[Styrak]

So I've had a KA M4 GBBR for a while, put a different rail and barrel etc on it. However I've never used it since it had some hopup issues (which I think I've resolved by putting the original inner barrel back in) and the bolt catch and bolt carrier where it catches wears down after about 3 magazines.

I've filed it straight again, but it's such shitty metal that it just wears round again and slips, so that it doesn't catch on an empty mag.
Do I need an aftermarket WA/G&P steel bolt catch and carrier? Or will a standard G&P one hold up fine? Don't know if the stock G&P ones are crap metal too, or actual stand up to wear.

Help?