Had a bcm gas low pro gas block that had some damaged threads from removing it ( guess it had material caught in the threads when it went on). Retapped the threads for good measure but now when you insert the set screws the threads feel loose and you can wiggle the set screws a bit in the threaded holes. That normal ? Should I use it or get another one ? Sorry for the question, never retapped threads before.

Get another gas block.

Gas blocks are not expensive.  Sweating over redoing threads, then “what if I got it wrong,” or “what if it moves anyway” are “costly.”  Get a new block.

The hardest part, for me, of installing a gas block is getting it into position.  Everything else is just details and technique.

You probably used a cutting tap and not a chase tap.

using a cutting tap on messed up threads will usually removed material and cause loose screw engagement.

Yup that’s probably what did it

I don’t have a “selection” of cutting, bottoming and chase taps.  I have a couple sets in specific sizes, but mostly I have either cutting or nothing.

So when it looks like I have to chase some threads, I get a fastener of the right size and just thread it through the hole.  That will either fix lightly goobered threads, or tell me that the threads are really bad.  And if I mess up a “5 for $0.30 bolt”, oh well.

I did not come to this in some philosophical epiphany.  No.  I severely destroyed a threaded hole once by just ham-fisting the only tap I had for that size: a (really nice) Craftsman cutting tap.  I’m not sure if I angled the tap, or didn’t quite align it and cross threaded it from the start, but those threads were essentially history after just a few good “strong” twists.

Now, I am very mild and gentle when I try to start most fasteners, and extremely mild with any thread cutting tool.  I’m teachable, just slow.