I'd like to swap the front sight on my ZKK 602 with a NECG masterpiece, also so that I can fit one of their flip up nightsights to it.

However the front sight and ramp on the rifle are not screwed in place, I suppose they are "sweated" or soldered on?

In any event I don't know much about either procedure, but I'd imagine that by applying heat it should come off?

How tricky a job is it to take the old sight unit off and install the NECG unit? I don't mind trying it myself, as long as I don't risk compromising the integrity of the barrel itself.

Obviously it will need rebluing afterwards, which is another problem altogether.

So any help would be appreciated.
Thanks.

I am not familiar with that particular rifle but can only guess that it was soldered (brazed) on. The other option would have been to machine it integrally with the barrel, which I doubt.

If it was brazed on, my take on it would be to machine it off. I firmly believe the heat necessary to remove the sight would damage the interior of the barrel. As long as you are going to refinish it anyway, it would not matter to machine it offf.

I too am not a fan of unnecessarily heating a barrel because of the potential for bore damage, but, if you have no choice, then you can obtain some "heat control paste" from Brownells to coat the bore and then apply the torch to just the sight. Warm it quickly and evenly, paying attention to the joint. When you see the Solder become fluid, tap the sight sideways to break the grip and then off.

If you're using heat, mount the barrel upside down so the instant the solder melts the sight drops off. As Westpac says, apply heat to only the sight and it also helps to apply a little pressure with a fine scribe or ice pick while heating.

Also, if you do insist on heat, If you plug the barrel and then fill it with Argon it will keep the bore from getting screwed up. The Argon is heavier than regula air (O'2) and will displace it when you bleed it into the bore.