Tuning E Rowe Transfer Port

[cra627]

I did just a quick chrono today with Mr. Rowe’s new transfer port against my Huma and stock port. 10 shot strings through ProChrono.

Using my 25 Crown at 150 bar with modded pellet probe and Nielsen 29gr slugs (new slug probe hopefully this week and will test again). 600mm superior heavy liner. The gun was tuned with the Huma. 

Stock - 921fps avg, 11 ES, 4 SD

Huma - 941fps avg, 6 ES, 2 SD

ER - 932 fps avg, 3 ES, 0 SD

So fps loss but great ES and SD numbers so Ive left the ER on the gun and will play with the tune but probably after slug probe install. 

 

[Eaglehorn]

Surprised there isn't more FPS on it. Would like to see what others are getting. That's very interesting how your ES went down.

 

[cra627]

Yes i was surprised also about fps. I have a couple spare hours tomorrow so will shoot as-is for accuracy then tune a bit. Ill post anything interesting. 

 

[bigHUN]

Can you post a picture of Mr. Rowe’s new transfer port?

Please take into consideration the transfer hole in a rear block is 7.2 mm OD. That is a physical limit, no matter what you do with a Huma brass piece.

That one in a center is my Huma mod, and is maxed out (also enlarged the pin opening as well to the brass piece). Next thing is to take the rear block + valve housing apart and tinker there, but cannot source new parts to have spares if anything goes South.

 

[cra627]

Ok I wasn't aware of that but understand the 7.2mm limit. Not great pic hope you can see - ER looks to be maxed. Thanks for your input. 

 

[bigHUN]

Ok I wasn't aware of that but understand the 7.2mm limit. Not great pic hope you can see - ER looks to be maxed....

One more thing you can do to polish the center wall section into knife edge carefully or put some radius on top edges in between the pockets and that is the max we can do. Still not sure if that worth the extra maybe... 5fps?

If you need more power/speed be prepared for deeper internal surgery.

 

[sniperlabyo]

My port is mostly designed with a 10 to 9mm TP on the rear block to bore out from stock of 7.25mm TP to take vantage of nozzle opening of 11mm in my port. With 9mm TP in the rear block will gain another 25-40 fps. If not used on high power more you will loose 5-10fps due to pressure dope with the 11mm opening of my port.


if you mod my port bridge with knife edge entrance you won’t gain any FPS.

The main purpose of the dual port is the bridge that provide a smooth passage over the PT, if you look underneath the PT and push a ammo vary slowly you will see the ammo slightly dip in the TP without jamming on a stock TP size now i have seen guy elongate or enlarge the TP that results in more dipping without jamming but getting nicks and you know if you go to big the ammo will jam.


watch this video and see the ES, my Dual port was used.



https://youtu.be/jZxGVkGikHs



Cut away view rear block TP, see more flow on the side with 9.22mm port. I have a custom mill bit to enlarge the TP without enlarging the M8 set screw.

Ernest

 

[allenbowles]

what about a stock port chrony numbers?? imo you just showed us a good reg.tune...??

 

[sniperlabyo]

The nozzle design maintain more consistent pressure behind the ammo. 


will provide reg tuning video soon — lost of details deburring and polishing 


Ernest 

 

[douger]

id say that gun is tuned up very nice

 

[knifemaker]

Sweet!



KnifeMaker

 

[JRR]

You share so much with all you are the MAN!! I would still be in the slow lane @ 840 FPS

 

[Airgun-hobbyist]

I use a Dremel tool and bit like this to go through the threaded hole in the block to enlarge that port. Put a couple wraps of masking tape on the shank and it won't harm the threads and you can also use it for a size guide for opening up the port to a specific size (to match the brass transfer port hole.)

 

[schlupsa]

How much for the Ernest transfer port- link to buy?

THX

-steve in KY

 

[cra627]

https://910airguntuningandrepairsllc.com/products/fx-stx-barrel-dual-tranfer-port