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Tuning My trip down the rabbit hole with Gen1 impact modding.

First thing I did was to port the barrel and probe. Not too big and a bit oval shaped or you will have problems when chambering a round.

Make sure the probe and port are aligned.


Next I added a 1.25mm brass shim/spacer/washer to the inside of the hammer under the spring to get a bit more hammer weight and spring power.

Yes, I know that is not a solid brass 1.25mm shim or the stock plastic spring guide but it is the only pic I have with a shim and hammer in it

Then I had to turn out my Hammer spring Allen screw out several full turns to make the adjusting wheel useful again.

Next I cut the valve spring about two inches and bent the end in. Now it sits on the top of the valve pin

Can't remember whose pic this is but thanks anyway.

After that I made myself a Yong Heng plenum.


Next I drilled a hole in my valve housing so the air from the plenum could get into the gun. Two holes intersecting each other would have been better although most just remove the whole support leg here.

Then I got another valve seal/seat, off of eBay, but had trouble on the install as it cut the o-rings many times. So finally ended up just drilling mine out to 6.1mm which is a bit conservative but I did not want any problems later on. I cleaned it up good and polished the edges with a drill and some 600 grit sandpaper.

I shot it this way for a while then found the polish plenum from Michal.


The gun is shooting the NSA .25 36.2 slugs at 85fpe with the reg set at 135bar but I have it tuned to 74fpe for better shot count and a slight increase in accuracy.

So, I tried the FX Slug Power Kit and found it to be mostly a big mess for Gen1 guns unless you have the Huma Dual Port Transfer Port installed. Although I did manage to move the valve spring to the outside of the gun which will allow me a much greater ability to tune from .177 to .30 cal.

Found the need to drill out the threaded valve adjuster screw and valvestop to fit the new spring from the Power Kit. Screwed it up first try trying to use Ernest's drill sizes. Went smaller, on the drill bit the second time, it still fit the spring fine.


Last but not least although it was already shooting lights out I decided to stiffen up the barrel a bit.


And that is where it will stay as I am in the long long M3 line at this time.

Oops guess I lied again! ;^) I found the rear block had a problem with the barrel indexing pin. FX warrantied the part. I drilled and tapped it for a second barrel retaining screw then slotted the cheeckpiece so i could get at the screw when needed.

I was looking around for something that was the right size that I could use for a plenum and ran into a post from ? I don't remember but he had done it to his Impact. Ah, I found it it was heavy-impact's post. So, thought it was a wonderful idea as I had an extra Yong Heng filter laying around. Timing is everything.
My gen 1 has been fun so far. I've added a power plenum, STX barrel kit, and upgraded to the Superior liner. I've torn the entire gun apart, put it back together, and replaced virtually every O-Ring just for chuckles and grins. It's been well worth the princely sum I paid for it used a few years ago, just in education and fun. Shoots great when I don't have it torn apart too.

I only run it at about 3000 PSI max because I use the 88ci tanks with the Ninja regulator set at 3000 PSI, so second regulator doesn't impact me much. Just bought an MKII about 2 months before the MK3 came out. Bad timing, but I have it in hand and so far, works well and my intent is to never touch the internals unless I absolutely have to. That's what the Gen 1 is for.

Just got the Gen1 back together and am considering Dubber's power kit. My goal is to reduce the regulator pressure as much as possible to take as much stress off the gun as possible. So far the Power Plenum allowed me to reduce from 145 bar to about 110 bar. I'm hearing the Power Kit will allow me to reduce the reg pressure a touch more. If I could find another Gen 1 for a decent price, I'd buy it, but it'd have to be low enough to justify, and I just don't see those lately. Prices still way too high.