Glock 31, 32 and 33 in .357 SIG: A Trade-In Buyer's Guide

Our earlier piece asked whether .357 SIG is still issued. This one assumes you want the cartridge anyway and sorts out the three Glock frames.

One cartridge, three frames

The Glock .357 SIG family is easy to remember once you see the pattern. Each model uses the same frame as a .40 S&W sibling, which means similar grip dimensions, similar controls and, in many cases, similar holster fit. The differences are in the barrel, the chamber and what the slide is marked for.

The G31 gets text only in this guide. Read the manufacturer's information and check current listings yourself before you shop for one.

If your first question is whether the cartridge is still a good duty choice, our article on whether .357 SIG is still issued covers that. This guide assumes you have a reason to want one, whether that is collecting, range use, or an agency issue.

Which frame for which job

The G31, the full-size one

The G31 is the duty-sized member of the family. It shares its frame with the G22, so a hand that is comfortable with the .40 gun will find it identical. This is the model for anyone who wants a belt-worn pistol and values grip length and capacity over concealment. If you also own or are looking at a G22, the parts and accessory overlap is part of the draw, and our Glock 22 Gen5 review covers the platform.

The G32, the compact one

The Glock 32 Gen4 is the compromise frame. The listing shows 13+1. This is the size class that does the most jobs: a belt pistol for officers who prefer a shorter grip, a plainclothes gun, and a practical range pistol. If you want one .357 SIG to cover everything, the compact is where most people land.

The G33, the subcompact one

The Glock 33 Gen4 is the small one. At 9+1 per the listing, it is a backup or off-duty pistol rather than a primary. Subcompacts of any caliber are more demanding to shoot than larger frames, and a high-intensity cartridge in a small gun makes that more obvious. Think of the G33 as a specialist tool: a second gun that shares its ammunition with a larger .357 SIG pistol, if you own one.

Barrel swaps: what is and is not simple

The shared-frame idea leads people to a tempting question: can I just put a .357 SIG barrel in my .40? The conversation around this is widespread, because both cartridges use the same case head and the same magazines, and swapping a barrel is how many owners test the cartridge.

Treat that as background, not as a recommendation.

• Whether a given gun accepts a given barrel depends on the model and generation. Ask Glock or a qualified armorer.
• A duty gun is covered by agency policy. Changing a barrel may void agency approval or warranty.
• Aftermarket conversions in the other direction, such as 9mm barrels for .40 or .357 SIG pistols, are a separate topic with their own compatibility and reliability questions.

A barrel swap that you do not fully understand is not a shortcut worth taking on a duty gun. If you want a 9mm, buy one; our Glock 17 vs 19 comparison shows where to start.

Buying a used or trade-in pistol

Agencies that move off a cartridge send guns to the used market, which is why trade-ins exist at all. The upside is that many agency guns have been maintained to a schedule and carry modest round counts from qualification. The risk is that "modest" is a story, not a number, and holster wear, dropped-gun history and aftermarket parts do not show up in a product photograph.

A checklist worth carrying to the counter:

1. Frame and finish. Look for holster wear, rail wear, cracks near the pin holes, and corrosion in hard-to-see places.
2. Barrel and chamber. Look for pitting, bulges or tool marks. Have a qualified person inspect the chamber.
3. Slide and springs. Check slide fit, and ask whether recoil springs have been replaced. A duty gun that has never had its springs changed is overdue.
4. Triggers and internals. Aftermarket parts may be fine or may be a problem; ask.
5. Magazines. Count them and inspect each. Magazines wear, and a used gun with tired magazines will not feed well.
6. Documentation. Ask for any service or armorer records, and check that serial numbers match.
7. Legal. Transfers go through a licensed dealer, and you are responsible for federal, state and local rules.

If anything on that list is a problem, factor the cost of fixing it into the decision before you commit.

Ammunition reality

.357 SIG ammunition is produced by major makers but has a smaller market than 9mm, so range and defensive loads are less plentiful. Plan for fewer choices and make sure your duty load is something your agency approves. Our duty ammo tier list compares the loads agencies commonly look at.

Pick by role

Bottom line

The Glock .357 SIG trio is neat, easy to understand and well supported by Glock's parts system. The cartridge makes sense for people who know why they want it. For everyone else, the practical answer is the 9mm, and the useful part of this guide is the inspection checklist and the plain description of the three frames.

Confirm exact capacities, dimensions and compatibility on Glock's own materials before you buy, and have an armorer look at any used gun.

Editorial note: This is an independent editorial overview built from manufacturer specifications and publicly available information. We have not performed hands-on testing of the products discussed, and nothing here is a performance guarantee. Verify specifications, compatibility and legality for your own situation.

Affiliate disclosure: Some links on this page are affiliate links to Ammunition Depot. We may earn a commission if you buy through them, at no extra cost to you. Our editorial choices are not influenced by commissions. Check current price, stock and specifications directly with the retailer.