poly tube transfer port

[Crosshairs]

I hope i didn't get to negative guys if you have time to do it, it cant hurt to try it. after all it is a learning curve and you never know it just might help your gun just because i didn't do much for me don't mean it wont for you.
                                      Mike

[quickster47 †]

That is what I was thinking too.
So am I even a little bit on track, with my drilling the TP, valve comments/ thoughts above?

There was a pretty good discussion on the forum about this the other day or maybe a week or two ago.  I can't find it right now but will look some more.

But what it boils down to is you can drill it out with a hand drill being careful of how you hold it or use some wet-or-dry sandpaper to do the job.  Or if you have a lathe chuck it up and drill it out.

And the bottom line is you might get a few FPS increase but it will be nothing dramatic.

Carl

[1377x]

i use poly tubing in 2 of my high powered pcp guns
neither have the barrel or valve drilled to accept and neither leaks
getting the poly cut just right will do the trick
practice patience then more practice
i cut mine so the breech rocks slightly on the tube then tighten it down.using a clamp to hold to breech to the tube will let you torque the breech down .i have not had a problem with the tube crushing

[tinker]

As 1377x said "High Powered PCP"guns will show the most improvement over stock TP's. A mildly opened stock TP works for most CO2 applications.  Or you can go with Arkmaker's threaded TP mod.

Glen

[Brent]

What is Rich's threaded TP mod?

[woody67]

In my opinion and experience, working with the poly-tubing is really easy. Plus, it's super cheap, so if you make a small error you just throw the piece away you were working on and start over.

When I cut mine, I cut them just a tad longer than the stock TP...since the poly-tube is very pliable, it seats itself in super securely once you tighten down all the breech screws.


You do have to drill the port opening on your barrel and your valve to match opening diameters, but you can squeak by without doing that step. It's silly to have a wider tp than barrel opening though, but you can do it and still maintain consistency in your shots at least.

I've never done a poly tube on a stock 13xx valve, but I did on a few stock 22xx valves and it fit perfectly.  For what it's worth, I don't ever use the stock TP's. I take them out, throw them in my misc. parts/screw bin and forget about them...


One last note on this, I haven't ever built a gun and kept it at a low power setting. I always try to squeeze as much power out of the guns I'm playing with since I use them for pest and critter killing. If I was building a target pistol or was looking for best shot count, I would not use the poly tp.

[KevinP]

I regards to the drilling ... could you just sand down the tubing at the ends to match the barrel and tube ?

[woody67]

i use poly tubing in 2 of my high powered pcp guns
neither have the barrel or valve drilled to accept and neither leaks
getting the poly cut just right will do the trick
practice patience then more practice
i cut mine so the breech rocks slightly on the tube then tighten it down.using a clamp to hold to breech to the tube will let you torque the breech down .i have not had a problem with the tube crushing

That's exactly what I do! Works like a charm, never had an issue!

[ped]

when i do poly ports i open up the barrel port to 4.2mm as well but i only use them with barrels up to 14" as over that i find i can generally get to our power limit with a standard tp set up
ped

[BDS]

Good points Wyo! So if I am following this correctly... this would have an advantage on a stock 2240/ with the valve also opened up?

Brent, the many comments here are relative to each persons experience with specific valve mods or other work they have done to their guns, or maybe no other work done at all!

Bottom line, there is a trial and error window with these transfer port mods, especially with stock guns (kinda like the difference between blowing thru a large diameter paper tube or a small straw, it's a volume/pressure/air speed balance).

Just adding my 2 cents worth for you.

[KevinP]

volume/pressure/air speed balance

indeed 

[1377x]

bds hit the nail on the head again and woody struck a cord too
if you are going to use poly ports open the exhaust and barrel ports too if not just use the stock transfer ports
my ports open up more from bottom to top meaning
exhaust port - .157
transfer port - .161
barrel port - .166
its like a funnel or you can make them all the same size
ideally you dont want to go from small to big then back to small again.i read it causes turbulance when it is done that way.a guy who really digs in tests and experiments with pcp/hpa is where i get most of my info from
i read his posts over on airgunhome joe from hpasports.com aka muzzlemack has a lot of info there also
if you cruise by airgunhome check out threads by yourdaddyjoe,rsterne and iirc gipetto posts or used to post there too
all the folks provide some use knowledge and many more just search out the for the info.
i dont limit myself to one place as i like to hear from more than one source, heck i even read caf canadianairgunforum there some smart guys there that you dont see anywhere else

[Brent]

thanks guys. I appreciate it! Have learned a ton more on this!! Really good posts/ explanations!