Gamo Magnum

 This should be an interesting project. There are a few missing parts, the rear spring guide being the most difficult. I have been looking but haven't found much information on the 1980's vintage Gamo rifles. I did find a parts manual online for a Gamo 900 that appears to be very similar. 

The thing that makes it a "Magnum" appears to be the ID of the compression tube, it measures at 1.145 inches or 29 mm. I measured for a spring and a .120" wire 31 coil will fit... seems a bit small for a magnum
(you can right click on the pics and open in a new tab to view a full sized pic)

There was no seal on the piston.

I found the old seal....in the bottom of the compression tube.

It took some work to get the old seal out, it was stuck tight, crumbling and came out in crumbs the consistency of crayons...

I'm not sure how it got in this condition.... I suspect there was heat involved and maybe some lube added to the compression chamber. Regardless, the tube looks good and should be fine.

It looks like a nice adjustable trigger.

The rear sight is decent, nice adjustments with crisp clicks. 

The wood looks good and the stippling on the pistol grip should help with getting a good grip.

There is a roll pin instead of a cocking shoe, this is the first time I've seen this set up. The blueing is worn in a couple spots on the cocking linkage but there is very little wear on the contact points, leading me to believe this air gun wasn't shot much.

I'm pretty impressed with the quality of the parts, everything seems to be well made. It should be a good shooter when I'm done. I'm working on a spring guide and a Gamo 1250 seal that I hope can be adapted to fit is on its way...