Transfer port size?

[daved]

I recently got a Hammerli Pneuma, and in the process of tearing it down and "tuning" it up, noticed something that brought up a question. What's a typical/reasonable transfer port size for a .177 PCP? I know this thing is wasting air, it's noisy and the shot count is dismal. I think it's the port size, the rest of the power train seems pretty well balanced. The current one is about 4.2mm, seems excessive to me for a .177, even if it is a hammer. Any suggestions here? TIA, people.

Dave

[Leadhead]

Dave, I don't know much about transfer port size, but I was able to dig out a paper I had printed out not too long ago. It was by The "A" Team, about tuning Benjamin PCP's.
According to them, "It is rare that a PCP needs a transfer port larger than .110 to achieve 20 ft/lbs." They say that some rifles have larger transfer ports because they were designed to work with CO2 as well................maybe give you some ideas..............Raoul

[DanoInTx]

.110 x 25.4 = 2.794 or just a hair under 2.8mm, sounds good to me:)  Grab your calipers Dave, let me know what this thing looks like and I'll see if I can turn you a couple.

[daved]

Thanks, Raoul, that's exactly the kind of info I was looking for.

Dan, next time I take it apart, I'll make some detailed measurements.  I was thinking around 3 mm sounded about right for a starting point, over 4 seems ridiculous.  Haven't had much time to shoot lately, let alone take it apart again.  And on that subject, why am I sitting at my computer when I could be sitting at my shooting bench ?!  Later!

Dave

[DanoInTx]

It's cool I haven't had much time for turning stuff on the lathe, I've been too busy being on vacation:)  I took last Thursday and Friday off, and also this Monday....then I worked today and yesterday and I am taking Thursday and Friday off again.  It's not all fun and games though, Janet is getting her wisdom teeth pulled in the morning and I have to be the "parent in control" for a few days before she feels better and kicks me off her throne...haha!