Fx Impact Fix & Mods for more FPS / FPE

I've seen no huge benefits to removing the top half of the probe, in .22 it created chambering issues for me. Double porting gave me 7-10fps slower than removing the top half, but I'm making my own pins that smoke them both lol

@edosan - https://www.airgunnation.com/topic/forum-ux-issue/

I've seen no huge benefits to removing the top half of the probe, in .22 it created chambering issues for me. Double porting gave me 7-10fps slower than removing the top half, but I'm making my own pins that smoke them both lol

@edosan - https://www.airgunnation.com/topic/forum-ux-issue/

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Yep, I find no benefit in double porting vs enlarge and countersink , Ive try the pin, about the same than removing the O ... so when 2 solutions are the same, I will stick with the simpler one. Also test left the pellet in different parts before  after the TP, there is a place that allows about 5mm of difference with no changes on accuracy, so pin shape PP will work with pellets and slugs too.

Hope they (forum mods/admins/tech) fix the problem soon but not sure if is a problem or intentional. Only happens in this thread.

Yeah, with a lathe - it is pretty easy to make a pellet pin and a slug pin (if you really need a dofferent seating depth for the two)! 

Just to confirm. Is this how it should be done to get the best air flow without taking too much out of the probe and having issues with seating pellet and slug inside the chamber.

Just to confirm. Is this how it should be done to get the best air flow without taking too much out of the probe and having issues with seating pellet and slug inside the chamber.

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All my impacts (2), in all the cals (22.25.30) had that mod in the PP, and I have made that mod for other impacts more than 10 times probably + like 20 others just for the probe ... all are fine and working like a Charm. 

And yes, that is one way to remove the O (the simplest imo and the one I use) just polish the edges good, no sharp edges and all good. PP mod goes hand to hand with Brass Port Barrel mod, always both need to be made.

Yeah, with a lathe - it is pretty easy to make a pellet pin and a slug pin (if you really need a dofferent seating depth for the two)!

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Not really need it IME (2 different)

Ok just got done with taking out the O on the probe. I shot over the chrony with 33.9 USB heavy mk2 before the mod and I have 925-930 fps. This is with the elongate brass port and large hole on the probe. After removing the O, I shot over the chrony. With same setting, and got 925-930. In my case I didnt get any increase power from taking out the O. That's just my experience. Maybe others will have better luck. I'm running 25 cal 600mm slug liner with 160 bar huma gen 3 reg and 6g hammer weight. Maybe my gun is max out without an extra plenum. Idk.

Could be, or maybe there is a problem with your brass port enlargement, and you have your restrictor there. Pellet Probe looks ok

Could be, or maybe there is a problem with your brass port enlargement, and you have your restrictor there. Pellet Probe looks ok

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Idk maybe. This is my brass port.

Maybe its getting out of alignment with the damaged to the block pin groove?

The brass port should always be flared and blended in any caliber to cover the 7mm port that feeds it. Seat a pellet first so you know how much room you have to work with and round the short side radius to that point. You can never achieve laminar flow across a 90 degree angle. You won't get complete laminar flow anyway but you want to get closer for best flow and least resistance.

In other words you want a curved ramp leading to the back of the pellet.

@2fast2furious Porting the valve housing, and matching that with the block and transfer port gained me the most airflow and FPS, but it was in the .30 caliber. All the edges were smoothed and/or radiused, and the back of the valve housing port was ramped so the air coming out of the valve seat didn't hit the back wall at a 90° to start it's travel up the ports. The pellet probe is ramped a bit as well, but at this point the air is headed down the barrel anyway so it probably didn't help much. As heavy-impact indicated, air flows better around the raduised corners and it gets turbulent around the 90° square drilled corners.

@2fast2furious Porting the valve housing, and matching that with the block and transfer port gained me the most airflow and FPS, but it was in the .30 caliber. All the edges were smoothed and/or radiused, and the back of the valve housing port was ramped so the air coming out of the valve seat didn't hit the back wall at a 90° to start it's travel up the ports. The pellet probe is ramped a bit as well, but at this point the air is headed down the barrel anyway so it probably didn't help much. As heavy-impact indicated, air flows better around the raduised corners and it gets turbulent around the 90° square drilled corners.

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How can you match the brass port to the block port and valve port. They are inside the block and cant even see where the port holes are line them up with the brass port and probe.

How can you match the brass port to the block port and valve port. They are inside the block and cant even see where the port holes are line them up with the brass port and probe.

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They're already lined up you just flare the smaller one to cover the larger one. The block port is 7mm.

@2fast2furious The block has a decent sized port at 7mm, but it is even better at 8mm! Lining up the block's port hole takes a bit of measuring and marking to get the valve housing matching. A good sharp scribe bent at a 90° would allow you to mark the valve housing's port through the block's hole so you have a reference for cutting/grinding away material. You can look up through the factory drilled 7mm hole in the block to see if the brass transfer port is aligned. 

I ported, polished and lengthened the valve housing first, then opened up the block to match that, then matched the edges of that port to the brass transfer port. All of this work is done with an assortment of Dremel tool bits. It was tricky but with a steady hand it isn't really that bad.

@2fast2furious I read about your jamming, I shoot with both mags and no problems...it might be that you remove too much O?, if you check my pic, mine has "flaps" and you remove that ... check this one, all in 0.25 that I made a few months ago:



0.25 cal O removal on PP and enlargement and countersink on BP

That is how I do it, maybe you took too much O and that is pushing the slug down and you get your jamming. Donno, is something never happend to me (but is key to understand where is the problem). You need to figure why is jamming, could be the brass tp? (I shoot mainly slugs in all cals for hunting and never got a problem with jamming). PP are cheap and you can get those easy FX. BTW is mentioned several times, as an advice: Get the parts before making any mods, so you can go back in case you are not ok with your change.

Yea you still have a bit of round curve on yours. I made mine flat cause I thought it look better that way. When it push the slug though, the mag cycles and the star shape goes into the probe hole and jams. Well time for a new brass and probe.

Yea you still have a bit of round curve on yours. I made mine flat cause I thought it look better that way. When it push the slug though, the mag cycles and the star shape goes into the probe hole and jams. Well time for a new brass and probe.

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they should have

Is there like a table of contents for mods in this thread? Would be a great idea to update the first post with links to posts with relevant info.

Gentlemen, maybe someone can help, trying to buy a slug line .30 liner but in Poland this is not possible. Krale in the netherlands does not have or answer when it will be. Maybe someone can buy me a liner and send it to Poland ?? The cost and payment issue will be discussed at pw.