Most FPE from a 13xx?

[Noah]

the most i squeezed out of a 13xx was 20fpe
i used a heavy hammer spring, 14.5" 2250 barrel,increased volume valve flat topped, a .22 beeman kodiak 21gr pellet and 35 pumps

The most I ever got from my modded 1377 was 791 fps with a totally light 5.2ish grain pellet = 7.23 fpe. I am going to add a 24" barrel just to see the difference compared to the current 18-incher...

[1377x]

The most I ever got from my modded 1377 was 791 fps with a totally light 5.2ish grain pellet = 7.23 fpe. I am going to add a 24" barrel just to see the difference compared to the current 18-incher...

did you open your valve up for more volume? that might the difference
also i opened the port on my barrel
from what i have read upping the volume and opening the ports doesnt help .177 too much .i guess those mods are for.22 and up
the exhaust port is huge and the angle has been heavily modded
i used a .22 beeman kodiak 662fps to get the 20fpe that was 15 feet from the chrony impact velocity.muzzle velocity would be higher
as far as .177 goes ill have look back at my first posts to get any numbers.i do remember getting 650fps using cphp, the stock 1377 barrel on two different guns using a valve and piston from two different makers.
guns that i built on the phase three platform didnt perform as well as the earlier phases
on my phase two the valve was modded by myself and a local air gunsmith he also used a phase one 760 piston in my gun.the second was a phase one 1377 almost stock except the pre load on the hammer spring accustoms valve and piston.it shot 660fps with cphp.both guns 10 pumps
all my guns get the fps verified at the air gunsmiths shop and my chrony.the numbers are very consistant.i couldnt believe the numbers myself thats the only reason i take them to the shop for a second fps test .the ag shop uses an old oehler chronograph, i use a f-1 chrony

[Noah]

did you open your valve up for more volume? that might the difference
also i opened the port on my barrel
from what i have read upping the volume and opening the ports doesnt help .177 too much .i guess those mods are for.22 and up
the exhaust port is huge and the angle has been heavily modded
i used a .22 beeman kodiak 662fps to get the 20fpe that was 15 feet from the chrony impact velocity.muzzle velocity would be higher
as far as .177 goes ill have look back at my first posts to get any numbers.i do remember getting 650fps using cphp, the stock 1377 barrel on two different guns using a valve and piston from two different makers.
guns that i built on the phase three platform didnt perform as well as the earlier phases
on my phase two the valve was modded by myself and a local air gunsmith he also used a phase one 760 piston in my gun.the second was a phase one 1377 almost stock except the pre load on the hammer spring accustoms valve and piston.it shot 660fps with cphp.both guns 10 pumps
all my guns get the fps verified at the air gunsmiths shop and my chrony.the numbers are very consistant.i couldnt believe the numbers myself thats the only reason i take them to the shop for a second fps test .the ag shop uses an old oehler chronograph, i use a f-1 chrony

WOW - I have no idea what is indside as it as a MountainAir masterpiece - Roy does good work, yeah 

From what I remember, it was after 12 pumps....