I have put in a valve and port from alchemy airwerks. I also have the steel breech, and a 24" barrel.
This is a 1322 platform, I have managed to pump it up 18 strokes. Any suggestions as to the optimum barrel length? I don't have a chronograph so I have no idea of the velocity. I am using Crosman round nose pellets. ???
It's usually somewhere about 18" but it also depends on the powerplant, propellant (CO2 v. HPA), and pellet/bullet weight. I'd leave the 24" alone if it's shooting well! If you're just a shooter and not a tuner then just have fun and plink away! A chrono will for sure make one worry and tinker. Sometimes I like to make sure I just go awhile without even turning on the chrono!
The barrel length has been discussed and debated a lot. I'll just leave it as what you like as to comfortable handling and appearance.
As to number of pumps, this is very interesting:
http://www.gatewaytoairguns.org/GTA/index.php?topic=77463.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=77463.0)
I agree leave it be if it shoots.
Glen