Tuning Exchanged my barrel probes on my Fx Crown today. I\'m confused...

[MoeHofer]

So these huma aftermarket barrel probes are supposed to increase my velocity on my crown by an average of 30 fps, or so I was told. 

I swapped them out today and actually LOST 10 FPS on my 700 mm barrel. 

What in the world is going on?

Anyone else swap them out? What results are you getting?

 

[Odoyle]

Is the new probe fitted properly and tight?

Is the Breech o-ring still there?

Is the barrel TP aligned properly?

 

[Long_Gun_Dallas]

Did you change the port as well? If you did not, the opening on the probe is larger than standard... so when air enters the barrel thru the smaller port opening, it's going to tumble slightly more on the trailing edge of the probe opening.... I port matched mine and picked up 75fps on the factory tune. However, this is a .22 The porting I did becomes more and more minimal as the caliber goes up. As do the gains

 

[MoeHofer]

Its these things I'm talking about. Dont think they are called "probes". Lol

 

[biohazardman]

Looks like you already had a very nicely matched and ported barrel and probe going for you. Nice werq by the way. I went the other way and tried a pin probe on mine instead of the enlarged barrel inlet ports and lost 4fps as like you I had already tuned things up pretty good.

So, did you try a bit more reg pressure and hammer spring with that? That may be the only way to see if it will flow more air with your new barrel inlet or not.

Also ten fps is not much it could be simple like barrel alignment or pellet probe alignment very slightly off which are the same things that Odoyle is talking about.

You only get significant increases in velocity when adding the ported barrel inlets and pellet pin probes when you have a stock gun to start with.

 

[Odoyle]

So these huma aftermarket barrel probes are supposed to increase my velocity on my crown by an average of 30 fps, or so I was told. 

I swapped them out today and actually LOST 10 FPS on my 700 mm barrel. 

What in the world is going on?

Anyone else swap them out? What results are you getting?

 

[Odoyle]

BTW- Lol?

Check your probe not loose and aligned properly.

https://youtu.be/_VNognVDiak

"BTB" syndrome...

 

[TMH]

O.K., if I am now reading this right the O.P. didn't install a new pellet probe, but a Huma dual hole transfer port.

I don't know how to solve his issue, but just to make sure we all know what the change to the rifle was.

 

[MoeHofer]

O.K., if I am now reading this right the O.P. didn't install a new pellet probe, but a Huma dual hole transfer port.

I don't know how to solve his issue, but just to make sure we all know what the change to the rifle was.

That's correct. Thanks!

 

[stoti]

So, you installed a dual transfer port? What probe are you using? Pin probe, modified probe or the standard probe that came with your gun?

Stoti

 

[Jayson]

It very much depends on caliber and tune, in 25 cal it dropped for me also with a moderate tune, helps a little if your flaming, seems to make a little more difference in 22 cal, but valve dwell time and hp vs low will change the results a bit, I still believe that bridge across the middle is disruptive? 

 

[Long_Gun_Dallas]

O.K., if I am now reading this right the O.P. didn't install a new pellet probe, but a Huma dual hole transfer port.

I don't know how to solve his issue, but just to make sure we all know what the change to the rifle was.

That's correct. Thanks!

Ok, so the problem is the opposite of what I stated. Instead of a small opening tumbling across a larger one, you now have a large opening tumbling across a smaller one. The port you have is supposed to have a probe to match the larger opening in it. Of course you can just port match your existing probe, and your issue should be resolved.

The port work I have just smooths airflow. That's the name of the game. Velocity, and laminar flow. I did not actually open the throat at all, as it was already the ideal diameter for optimal velocity of air charge.

It should also be noted that a smooth port finish actually adds a bit or turbulence. That is why mine are not "polished" all the way. I did try polishing just to see, and lost power.