterior dimensions are the same, the G20 slide is thicker internally, and more beefy.
You would need a new barrel and almost certainly a new recoil assembly. If people run 20 to 24 pound springs with the heavier slide of the G20, I would think one would be mandatory for proper function with lighter slide of G21. I believe over at GlockTalk they also recommend G20 ejector. This will require detail stripping the frame, but this isn't a big deal with the Glock.
The factory recoil spring assemblies are the same, 17 lbs, but it is common for G20 owners to run heavier springs. I am running a 20 lbs ISMI in my Gen III G20. Not uncommon to see 22 or even 24 lbs springs.
The main difference in slide dimensions. The .45 ACP runs at 21000 PSI, 23000 for +P. The 10mm is running at 37500 PSI. So while the exterior dimensions are the same, the G20 slide is thicker internally, and more beefy.
You would need a new barrel and almost certainly a new recoil assembly. If people run 20 to 24 pound springs with the heavier slide of the G20, I would think one would be mandatory for proper function with lighter slide of G21. I believe over at GlockTalk they also recommend G20 ejector. This will require detail stripping the frame, but this isn't a big deal with the Glock.
Ohen Cepel
Member
I would get a G20 upper to keep it simple. However, that may cost as much as a used G20.
I kind of agree. Can the 21 be converted? Sure. However, for the effort, it would make more sense (for me personally) to just buy a 20 and be done with it. I would guess there is a decent market of lightly used 20s that were purchased for some sort of northerly one-off trip for big predator defense and quickly dumped once they got back when the purchaser figures out how doggone big the 20 is.
I have to admit, despite having not-huge hands, the 20 has tempted me for some time. I think the next Glock I buy is going to be a 30 to go with the 21 mag I found in my trunk-o-magazines or a full size 20. I had a 21 and liked it. I traded it toward a 1911 which I also liked, but the full size big bore Glocks are real purpose driven workhorses.
I have to admit, despite having not-huge hands, the 20 has tempted me for some time. I think the next Glock I buy is going to be a 30 to go with the 21 mag I found in my trunk-o-magazines or a full size 20. I had a 21 and liked it. I traded it toward a 1911 which I also liked, but the full size big bore Glocks are real purpose driven workhorses.
TTv2
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That's what I was planning on doing years ago, but a complete 10mm upper costs near as much as a new Glock... $450.
https://www.gunbroker.com/item/811932164
I've since decided a Glock 40 MOS and a factory threaded barreled S&W or Walther .45 is the better way to go. OP, swapping uppers isn't that great an option and I don't believe that a simple barrel drop in is okay with 10mm and .45. I know it works fine for 9mm and .40, but 10mm and .45 are two very different cartridges.
I'm looking to convert a Glock 30SF, my understanding from talking to several Glock armorers is that in a vast majority of cases all you need is the BBL and mags. Supposedly the seating in the 10mm chambers is such that the .45 extractor will work. A few people due change the springs but I talked to a few Glock Armorers who said that wasn't necessary. The only thing I'm concerned about is I have a custom creations slide on my 30SF and I'm not sure about fit issues. On the other hand it's substantially beefier then the stock slide.
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