Short stroke 80 Loud!

[maximus]

Hi, my 177 60mm stroke 80 shoots nice, good power, low recoil but seems to have quite a crack with it on firing. What would do the BBS tuners think the causeof this could be? TP is about 3.5 btw. Bit slammy from too much spring perhaps?

[Shed tuner]

they are louder.. higher barrel pressure at pellet release...

Shoot it with different weight JSBs and see what energy differences you get.. gives an idea of it's got too much preload, e.g. 7.9s and 8.4s ?

[TonyL]

As Jon says, give it a try with those different pellets.

That's quite a short stroke you're running. Different rod or head? To my mind, you're having to work that reduced volume a little too hard and a short stroke / wide bore won't be as efficient as a longer stroke / narrower bore set-up with the same swept volume. I think a stroke value in the region of 66 to 70mm will provide a softer feel? Playing with piston weight may help, too.

[john79]

Does it have a silencer on it? my 177 80 had a v-mach kit fitted and it had a silencer ...it was very quiet

[maximus]

Thanks for the replies lads. It is fitted with a steel vmach Silencer but they are not the quietest, just look the coolest. I'll do a bit of chronoing and post the results. The piston is lightened by having holes drilled in it but I added weight back with a steel top hat. Accuracy is good with 8.4 job's. Will chrono with the 7.3s and see. Probably did when I was setting it up but can't remember the Results.

[Mach 1.5]

I think the piston may also be the problem. Try one without holes drilled in it. Too many causes a drag factor with the airflow. Mach 1.5