Nozzle-to-Bucking Seal and Midcaps

[volteco]

The issue with ocassional low FPS dissapeared after I replaced SPEED head with the Lonex one. I think because the SPEED head has U-cup o-ring maybe it doesn't seal propertly sometimes. I don't have ports in the cylinder so it seems weird to me. I inspected it when I took it out but didn't see any damage.

I am sorry, do you mean tappet spring? Because for the life of me I don't understand how the trigger spring can be on the way of the tappet plate in v.2 gearbox. It is just too far.

Originally Posted by lurkingknight

inspect the piston head you pulled out for a piece missing off the back of it. I had one crack and it no longer sealed.

A heavier piston assembly can increase FPS in certain setups, say if you were building a gun to joule creep.

The tappet can hit the trigger spring when the spring isn't sitting straight, in some gearboxes or with some springs, it will move side to side on the post that anchors it to the gearbox shell.

Are you still seeing issues with your new parts?

[lurkingknight]

the shuttle return spring on the trigger mechanism, not the gun trigger.

Originally Posted by volteco

The issue with ocassional low FPS dissapeared after I replaced SPEED head with the Lonex one. I think because the SPEED head has U-cup o-ring maybe it doesn't seal propertly sometimes. I don't have ports in the cylinder so it seems weird to me. I inspected it when I took it out but didn't see any damage.

I am sorry, do you mean tappet spring? Because for the life of me I don't understand how the trigger spring can be on the way of the tappet plate in v.2 gearbox. It is just too far.

[pestobanana]

Originally Posted by jordan7831

Out of curiosity, what fps variance would you consider acceptable? Say I have a gun with +/- 2 fps variance from the average. Would you consider that to be a fairly consistent set up?

+- 3 meh
+- 2 good
+- 1 up to par, but doesn't stay that way long if you game it

[pestobanana]

Check the interior of your hop up lip, see if it is nice and round. Switching from PDI to Prometheus should have increased your FPS. If you're trying to troubleshoot issues, maybe you should change one part at a time instead of two or three.

What cylinder are you using? With Lonex piston heads I've found that they seal differently to different cylinders, giving out different FPS outputs despite seemingly good seals when pressing the piston forward.

[volteco]

LOL I know, but I must have taken apart the gearbox 20 times already, just trying to cut down on assembly/dis-assembly process.

I was using stock VFC cylinder. Last night I changed cylinder, cylinder head (war bear) and nozzle (Prometheus). Managed to get the nozzle seal this time. Gun now shoots consistent 407 FPS with no hopup engaged. I still think there is air loss somewhere since I was able to get 425 FPS on the same spring. Will try the SPEED head on a different gun and see if the head contributes to it...

Thank you everyone for the help!

Originally Posted by pestobanana

Check the interior of your hop up lip, see if it is nice and round. Switching from PDI to Prometheus should have increased your FPS. If you're trying to troubleshoot issues, maybe you should change one part at a time instead of two or three.

What cylinder are you using? With Lonex piston heads I've found that they seal differently to different cylinders, giving out different FPS outputs despite seemingly good seals when pressing the piston forward.