Hello mate,
If its just a little scratch then these pens do an OK job, but it depends where the mark is, to do a full re blue on your gun isn't a quick job, i,ve done a few in my time and there,s a lot of work involved, another way of doing a scratch is by using an indelible marker pen, that's all we used years ago, and done right you get a very good finish, hope this helps,
Rob,
thanks for the reply mate think i will give 1 ago there cheap enuf