ETS GEN 2 9mm 32-Round Magazine for Glock Pistols
GLK-18G2
It would be great if there were a set of common & shared firearm industry specs for magazines, like the PC industry has for PCI-Express and PCI video cards, and for common connectors like USB.
Magpul offers a 10-round “competition” mag for glock type pistol with 17-round mag well. The PSA sku is 788767 and as I type this they are on sale for under fourteen bucks each.
“Competition” is the key word you want and it will help you find 10 round magazines for various pistols. Some types of shooting competitions have limits on magazine size. Ten rounds is logical since it’s a nice, even number anyway.
ETS mag quality has been spotty for me. I have two that work fine, a 22 (or is it 23?) and a 40 round one. The 27 round one needed some judicious filing and sanding for it to work. It was tight in the well and wouldn’t drop out at all, and it was jamming up and not feeding when I was testing with snap caps.
Digression: I have twenty snap caps plus some spent brass casings so I can fill even a large magazine without using live ammo. Put the cases in first, then your snap caps. This way you can fill a 40 round magazine for testing without having live ammo in the magazine, and without having to buy more snap caps.
For larger capacity, a Glock 33 round magazine has the metal liner like the stock-capacity ones. Not that much more money to get real Glock quality—unless you need to buy a whole ton of magzines, in which case I can see going to ETS, Magpul, or other cheap brands.