Educate me on Piston Weight

[leeben]

My 77 has a 25mm standard piston but the comp tube has a radius in the back of the transfer port of about 6mm wide and 4mm deep,standard port width in the front.who done the work? I don't know.
the action is .177 I'm using jsb 8.4g the spring came from a .22 'unknown origin' very slim it's level with the rear of the action so only loads when the block is fitted.
V-Mach lube on the spring and dri-slide in the tube. It's doing 11fpe with 3fps variation I was very shocked when I put this together to say the least. I just built it from parts I got here n there. It hits what I point it at lol. Love it much more than any of my PCP's.
ps,first time I built it it was doing 10.2fpe and was ok then I added a 2mm delrin power washer so it was 11fpe this made it so much smoother it's unreal. Anyone have any ideas on this?

lee.

[airborn68]

Hi Guys
I have been following your various post on Short stroking the Tx which has inspired me to have a go.
Have moded the piston to take a Vortex HW seal weighing in at 206g. 80mm stroke with extended rod.
Now you have got me thinking about skimming down the TP to 7.5mm, what's involved with letting the barrel through on the mk 3 not had one stripped that far.

Regards Jon

[brucegill]

Hi Guys
I have been following your various post on Short stroking the Tx which has inspired me to have a go.
Have moded the piston to take a Vortex HW seal weighing in at 206g. 80mm stroke with extended rod.
Now you have got me thinking about skimming down the TP to 7.5mm, what's involved with letting the barrel through on the mk 3 not had one stripped that far.

Regards Jon

Hi Jon

You don't need to move the barrel for 7.5mm TP. You only need to do the barrel if going to 5.3mm (sorry, that size may be wrong, memory is fading today).
You take 2.5mm away from the inside of the comp tube plug. but don't forget it will effectively change your stroke as your piston now sits 2.5mm further forward.

The mid length port is one of the best mods I've done to mine. (obviously the stroke is the number one mod). And the HW seal!

As for stroke length and piston weight, I think thats all subjective.

[airborn68]

Thanks for that.
I have a couple of spare pistons & rods and another comp tube on the way.
My plan was to have various set ups that I can try back to back & find one that I like.

Cheers Jon