The rail is about .25" higher than an AR rail, so if you replace the stock, you may want a riser. I use one (not pictured). I found the right side safety selector digs into my hand. I've reversed it 180 degrees (as seen) and it's no longer an issue. I added a magwell and compensator. I've actually never shot it without the comp so not sure how much it helps. I would have gotten the large brake (from AT) but heard it messes with shot pattern. It's also heavy, and not sure I wanted a huge weight hanging off the end of the barrel.
It takes some break in to get it to cycle lower velocity rounds. After though, it cycles just fine with regular 1200 fps Federal bulk.
I have a 19, and some 12 and 10 round magazines. The 19 does quite function 100%. Occasionally a shell must catch, deforming the end enough to not chamber. I wonder if some higher quality shells would fix this. But it's not all the time. The magazine shown is a 12 rounder, which is a 9-rounder body with a Taylor Freelance extension. Without the extension, if you cut down the magazine spring guide, it will now hold 10. All my 10 and 12 rounders seem to function 100%. I attached belt clips to the magazines from dissident arms.
The magazines do have a bolt hold tab. This is apart of the follower and sticks out a cutout in the top of the magazine when empty. This causes empty magazines to not drop free (as it pushes against the inside of the magazine well when empty. It can however be removed/disabled. Doing so will allow empty magazines to drop free but not lock the bolt back. So it's a trade off. I will say however, with the 19-round magazine, because of the curve, if you don't remove/disable the tab, it likes to prevent the follower from moving freely and can hang up, causing it to not feed the next round. Once removed, I no longer had that issue.
The gun came with two 5 round magazines. One of the two I got, the body was so out of spec it wouldn't even fit in the magwell. After sanding down the outside I could sort of fight it in. No matter, it wouldn't feed. I took it apart and kept the follower and base pad as spares.
With the Holosun 510c on it, man, is it easy to shoot.