Impact mk1 vs mk2.

For $150 you can give your MKI 30% more power than a stock MKII. This will give about 70 fpe in .22 cal and 120 fpe in .30 cal with a 700mm barrel.

1: Buy the big air tube that I designed 4-25-19 from Michal in Poland $140 shipped. He copied my design from this forum.

2: drill your valve seat to 1/4".

3: Elongate your brass pellet inlet and remove the top half of the probe.

Everything will still feed and function as well as unmodified when the porting is done correctly.

The guy in Poland is swamped with orders so he's hard to get in touch with and then takes about a month to deliver.

Never make the brass port wider, remove the top of the probe instead of the bottom and be sure not to cut past the midpoint on the probe. Don't make the port too long or you end up with a 90 degree wall at the end of the liner. You want a radius there to let the air transition as smoothly as possible.

The brass port on Impacts is about 90% the width of caliber which leaves 5% bearing surface on each side of the slug to hold it inline as it spans the port. This is why making the port even a tiny bit wider causes feeding problems.





[email protected] Tel. 883999733 dial with international prefix +48 (Poland) He's been swamped with orders so expect 30 days or more for your order.

http://www.airguntuning.pl

Pictures of my plenum design produced in Poland.

MKII isn't much of an upgrade... maybe 15 fps. Check the time difference and try calling Michal around 9am his time.

I'm surprised there aren't more sources for these plenum tubes, since it's such an obvious idea. FX should have been the first to offer them. I'm sort of holding out to see if their eventual .35 cal has something like this. 

There is several versions of the impact. "mk1" is not simply "mk1". Think Matt dubber explained in one of his videos that there is small changes or improvements along the line. Some are probably not noticable by the user, while others are. Think the mk2 also was the first version which had a 600mm barrel as standard in .22 caliber (I could be wrong though), while the older ones had a 500mm barrel. 

Need to get a group order. 

Got hold of him. He said $100 plus shipping $55. Wow $55 just to ship a small package. A small bubble envelop to ship it in would cost like $3 to $5 max in the US. I guess shipping from where he lives is expensive. Did you compare the larger plenum to the stock with same setting and see how much fps/fpe the larger plenum gives.

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I learned when ordering mine that shipping is very complicated in Poland. Michal's shop seems to be a long distance from any package carriers so some weird service collects packages and warehouses them for a couple of weeks before transferring them to Fedex. I hate waiting for anything but this seems to be his only choice and he packages them well. You will get a Fedex tracking number only after Fedex takes the package so don't worry.

Even at $155 this is the best mod you can do to an Impact. The $100 price is low anyway for the labor involved. You'll be smiling once you install it.

My gun has a 20cc external plenum and the mods listed above also but I would say 20 to 25fpe in .30 cal with a 700mm barrel. I didn't test the eccentric plenum alone.

During initial testing at 150 bar I got 1072 fps with 50gn jsb pellet and 948 fps with 66gn nsa fbhp.

.How much fps with 50gr did you get with stock fx plenum before you install his plenum. I know you mod your impact with with transfer port, probe, hammer weight etc. But if you test fx stock plenum and michal plenum with same mods, then all the mods would cancel itself out. I just wanna to see how much difference in power/speed vs fx plenum so I can justify spending the $155 for the upgrade.

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My previous best was at 170 bar. Now it's a little over 100 fps faster on 150 bar.

You considered a $400 MKII upgrade that nets almost nothing. This upgrade is MKII x 15 but costs 2.5 x less so I don't understand your line of thought.

Great info