Well I got my new TF-59 yesterday evening. First thing I did was pull off the stock and look at the trigger assy. They did a great job of almost duplicating the Gamo trigger..
I was curious to see if it would take a GRT-III trigger. Well almost would but the fat pin in the TF had a smaller fat end.. So it would be loose in a GRT-III trigger. It was late and getting cold so I waited until this morning to start working on the TF. First thing I pulled off the trigger assy. from the action. Then I put her up into my spring compressor and got her set up for extracting the internals. After I got everything apart and laid out I measured the fat pin hole on the GRT-III trigger. Since the fat pin just floats in the GRT blade and acts as a travel stop, I decided to make a fat pin from brass. After turning it down in the lathe I tested the fit and made a couple of adjustments. Wa La it was done..
Now for the rest of the TF. As usual the spring guide was made out of funky steel, similar to the ones in the Gamo air rifles. It was a floating guide with a head on it. It would seat in the recess of the spring block about 1/64". So I made up a new guide out of delring and fitted it to the original spring which was new. This spring had 42 coils on it and was kinda small in diameter. It could of been allot larger because the difference of the I/D of the piston was quite a bit. Spring kinda flopped around in the piston. So I decided to mod the piston with a piece of delrin. So I measured the I/D of the piston and cut me a piece of delrin where it would be a very tight fit in the piston. Pressed the solid piece of delrin into the piston. I then mounted the piston into the lathe and drilled the hole out from rear to front. After I drilled the hole big enough I took my boring bar and turned it down till I could slide the spring all the way to front of piston. Now I had to figure out how much more I needed to take out in order for when the spring expanded when cocked there would be no binding. After finally getting the right size I wanted I put some spiral groves from front to back. This would hold the heavy tar in place when spring was collapsed and released.
Now was time to do something with the seal. The TF had the generic Chinese screw that held a hard nylon seal in place. Since an Apex seal was what I was going to use I had to make a cone with recessed hole and the right taper to accommodate the Apex seal. So again I chucked up a piece of delrin in the lathe, drilled and cut the taper for the proper angle. Now I could use the new Apex seal on the piston to replace the old hard nylon seal.
Next was to debur the rest of the pieces including the action, piston, cocking shoe etc etc. After I was done with the deburing I cleaned everything up and finished off the combustion chamber with a hone cross hatch. Clean the action once again and then laid everything out in front of me. I double checked all the measurements and pieces I had worked on to make sure I did not miss anything. Which I did..
I forgot to make the stainless steel washer to fit the spring guide and another on between the bottom of piston and the spring. Had to cut the I/D out of one washer and cut the O/D down to accommodate sitting just below the O/D of the guide and of course fit the guide shaft itself.
Ok now I was ready to stuff everything back together. Got everything compressed and the spring block pins in place and now I put the trigger assy. back in place. Put the barrel and breach block and cocking lever back in place and adjusted up all the hardware for proper fit.
Now I installed the stock and buttoned her up. Wiped everything off and cocked her to set the spring. Cocking was very smooth I might add..
Now for my first shot out the door. Was very surprised at how quiet the report was. So I shot off another 10 to 20 pellets and boy she even got quieter. Now they advertise the TF-59 .177 to shoot in the 900 fps range. As usual they lied..
I did take one shot over the chrony before I started and she shot at 824 fps with Gamo Hunter's.
The first shot over the chrony after the tune was 835fps, then 825,829,833,832,829,834, 827,828,831. Not a bad 10 shot deviation..
To say the least, I was very happy with this 10 shot reading. I will re test after a tin of pellets to see how much she comes up if any at all.
The best thing I liked after this tune was the smooth cocking, quiet and smooth firing cycle and low report noise. I have wondered for a while now about putting a delrin sleeve in an air gun piston and now I know it can be done. Not many air rifles have as much room between the stock spring and inside of piston. After making the liner for the piston the thickness of the liner was .066 . Now the spring makes no contact with any metal, which attributes to avery low action noise when shooting.
