My experience putting somewhere north of 1500 rounds through these magazines:
- The magazine springs are not creep resistant. What does this mean? Well, OEM Glock magazine springs are highly creep resistant. If you leave them loaded for a long time, they will not lose hardly any length or strength. I believe that the OEM springs are made from 17-7 PH stainless, but it's just as likely that it's Glock's own secret blend of 11 herbs and spices. The Shield (Checkmate) magazine springs on the other hand, hoo boy. They seem to be made of chrome silicon or music wire. The standard spring is already on the short side, and after being loaded for just two months it will get so short that the feed pressure on the last round dropped 55%. Lest you say that's normal - they now have about half of the last round feed pressure that an OEM 10rd magazine spring puts on the last round out of the mag. This is Not Gud™ and will result in malfunctions that will creep up on you.
- The +10% seems made of the same stuff as the standard spring. When fresh, it has significantly more feed pressure on the last round than an OEM magazine. After being left fully loaded just two months, that drops to about 96% of the OEM feed pressure. Serviceable enough.
- Fresh out of the wrapper, the standard magazine springs will probably feed most hollowpoints just fine. After being loaded two months or more, you'll start to see a lot of nosedive FTF's.
- The +10% magazine springs feed the hollowpoints that I've used just fine. I've put about 200 each of PPU PPD92 147gr and Win Ranger RA9SXT through a mag with a +10% (that had been left loaded for five months) without incident.
- Even with the +10% magazine springs, certain rounds don't mix well. For example, I have a ton of Freedom Munitions on hand. Works great out of my other Glock setups. But out of the S15 with +10%, I get nosedive jams. I attribute this partially to the magazine design and partially to the bullet design. The magazine presents rounds with less nose-up attitude than OEM magazines do, and the gap between the top of the magazine and the bottom of the feed ramp is larger with the S15 magazines. Additionally, the bullets used in FM ammo are plated, not jacketed. They're very soft, so when they catch on something they dig into it. This all seems to be a recipe for nosedive FTF's where the tip of the bullet is jammed under the feedramp, hard.
- Shooting jacketed round nose ammo however, I haven't had a single malfunction with the +10% spring in about 800 rounds.
- G43X/G48 10rd OEM magazine springs seem to fit and work in the S15 magazine. I haven't tested this combo much at all, but a buddy of mine has had good results with it.
Hopefully I can put a video out about all of this sometime soon.
Ran another 250 rounds through my S15 mags tonight. 200 147gr Lawman amd 50 147gr Gold Dots. Still no issues. Up to 1050 rounds through 5 mags.
Shield is making a "Gen 2" S15 mag:
"The victor is not victorious if the vanquished does not consider himself so."
― Ennius
Shield S15 mags GEN 2 update
This comes from Brandon an employee at Shield. If you want to see that original post you can find it on the "Shield Wall" Facebook group.
What's different with gen 2? Two major differences: they are now ambi, and have a more corrosion resistant coating called Everlube. Other finish options will be available soon. There are some other minor changes like the follower, which has been changed to help REDUCE the Glock mag rattle. We also brought the overall width in a few thousandths to help them drop free in tight frames. Spring, locking plate, base plates, extensions, and steel mag catches are backwards/forwards compatible gen 1 to gen 2.
When will combos be available? ASAP. We are going to try and have enough mag catches to put the catch combos in stock soon, the rest of the combos will follow as we can.
There are a few people who backordered an S15 Gen 1 mag before we turned it off (whoops), so if you don't have a shipping notification, then you're getting a gen 2. You'll get a shipping notification around or at the same time they go in stock.
Wow what timing. I was literally perusing this exact thread last night to get an idea of how these S15s were faring in actual use...
Placed an order for two gen 2 mags and a steel mag catch direct from Shield last night at 5pm mountain time. Demand was quite high, there was a number of drop outs of the web site during the process, which took a couple hours off and on. They are no longer in stock, but available to back-order now apparently.
Will report back after testing in my G48.