I have two or three different manufacturers versions in 5/30 but none worked well consistently. The springs would get jammed by the rivet if they were drilled through the back spine.
The LAR style mags actually work better I have found. I also use magwedges so that they are all tall enough to fit in normal pouches.
I have tried grinding the lip, the edges and even flipping the spring on several and tried tracking what worked best. In the end, it didn't seem like anything mattered. Some mags work and some don't.
I can send you mfr names and images of the modifications this weekend if you pm me.
I can't even recall offhand the company names atm lol. sorry
