I have a 2 point adjustable sling (made by me) attached on the left hand side at the front and the right side at the rear with the quick disconnect. I put a mag tub mounted pic rail for a standard light (stream light w/2x AA batteries and a tail switch).
I'd show a picture but I can't yet. Hey I was wondering, does your magazine cap ratchet and lock in place? Mine didn't but I machined some material away and it works as it should now. The feed ramp was a little rough so I carefully worked at it too.
If you are thinking about an S&J Hardware bolt release bar they need a little material removed from the fore stock to allow room for the tab on the bar.
I've taken mine apart, addressed certain items like the cocking handle, bolt release latch (inside polished mating surfaces). and fire a few hundred rounds of Challenger 71/2 with a few failure to ejects early on. It's due for another tear down and cleaning/lube. It is a new project for me so I have been all over it recently. If you run into something maybe I can help.