Tuning open escape hole larger?

[harrympope]

a fellow on another non airgun forum gave advice to enlarge the escape hole to gain 100 fps velocity.
new one to me,I'd think there could be a chance velocity could drop due to pressure drop.

on a spring gun of course.

my terminology for the little hole at the end of the chamber that the air pushes the pellet base may be wrong . I'm open to being corrected.

 

[Bear-of-Grayling]

Welcome. It’s called a transfer port. You are correct. Opening it will reduce power and could permanently damage the gun.

 

[harrympope]

Welcome. It’s called a transfer port. You are correct. Opening it will reduce power and could permanently damage the gun.

thanks, I wasn't sure if the name was the same on a piston gun as a pcp.

 

[DesertSilver]

If you make the transfer port bigger than it needs to be you'll lose power. There's only so much pressurized air available and if the volume of the transfer port is to much it will take away from the air pushing the pellet down the barrel. That's why having a longer barrel on a springer doesn't always translate to more power like it does for a PCP. Springers seem very simple in comparison to a PCP but there's a whole lot of engineering that goes in to it.

 

[Sawney Bean]

It’s an interesting idea to really open the port up and shorten the barrel to an ultra carbine though. Definitely not something I’d want to do with a Theoben, but maybe with an old Gamo.

 

[beerthief]

wouldn't opening the transfer port cause piston slam , as in no back pressure ? possibly ruining the seal ?

 

[Chuck-in-Ohio]

wouldn't opening the transfer port cause piston slam , as in no back pressure ? possibly ruining the seal ?

Yes
If you go too large, then that would be a very real possibility. It involves more math than I care to figure out.........