Torpedo reg strangeness

[RhoXi]

I picked up a Bob Long Defiant 2 a while back and it's never shot quite right. It has the stock lpr, a CP vasa, and some flavor of torpedo hpr. As best I could tell there was some sort of recharge issue occuring causing the gun to cycle very slowly. The forward stroke of the bolt was fine but the return stroke was noticably slower and caused shoot down over 5bps. Occasionally I could hear a faint squeaking sound from the hpr after a shot, as if the reg piston was moving very slowly.

I rebuilt both regs twice with standard 70d buna orings and no dice. Replaced them all with 70d quad rings and it got a little better but would still act like it was starving for air half the time. I swapped the torp with the evil detonator I have on my Promaster and, wouldn't you know it, both guns now shoot fine.

My question is why would the torpedo barely work on the Defiant but work fine on the Promaster? Am I going crazy or shouldn't the sprung ram of the promaster have made the recharge issue more apparant? Anyone else have a similar experience?

[flyweightnate]

Might have to do with the volume above the piston/ in the gun itself.

I had a torpedo that would act funny like that. I figured there was probably a slow leak around the piston so I drilled a vent next to the adjustment screw. Shot way better afterwards.

[RhoXi]

I was thinking of doing this exact same thing. Definitely going to try it now.

[Frmrspec]

lol I thought this was a pic of one of my regs.. I did that to all my torpedo's

[flyweightnate]

Once you know, it's hard to unknow!
I had a similar issue on a crazy build in college, so now I just assume every piston leaks over time.

[RhoXi]

Did some more testing last night this is exactly what's happening. The recharge rate starts dropping then the reg starts to over pressurize. It almost blew out my mini gauge! Air is definitely getting around the piston and pressurizing the lower chamber. How big a hole should I drill? Luckily I've got access to a drill press so it shouldn't be too difficult.

[flyweightnate]

Did some more testing last night this is exactly what's happening. The recharge rate starts dropping then the reg starts to over pressurize. It almost blew out my mini gauge! Air is definitely getting around the piston and pressurizing the lower chamber. How big a hole should I drill? Luckily I've got access to a drill press so it shouldn't be too difficult.

Tiny is fine - 1/16" will be way bigger than the leak.

See if you can flex-hone the piston bore if it looks scratched, and check for nicks on the gland (oring groove) on the piston itself.

[RhoXi]

Will do, thanks!

[flyweightnate]

This is the bore of my torpedo... I guess I know why it needs a vent

[RhoXi]

Yep that's about how mine looks. It's a shame because the outside is a lot better shape.

[RhoXi]

Alright, I dilled a hole in the reg body to vent the piston. Then I aired it up and it still was over pressurizing. Pulled the whole thing apart and found the buna reg seat I had gotten from the previous owner was shredded. I've got the proper seat on order now but I think the vent hole should help with the recharge issues. Thanks again to y'all!

Edit: Update for those curious. The new reg seat and vent hole have eliminated the issues the reg was having and the gun shoots great now. The vent hole was easy and I recomend it if you don't have a vented adjustment screw on your torpedo.