I'm interested in welding hk sights to my gas block and dust cover of my saiga but before I do, I was wondering...

Will welding affect the chrome inside the gas block? (Cause it to flake or discolor)
And has anyone experienced any cracking or breaking in or around the welded area of the gas block after extended use?

I'm not as concerned about the dust cover since, though heat treated, sheet metal is much more forgiving than cast. I've done plenty of searching on this and so far I haven't seen any issues but not everyone is brave enough to show their mistakes.

This is for my .308 btw and I intend to tig weld it. Thanks in advance.

I would think as long as you don't quench it and let it cool slowly you should be ok. maybe even temper it with the torch after.

Maybe cut a dovetail/solder instead of weld it.

I agree but I'd still like to know how the chrome will be affected.