I went through a lot of Cproducts Grendel mags back in the earlier days and they were all over the map for dimensions. I had to bend feed lips on some of them and even smash bodies smaller with clamps for some of them that were bowed out so far that the tail of the spring would slip out between the mag body and the floor plate.
The main problems as best that I could guess from looking at them--- They were stamped out correctly (good dies), but the jigs were off/sloppily adjusted for welding. Some were wider at the front and some were wider at the back. Warpage during heat treat seemed to be an issue as well. The only thing to do was bend them until they worked, or return them as LRRPF52 said. I hate shipping stuff, so I bent all of mine.
Quality seemed to go up on average over time, and some folks had zero issues while others got bad ones. The last batch that I bought had no apparent issues at all with the 25 rounders, and the 17 rounders were pretty crappy. My best luck out of the bag was always with the 10 rounders. I haven't bought any mags over the last four years or so, so I couldn't say how much has changed. I have noted that far less complaints have surfaced lately though.
One thing I will say about the spring steel that they use--- They are pretty darn durable once you get them working right. My buddy ran over a loaded 25 rounder in his gravel road (dropped off the 4wheeler earlier) with a Ford sport trac and it held up well.LOL Some rounds had popped out and it was scarred up but it still functions fine to this day. To get the ones that I had that were bulged bent enough, I had to take a large padded clamp and squeeze the sidewalls until they were touching each other. They typically just spring back. You really have to squeeze them to get them bent!
The main problems as best that I could guess from looking at them--- They were stamped out correctly (good dies), but the jigs were off/sloppily adjusted for welding. Some were wider at the front and some were wider at the back. Warpage during heat treat seemed to be an issue as well. The only thing to do was bend them until they worked, or return them as LRRPF52 said. I hate shipping stuff, so I bent all of mine.
Quality seemed to go up on average over time, and some folks had zero issues while others got bad ones. The last batch that I bought had no apparent issues at all with the 25 rounders, and the 17 rounders were pretty crappy. My best luck out of the bag was always with the 10 rounders. I haven't bought any mags over the last four years or so, so I couldn't say how much has changed. I have noted that far less complaints have surfaced lately though.
One thing I will say about the spring steel that they use--- They are pretty darn durable once you get them working right. My buddy ran over a loaded 25 rounder in his gravel road (dropped off the 4wheeler earlier) with a Ford sport trac and it held up well.LOL Some rounds had popped out and it was scarred up but it still functions fine to this day. To get the ones that I had that were bulged bent enough, I had to take a large padded clamp and squeeze the sidewalls until they were touching each other. They typically just spring back. You really have to squeeze them to get them bent!