Lets talk about transfer ports…
I have noticed that Crickets (and probably other guns as well) seem to have different size transfer ports. The cricket has 3 TP’s as far as I am aware of. One in the barrel, one in the breech block and one in the valve. How come they are not the same size? Would it not be optimal for performance if the were equally sized?
Just as an example we will take a look at Octavius .22 Cricket.
Valve: 4,35mm
Barrel: 4,02mm
Breech: 5,06mm
Surely it would be better if the were equal? Say just as an example 4,5mm, like this:
Valve: 4,5mm
Barrel: 4,5mm
Breech: 4,5mm
Does anyone have something to say about this?
All Replies
I don’t think that is necessary, is it not for high powers? I heard it is not needed unless you have a high power .25 but that info might be incorrect. Mine is just .177
If needed you can make the barrel port oval but unless you shoot bullets it’s unlikely that you really need to do that.
I have a leak inside the regulator…. The “tell-tale” hole is telling me this. Unfortunately that means disassembling the regulator so I am back to Square one… Oh well, further tests will have to wait until I have sorted out the leak. But if you enlarge the barrel TP make sure to follow the rule
What I did was:
1. Clean the barrel
2. Run some pellets through with a rod of some sorts, make sure not to damage barrel. (I wrapped my rod in electrical tape)
3. Enlarge TP.
4. Polish TP, no Sharp edges.
5. Run some pellets through like in step 2. Compare these pellets with the old ones and make sure they are not more damaged.
80% of 4,5mm is 3,6mm so I took a 3,5mm drill bit and drilled the hole bigger. I used the rod inside the barrel to protect the inside of the barrel. The pellets Before and after were identical to my Eyes so I have my hopes up 😀
Yes. I’m not familiar with Crickets but usually biggest power losses take place inside the valve housing as that has a 90 degree bend in the air channel and that is usually made by drilling two holes in 90 degree angle. Make that angle smooth and round and ensure that all flow areas in the air path are matched with valve throat being 10% bigger than the rest.
Good morning octavius, I am going to resume the tuning today, I also got my new scope and scope rings so I can do some accuracy once I am happy about the chrony results.
All I did was drill the barrel tp bigger and then polish off the rough edges. That is why I do not want to brag about it just yet. Yes, I reached 285mps or so with heavy wich is my goal but once again I might have ruined my barrel… but I don’t think so 
I will post in this thread later today (hopefully) and I will also make my own thread in the kalibr section about my rifle. It is looking pretty neat at the moment…
Something like this ? https://m.youtube.com/watch?v=eLDhUyDx-8M
And round up the bend from valve tunnel to valve housing exit with dremel, that should give you some 20-40 fps extra.
Thx for info Cricket :8: & rkr.
What do you want to know? Open up the valve housing exit diameter to match the breech, make the barrel port conical to meet the breech port diameter at the bottom. Check the valve tunnel minus valve stem area to be valve housing exit area + 10%. That will get you the max power based on existing barrel port diameter.
I enlarged my tp with great results octavius! :biggrinn: :biggrinn: :biggrinn:
I am tuning it right now but it is getting late over here so I will continue tomorrow. When I am done and have tested the accuracy I will come back and tell you exactly what I did. But I must make sure about the accuracy first in case I ruined the barrel without knowing it…
Any informations? 😉
Yes, I have a .177 able of 860 fps with 10,34gr pellets. However the optimal speed for this pellet in this caliber is around 930 fps.
So please give us some info, all brands and calibers are welcome, just gives a wider perspective of it.
Hi Guys, myself and Cricket we are not power hungry guys. We wants only same speed possibility setting as many others cricket owners. For example my cricket only does 895fps with regulator pressure set to 140bar!! Why other guys get same or more speed with regulator setting to 125bar!!!
Can someone else measure your transfer ports please? What we know are only my and Cricket… If we found correct dimension we can slightly enlarge them with a dremell or so…
You can’t make a round barrel port much bigger than 75-80% of caliber or it starts damaging pellets. Change in channel size introduces a sharp lip which is bad for airflow. Ideally the port should have no transition in size or be conical if transition is needed. Still, I bet the biggest hit for the flow can be found inside the valve housing, that 90 degree turn is usually the biggest problem.
I don’t know what that BS about too big TP sizes is, you can get very good air efficiency and nice power curves with big TPs.
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Allright, the leak inside my regulator is fixed and I am getting Close to my goal. I shot one Magazine (14 shots) through the Air Chrony just now. 2mps with avg speed 284mps
So I’m going to pump it up and play around with the HST to see if I can fine tune it a bit and when/if I’m happy I’ll do a full shot string.