Lots of good info.
The jam problem is during extraction. It fires, but then jams; only with 5.56. I can't remember the brand, but it was a big box name.
He doesn't use the gun that often (2 times, maybe, per year) so I'm going to help him clean/lube it first, and try with some other ammo.
The reason I asked about reaming it to Wylde spec's is that I was thinking it was somewhat simple, cost-effective, and may result in better performance.
I'm capable of learning how to do it. I've got over 20k in tools, but they're mostly automotive/motorcycle/home. So I'd need to acquire the specifics required for this job, and then learn the procedure. The hard part is finding the time. A few years ago I decided to pull my Oberheim keyboards out of storage and repair them. I had to buy an oscilloscope, learn IC chip diagnostic procedures, and trace/replace many parts. I did it, but it took months of time.
I love guns, so I may delve. I've been holding off reloading, cuz not sure if I wanna go down that rabbit hole yet, but I keep getting tempted, lol.
This thread overlaps with another I posted several days ago about suggestions for my first yote gun, and I may just break down and build my first AR.
I'd really like to get either a Rainier or WOA upper, and build the rest, but there's SO many choices. But I digress...
So, I'll see my buddy in a few weeks, and do the clean/lube avenue with different ammo, and see what shakes loose.
@ntsqd - Thanks for the detailed links. I have all the tools (digital torque wrenches, calipers, etc) except the specific ones, but I may acquire the gun-specific ones, as I think I have one drawer in my rollaway that needs some fillin'.