Wow, these things are...
Pieces of shit.
We'll start with it's inaccurate as hell. I went back and forth between the 502 and TX22. TX is one hole groups, 502 is a six inch pattern, tested between multiple shooters. Hell, tested between multiple guns since my buddy had his TX and 502 at the same time with the exact same results.
Other gripes:
Have to baby the magazines. I did a normal reload like I would a glock at the range, not some competition level slam, just surely insert, and the base flew off. I reassembled it at the bench and recreated the error multiple times.
Next, the slide is flat out lazy. Its glacially anemic using the release, and fat guy getting off the couch slow when slingshot-ing.
The trigger shoe is too fat - which yes, is a personal preference - and the reset is too long. I can deal with long, but it's just over the line of too long.
The screws they send with the plastic plates to mount your sight don't have the right tbevel so there's a gap even when tightened.
Overall, I'm pretty stinking unhappy with it, mostly due to the accuracy. FN touted this as an accurate combat level trainer. Ummm, no.