The Crosman barrels are all 7/16" what fits the pumpers fits the 2240.A flat top piston and or a longer barrel will boost velocities you can cap at just under 500 fps. I'm having a 2289 14" barrel done and have a custom 2240 with 10 " barrel that is lights out on chickens at 20 yards head shots are easy.Shoulder stocked into a carbine 495 fps with a 14.3gr pellet.Steel breech added to both for strength and scope mounting topped with a 4x Banner 1" Lothar Walther makes a match .177 barrel in 10" length if accuracy is paramount.D+L airgun in BC has barrels.
^now THAT sounds interesting...
To the question~I got a 1377 for my 16th birthday, that was 33 years ago. It was used hard for a almost 20 years, had it's seals done 2X...and has mostly sat dry-docked ever since. Shoots hard still, doesn't leak air. At the time, Crosman offered this gun with the black, 1399 "carbine"/skeletal stock, but the pistol grips came with it too. Boy..if that 1377 could talk.
I use it once in a while now, mostly for nostalgic reasons....but I've often thought I'd like to buy one of the new 1322s, and a fresh 1399 to go with it. Maybe I'll pick mbogo3's brains a bit...see what it might take to get a stocked 1322 (still shooting 12g CO2) up around the 490s. Would be a fun, light, hard-hitter.
I think they're hard to beat honestly, and if anyone can make a -$100 pump-up air gun right, it's Crosman. I can even attest to their ability to penetrate, thanks to some carelessness on my buddy's part. (kids+late 70s+no parental supervision) I got lucky, but there may/may not be a .177 watcutter somewhere in my body. lol