Since you popped the cherry on this one, I can chime in. I was sworn to secrecy on the gen 2 mags. There are some minor geometric changes coming on the gen 2's as well as ambi capability.
Wait... But aren't Glocks supposed to be perfect out of the box?
Since I changed to the SA metal mag catch the S15's have functioned flawlessly. And to be fair, the OEM mags, prior to totally switching the the S15's had just as many failures to feed, although different circumstances. With the first 300 rounds or so, still with the plastic OEM mag catch, I suffered 3 failures, one being my fault, being limp wristed and using the slide stop to release the slide. The other two were rounds with the shoulder of thick and protruding brass shells that got hung up. My defensive ammo's shell casings are much sleeker and less likely to catch on anything. The S15's did wear down the plastic catch quickly, but until that time there were very few issues.
I have since replaced the plastic catch with the SA catch and haven't had a single feed or function issue with a few hundred more rounds of the same practice ammo.
I know some folks are going to slam me for what I did upon observing the beginning of some scratching in the magwell but I'm going to share it anyway. For observational purposes only. Any modifications you make is solely at your own risk. I recognized that two things were going on: 1) I don't tend to put the mags straight into the well, but with the nose touching first ,then bringing the back portion of the mag into the well before slamming home. Perhaps I need to work on my reload technique, and will try to be aware of what I was doing. 2) The corresponding area of the magwell that started to scratch were fairly definitive in showing that the two upper corners of the mag were the culprits.
If I have any general criticism of these mags and Shield Arms is that the manufacture lacks the refinement of addressing the corners and edges of these mags. I have one friend that cut his finger on one of the sharp front corners of a S15 while loading rounds before doing what I did with my mags. I took note of the front corners and "dehorned" them almost immediately after getting them. FWIW I set up and refine guitars as part of a hobby, and doing something like this is not a whole lot different than addressing "fret sprout" on a guitar. It is about just smoothing things out so they don't catch on things. I did not address the rear of the mags which is where the magwell scratching is occurring.
Before doing so I noticed that as I ran my hand over that area with rounds in the mag, I could feel the corners, but didn't see that the external areas contributed to round retention in any way. So I simply dehorned those corners as well. Now when I run my finger over that areas I feel nothing sharp or jagged. While I may not have corrected 100% of the scratching problem I would like to believe that I got 90%. I didn't touch the area down by where the primer sits, but may after once again studying where the scratching is occuring in the magwell. I've polished out the area with 500 up to 1200 grit sand paper so I will be able to identify future scratching damage. I cycled rounds through both mags manually and found no issues in chambering, even when once or twice I didn't fully rack the slide back or let it slam forward without impeding it a bit.
The one thing, besides round capacity, that I like about the S15's vs the OEM's is the smoothness which with they eject from the magwell upon reloads. It stands to reason as the OEM's plastic casing is textured a bit and while minimial does have some drag. Certainly S15's aren't for everyone. I'm anxious to see what Shield Arms comes up with in their gen 2 revisions.
Edit: I want to share a photo of the practice rounds that I've been using that depicts the brass shoulder that caused all three of the S15 failures to feed over hundreds of rounds noting ZERO FAILURES AFTER INSTALLING THE METAL CATCH. My Federal HST defensive ammo's shoulder protrudes much less and while I've shot fewer of those (@ $2/rd) there have been no issues with those either.
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