glock 27 to 357 sig conversion

[spreezeye]

I'm wanting to convert my 27 to 357 sig. I know some (sigs) have mags that say 40/357.
is there any issue with the magazines or feeing at all that anyone has run into?
thanks

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[Medic!]

My 23 and 35 with .357 Sig barrels use there original 40 mags. No problems.

The barrel and 357 marking on the magazine are the only things changed that I can see.

 

[spreezeye]

My 23 and 35 with .357 Sig barrels use there original 40 mags. No problems.

The barrel and 357 marking on the magazine are the only things changed that I can see.

Kinda what I thought
Thanks for the info

 

[MrRob96]

I'm not a Glock guy. I've never owned one. A kind of famous Glock guy called hickok45 over in the YouTubes mentions that 40 mags don't work so well for 357sig. Maybe this is old information.

It was in his 357sig vs 40 video I believe.

 

[spreezeye]

I see lone wolf suggests using 357 sig mags

 

[CHLChris]

357 mags and 40 mags (31/22, 32/23, 33/27) are exactly the same. They are interchangeable. In fact, the only change needed is a factory barrel in the other chambering. There's no such thing as a conversion barrel in the way that there are 40-9 conversion barrels. I would ALSO suggest using the other mag, however, but not for function...for your own brain. Since the brass is the same, it would be way too easy to mess up by accident. At least, that mistake would be easy to make if you are running guns in both calibers.

Kind of like there are companies that offer different-colored mags for 300BLK, even though the 300BLK mags are functionally equivalent to 556/223 mags.

 

[Medic!]

OK. My old Glock 357 Sig and 40 S&W followers look the same. Save the markings.
There is some difference in the body however. As the holed in the back of my 40 mags don't line up right when I load 357 sig. For what ever reason it's off buy one round.

They do work perfectly though.

 

[spreezeye]

357 mags and 40 mags (31/22, 32/23, 33/27) are exactly the same. They are interchangeable. In fact, the only change needed is a factory barrel in the other chambering. There's no such thing as a conversion barrel in the way that there are 40-9 conversion barrels. I would ALSO suggest using the other mag, however, but not for function...for your own brain. Since the brass is the same, it would be way too easy to mess up by accident. At least, that mistake would be easy to make if you are running guns in both calibers.

Kind of like there are companies that offer different-colored mags for 300BLK, even though the 300BLK mags are functionally equivalent to 556/223 mags.

Excellent point. I plan on marking the mags

 

[MrRob96]

How is the brass the same? 357 Sig is marginally longer, the brass in the webbing is thicker, and the saami pressures are different. I think this caliber interchangeability is misunderstood. There are synergies between the two rounds but they are hardly duplicates of each other.

A lot of people in this thread say the magazines are exactly the same, yet Glock has different part numbers for them so I'd err on the side of caution. Of course I'm assuming you'll be using these mags for self defense and not range duty.

If it's range duty, then I've been guilty of using 45acp mags with a 10mm p220 myself so I can't say anything. When in matters of my life tho, I'll buy the most reliable mag I can possibly get.

 

[CHLChris]

They are different part numbers only because they have ".40" on some and ".357 Auto" on others.

By "the brass is the same" I just mean that a quick look could easily fool someone...to catastrophic consequences, possibly. I don't mean to say that the brass is interachangeable. I'm just talking about safety for distracted folks (which we all are at some times). Great points, @MrRob96!

 

[spreezeye]

well, got a storm lake barrel, now the time to put it to use!
I'll let you know my results. Haven't decided on which loads to start with
and build a brass stash for reloading purposes. 115's or 125's, I think.

 

[MrRob96]

Good luck reloading this cartridge. I'm having troubles with setting headspace and bullet set back.

I found 124-125gr with a profile set for 357 Sig was the best for eliminating setback.

 

[spreezeye]

It will be a while before reload, you may here from me again, thanks

 

[CHLChris]

The most popular (and historically effective) 357Mag bullet size is 125gr. So I would target that weight for 357Sig since it is designed to be an analog of the magnum version. Makes sense to me...

Oh, and 124 HP bullets are probably mostly designed only for 9mm velocities...

 

[spreezeye]

Good point! I will be looking for the bullets they use in factory loads. I figure they
would be made for the velocity I'm hoping for.
Thanks

 

[MrRob96]

I'm pretty sure the 124gr Speer gold dots will do just fine staying in tact at 357 Sig velocities, or any other jacketed round. I haven't seen any degradation in accuracy with them. I am only plinking. 124 is plentiful and available. 125 is harder to get.

If you're concerned about expansion and bullet performance in gel/flesh, I go for factory SD ammo anyways. Again this cartridge is fiddly to load, for me, and I wouldn't trust my reloads as much as factory stuff.

Just what I've seen from the bit of reloading.

 

[spreezeye]

I'll find one that shoots the best, speed I want, for carry.
Don't need the problems with reloads and all the self defense issues.
Thanks