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small transfer port advantage?

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When using balanced valves have found using VERY small transfer ports tightens up the ES value, uses less air with minimal cost to power produced.



Using tapered throat transfer ports that leave valve throat at .25

A 60 ft-lb .25 cal running on a .180 / .250 transfer

A 53 ft-lb .22 on 165 /.25

A 30 ft-lb .22 on .140 / .25

A 20 ft-lb .20 on .110 / .25



With a balanced valve that vents to throat greater the back pressure faster the valve closes while decreasing dwell
 
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Beautiful custom work on your Bantam! That’s a powerhouse!
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Thanks! I ditched the scopes for a holosun green dot and just looooove the gun so much more now. 11 rattlesnakes this year so far! Most inside 25 yards. I got one at 80 yards by luck i spotted him curled up on a rock which gave me a nice fat visible target. You guys havent heard anything yet until you hear a 34gr jsb at 990fps hit a rattlesnake when its balled up lol but anyway back on task..
 
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I’ve been playing around with port sizes on a unregulated gun in .177. My original goal was a long flat string but didn’t take power into account. I had a nice 40 shot string with only about a 3 percent high/low curve. However it wouldn’t even mark the paint on a 1 inch spinner at 40 yards. So then went to a much larger port and got the power but only a 20-25 level high/low curve. So I took a small port and started drilling it out in increments. It seems that with each port size there is a fairly level curve but if I try to push that port for more power I will get a steadily descending curve. It appears to me each port size has a sweet spot with pressure, spring tension, etc. I’m sure I am reinventing the wheel and that tons of members already know what I’m figuring out but sometimes doing is learning. 
 
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I’ve been playing around with port sizes on a unregulated gun in .177. My original goal was a long flat string but didn’t take power into account. I had a nice 40 shot string with only about a 3 percent high/low curve. However it wouldn’t even mark the paint on a 1 inch spinner at 40 yards. So then went to a much larger port and got the power but only a 20-25 level high/low curve. So I took a small port and started drilling it out in increments. It seems that with each port size there is a fairly level curve but if I try to push that port for more power I will get a steadily descending curve. It appears to me each port size has a sweet spot with pressure, spring tension, etc. I’m sure I am reinventing the wheel and that tons of members already know what I’m figuring out but sometimes doing is learning.
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still following

Please keep inventing that wheel!

Those of us born after after the transition from wooden wheels to alloys could learn from the experience


 
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Hi vmaxpro I have a Brocock Bantam Sniper HR .25 and have just discovered your posts and love what you have done to yours. My gun is curretaly worse that yours was when new, I am getting around 40 shots at 825fps at 150 bar with 25.39gr JSB kings. I have tried different springs spring tension and hammer stroke settings but that seems the best I can do. so I would like to make some improvements and have some questions . 

I looked at porting but the power adjuster doesn't have much meat to play with, how did you deal with keeping the power adjuster intact? Did you make it .225 all the way thought to the barrel ?

I see you moved the regulator to just behind the bottle. Would doing this and removing the original regulator give some more room in the body to act as a plenum? I'm not sure I'm ready for 150cc bottle.

Can you tell me where you go the free flight hammer with Stopping Spring Guide from ?

A few pointer would be appreciated.

Cheers Jon 

1592040965_15040938245ee49e0534b739.15441287.jpg

 
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