Originally Posted by 18 Wheeler
I'd also caution against using any of the DIY cold blueing products. They are fine for doing screw heads and small parts but don't give a satisfactory or very durable finish IMO for a whole rifle.
The biggest difficulty may well be stripping the rifle down. The mod.75 is probably the most complicated springer to disassemble and rebuild, with the potential to do some expensive damage if not reassembled correctly.
There are guides available if you feel it's within your capabilities, but not really one for the inexperienced.
That said the Giss guns are my favourite recoilless springers and worth restoring.
A professional reblue including the preparation will be in the £60-100 range depending on condition, plus any postage costs.
The most cost effective method may be to disassemble it yourself, do the metal prep and get it blued/blacked by someone like SPL and then take it to uk Neil (Neil Price) for a service and reassembly.
Here's a FWB mod.150T which I did the metal prep on and SPL reblacked. Fairly time consuming but doable with some basic tools (polishing wheels/ electric drill and various grades of wet'n'dry) and patience.
Excellent advice given the rifle.
I had a FN19 done by Colin Malloy. I stripped everything and took the metal bits to him. It cost me about 50 quid and the reblue was deep and very impressive. FN19's are a doddle though compared to a 75 Giss system.