Looking to use a Stern Defense Glock mag well adapter but I want a left side charge handle.
Anyone have any comments on the Stern adapter or who has a side charge BCG/upper that is compatible.

The lrbho lever may need slight tweaking.  On mine it needed a very slight bend to positively contact the lrbho pad on the follower.

The ejector is hardened steel and is not "adjustable" (bendable), so do not try.  If you have ejection problems with your particular combination of parts, you may be out of luck.

I kept getting occasional stovepipe jams when using the adapter,  despite a lot of troubleshooting and using 2 different lowers.

Overall it is a clever bit of engineering.  Lots of people are happy with them, but I eventually got a dedicated Glock mag Spikes lower and I am much happier with the performance. Funny thing; they both cost the same amount.

If you are going to use it in a 5.56 firearm to quick swap with a 9mm upper, make sure you also get an extended length 9mm buffer, at least 5.5 oz., and swap the buffers when you swap the uppers.  9mm uses a much heavier buffer than 5.56. The 9mm bolt is about 0.5" shorter than a 5.56 carrier/bolt; the longer buffer makes up the difference and helps prevent rearward overtravel.

I used one for quite a while, and it ran well.  Tried an Enomag PMag conversion kit and found it ran even better.

I recently got the Stern adapter for glock magazines. I have had zero issues with it so far with about 500 rounds through it. Always locks back.
In regard to the side charger, I went with the Devil Dog Concepts bolt on left side charger. I was somewhat skeptical until I put it on. This is a solid unit and works great without the cost and hole on the side of the upper. I got two uppers from Stern also,  one 9mm and one 40. Both work great. The 9 right out of the box and the 40 after about 100 round break in.
YMMV