Glock 20 Mag ?

[Johnch]

I am about done making a bolt action 9 mm carbine that uses Glock mags
I just need to do the finish work on the stock
As I wanted a simple plinking carbine

But I had a thought ( Dangerous sometimes )
As I am going to start in the next week or 2 on a semi auto 9 mm carbine that also uses Glock Mags

Could I load some 9 mm ammo with heaver bullets ?
And as I was thinking about heaver bullets
I had the idea of loading the rounds to a longer OAL , like 1.250" instead of the 1.65" ( about )
Using the longer 9 mm ammo in a Glock 20 mag instead of the Glock 17 or Glock 22 mags I will be using in the bolt action 9 mm carbine


My question is
Are Glock 17 and Glock 20 mag catches in the same place on the mag ?
As I had the thought if the mag catch location is in the same place
I could make add thin shim in the back of the mag well to move the Glock 17 mag forward so the mag catch would work
But be able to remove it when I wanted to use heaver bullets in a Glock 20 mag

Your thoughts
John

[bryan scott]

Holding the mags up against each other they appear to be the same ...the mag catch distance from top that is.

[Johnch]

Thanks

John

[BK7saum]

The glock 20/21 mags are both wider and longer front to back, I believe.

[BK7saum]

You would need to shim the back and the sides. Maybe a later or two of LDPE plastic (milk jug) or other source would get you the desired spacer width.

[Idaho45guy]

The glock 20/21 mags are both wider and longer front to back, I believe.

Yeah, no way a G20 mag will work in a magwell designed for the G17 mags. It's too fat fore and aft.

[Sig556r]

Won't work, 10mm Glock mags are bigger

[BK7saum]

But the way I read this, He has a 10mm carbine and wants to switch over a 9mm barrel/bolt. Could be wrong, but seems like he already does have a 10mm lower/action. He wants to use 17 mags for normal 9mm loads in the 10mm lower and heavier, longer 9mm loads in a 10mm magazine.

[trebor44]

First issue is as been pointed out: size of the mags differ. Second issue: feed lips of the G20 mag versus the G17. Why not just shoot 40 S&W if it is 10mm?

[trebor44]

First issue is as been pointed out: size of the mags differ. Second issue: width of feed lips of the G20 mag versus the G17. Why not just shoot 40 S&W if it is 10mm?

[kerplode]

Magwell dimensions and shimming issues aside, I think you're going to find that 9mm won't feed reliably through the G20 mag. The internal geometry, feed lip geometry, and follower of the 10mm mag are all designed for a fatter, longer case -> The 9mm isn't going to stack correctly and will likely bind up in the neck area where the stack transitions from double to single feed.

If you're just building a plinker then maybe it's NBD, but for a serious weapon, it's a no-go.

[Johnch]

Darn
But thanks

I am planning on a 9 mm
I have a Glock 22 and have found the Glock 22 mags work 100% of the time feeding 9 mm ammo

So my thought was just being able to feed a 9 mm round that I loaded to a longer OAL
As I sometimes plan on shooting 158 or 160 gr sub sonic 9 mm ammo with a Suppressor

Thanks
John

[kerplode]

I'm not sure you can use bolt-action feed reliability as a predictor for reliability in a semi-auto. The dynamics and timing are just too different.

I suppose you don't have much to lose in trying except the cost of the mag(s) and your time. It's interesting to find out new things, but at the end of the day, what will an extra-long 160gr subsonic do that a mag-length 147gr subsonic can't? Is that worth solving all the problems this will entail, and making the rifle be forever awkward to use with the correct mags if the G20 thing doesn't pan out?

Just tossing out another perspective here, don't let me discourage you from trying it if you think it has merit...