Transfer port length, what's the best?

[maximus]

This is the sort of info I was after, I have read that longer ports produce a softer shot cycle but good too long and efficiency is compromised.

[Shed tuner]

first question - what kind of shot cycle do you want ? smaller/longer-softer - but obviously that can go too far and lose efficiency quite quickly.

ballpark I'd be looking around the range of 3.5mm x 6mm to 3.0 x 10mm

[maximus]

I think I will go for 7/8mm. May even look at interchangeable transfer ports for experimenting.
I started drawing it up last year and only picked it up again yesterday. So far have done the breech Jaws and cylinder, breech block and barrel interface. I even bought a second hand TX so I could measure up for swapping parts over. Looking to use the piston, trigger assy and stock.

[Benelli B76]

This is the sort of info I was after, I have read that longer ports produce a softer shot cycle but good too long and efficiency is compromised.

That is illustrated well in the Gamo Paratrooper repeater, massive spring power, but low ft.lb. energy out the barrel.


Baz