Thanks for the video link. I had to get a beer and start dancing while watching. I will look into the upgrade and barrel.
I would not waste to much money on the 66.
Unless you have that desire to play with stuff like this. You would be better off buying and tuning up a nice vintage 1400 or 392?
The trigger work is pretty much a polishing job.
Get some nice fine paper or some really fine stones. Polish all the contact points. Including the pivot pins.
Make sure the barrel crown is in good shape....
Few problems with getting more power.....more pumps. I'm not sure how it works but the idea is to have the same volume of air in your valve as the volume of the barrel and all the ports it travels through.
This makes for a very efficient push of the pellet down the barrel.
It's been a long time since the 66 I had. Trigger polish took a good 2# off and the fuel was so much better.
I played with hammer weight a bit buy placing some small lead balls in the back. This also shortens the "spring" some.
Problem with this is the spring wears into the lead and slowly beats the lead ball into dust.
Down side to this is it can put some heavy wear on your valve stem.
It's a balancing act.
The few things I did that seem to help the most is removing any rough edges at the air ports.
Thinking back I could have bought a better rifle but I had lots of fun trying to get that old 66 hitting hard.
No crony back then so 1/4" fiber board was the test. Stock it stuck in. Heavy hammer/spring stuck in deeper. Increased volume of valve took more pumps to get it to stick and a few more to go through.
Accuracy was best at lower fps. Seems anything above 600 out of the 66 didn't fly well.
A good day was dime sized groups at 15 yards.