GBB Question
 

What can cause my HFC M190 slide only locking back when i press on the bottom of my mag?

PROBABLY your mag catch has worn so now the mag sits slightly lower in the mag well not allowing the slide lock to be pushed up fully, the same thing happened with my glocks.
you need a new mag catch

Why did you start another thread?

i thought i should of starteed a new one because its another question

i took out my mag catch and it doesnt look like its worn down

At least the KSC Glkocks have a stamped steel slide catch so all you have to do is use some pliers to gently bend the part that catches the follower down a bit to fix it (happened to one of my G19s, I fixed it). Not recommended for other guns that have a cast slide catch though.

Then maybe you have to buy a new one. Probably isn't that expensive.

but what its not worn down