Bob,

Absolutely brilliant thread and information, thank you.
I have one of these, to which I've fitted a steel breech conversion and shoulder stock. I don't have my notes to hand, but I seem to remember that it's doing 4.6 ft.lbs with 10 pumps using Hobbies.
I've not played with it as far as any further tuning to date, but may well do so in the future.

There's a lot of very useful information in your write-up.

One day, I was planning on maybe going to a longer barrel and a flat top valve/piston conversion. Depending on who you listen to, with the shoulder stock screwed on it'll be classed as a rifle, and at say, 9ft.lbs it'd make a lovely little light weight, recoilless, self-contained field gun. Now that the 1322's available, may go for that instead.

With the 1377 have you played with different pellet weights to ascertain power? What I'd be wondering is...generally with a PCP / pump rifle, muzzle energy would be higher with a heavier pellet. Would this still apply when we're talking pistol power levels?

Looking at your user name and location.....If you're into bikes, and live in Sheffield, feel free to drop in at my place of work....SMC Bikes. I won't be able to talk for TOO long before I get glared at, but it'd be nice to meet and have a chat.

Not many Airgun fans, especially Crosman fans that I meet face to face!