[10-Ring]

I have started contemplating another 10mm pistol, specifically the Glock 20. What I'm wondering is it a simple barrel swap if I want to shoot 357sig from it? What mags would work?

[James Bondrock]

This does not seem feasible to me. The problem would not be in the barrel, IMO, but in the magazine. The 10mm and .45 ACP for which the G20 and G21 were designed are longer cartridges (in overall length) than the .357 SIG, which requires a deeper (from front to back) magazine, the reason these guns' grips are so big. I don't see how the shorter (and bottlenecked) cartridge is going to feed out of the deeper magazine.

[only1asterisk]

People have done it, but James is right about them not feeding too well.

David

[Rich357]

If you bought a "short" 10mm (.40S&W) the switch can be as simple as a barrel change.

If someone would neck down a 10mm to handle a .355" bullet (maybe it has already been done?), then a barrel swap may work well.

Rich

[DamnedDirtyApe]

Regular .40 S&W shoots just fine from a stock G20 with a stock 10mm mag -I do it often, and even reload some 40's for this purpose to shoot from my G20.

.357 SIG is a necked down .40 case. They fit just fine in a stock G20 magazine.

All you need is a .357 SIG barrel, available from Barsto, Jarvis, KKM.

KKM drops right in, without any fitting involved. Barsto or Jarvis might require shipping the gun to the factory for some adjustment.

[Black Snowman]

I don't know about necking a 10mm down to .355 but I do know they necked one down to .224, the infamous .224 BOZ cartridge. I've always thought a 10mm necked down to .355 could be cool too :)

[agtman]

Yep, DDA is right.

You should check out the 10Ring over on GlockTalk, where there have been a ton of posts about the G20 (& 29's) barrel-swapping versatility to shoot .40S&W and .357Sig.

A number of people have posted about shooting .357Sig from their 20 using an aftermarket drop-in barrel (e.g., Fed. Arms, KKM, Bar-Sto, Jarvis). I don't recall any complaints about the .357Sig giving feeding problems from the 10mm hi-caps (preban 15rd mags).

Rich357: a 10mm case necked down to .355/9mm is a 9x25 Dillon. There's been some talk on the 10Ring about a group purchase of BarSto 9x25 barrels that would fit the Glock 20.

That would then make the G20 a 4-caliber shooter, with only a 10-second barrel needed to change calibers: 10mm AUTO, 40S&W, 357Sig and 9x25 Dillon.

HTH. :)

[Black Snowman]

Oooh, 9x25 Dillon. Thanks for the info. I'm shopping for powerful auto-loaders right now and was set on the 10mm, now I'm not so sure. Might go .38 Super or some other wierdness. Now that I know about the 9x25 Dillon I'll have to check it out :D

[10-Ring]

Yeah, I tried a straight swap w/ a 20 & a 30-something (fullsize Glock in 357sig). Barrel was no problem but the mag was a concern.

[MCNETT]

.357sig, .40SW, and 9X25 all run perfectly through my G20's magazines. A bbl swap is all you need to do.
-Mike

[only1asterisk]

I have a friend that has a Glock 20/357 sig. His will fail to feed about once every 2 magazines. Are there any tricks to getting them to feed? Do certain mags work better than others? I'd sure like to know before he rechambers the barrel and I start to supply all the ammo for it.


David

[C. H. Luke]

"... What I'm wondering is it a simple barrel swap if I want to shoot 357sig from it? What mags would work?"

Have a G20 with a KKM .40 bbl. in it.

Using the normal 10 mm fact hicap mags have had zero problems with it.
Shoot handloads using slightly longer OAL but not the extreme that 1911's
sometimes requir in OAL.