Evanix Sniper X2 .45 project

[rkr]

You will find all the O-ring specs and tolerances online, and there is your dimensions to start by. 12mm poppet, 11mm bore, 9mm balancer piston, 5mm stroke.
Its called testing and development what goes to making it work.

Why limit? Why have a hobby at all? I make the guns for the fun of making them, I have invested money to have industrial grade cnc machine shop equipment to make what I want. Guns, cars, turbos, you name it. Why because I can!
And I do have some powder burners too but air is more interesting. Besides there is no way and no how I could get a permit for 20mm rifle if it was not an airgun.
Sorry Riku for the OT

Marko

No worries, you posted good reference data. 0.5mm seal width, 2/3rds of the valve tunnel area for the balance piston and 5mm strike length are easily transferred to what ever size one needs. I was considering 50% area but for this gun I might just as well go for 66%. 5mm strike sounds a bit short, tracing back this thread I saw an increase in power when I went from 5.5mm to 7.5mm strike. Of course that is mostly caused by increase in dwell which should be greater anyway with balanced valve so 5mm may well be enough.

[MJP]

5mm valve stroke, not hammer travel.

[rkr]

Digging up an old project. I had big problems in getting the firing valve to seal. The problem turned out to be the Ertalyte that I used to make my poppets, it was brittle. While chasing the problem I ended up making a new valve block for the gun using 2mm valve stem. That one drilled through the poppet at first go so I eventually made the poppet from normal POM and used a grub screw at the back of it to stop the stem from pushing through. That setup finally held air but I got tired of the project and got interested in powder burners so the gun went to gun safe and stayed there for several years.

I have since managed to source a 28" TJs barrel for this gun and I'll be installing that one next. When I dug the gun out of safe it was still holding that 150 bar that I left in the gun and it fired without leaks so looks like leaks are sorted. The goal is to use MP molds collar buttons (153 grains) and have them shoot around 850 fps or more (250 fpe). Finding a mold for light bullets in .458 was a nightmare, the best I could come up with was this collar button design - I hope it works well enough.

To start with I cast some bullets to test things with, they dropped at 11.73mm which is 0.4618 for those metric challenged. Next task was to slug the barrel, that turns out to be 11.635mm or 0.4581 -TJ states .456 so it was indeed a good idea to slug it. I have a .454 Lee sizing die so the next task is to hone it out to 11.62mm so I get proper size bullets to make the breech side of the barrel. People usually recommend same size or slightly over dies but I have had good results with 0.01-0.02mm under so that will be the starting point.

The barrel is a bit rough, I'm considering using a pull through and some polishing paste to smooth it out. My goal for this gun is 2 MOA accuracy as those bullets are not meant for precision shooting so I'm not exactly sure if I need to polish the barrel. Some shiny bullets:

IMG20250513124424 by abbababbaccc, on Flickr
IMG20250513124750 by abbababbaccc, on Flickr

[YEMX]

VERY nice!  I'm glad to see this old project resurrected! 

[rkr]

Some more progress, taking it slowly. The bullet sizing die was honed out, it turned out 0.015 mm oval but it was that much oval when I started so I guess I'll live with it. With properly sized bullets I was able to start measuring and making the breech end of the barrel. I decided to use a thimble approach as it allows more precision, first I reamed out the breech end of the barrel with 1:50 reamer, just enough to make the bullet slide in all the way while leaving slight rifling marks on the nose.

4202025125555 by abbababbaccc, on Flickr

Then I made the actual thimble, I didn't have big enough piece of brass so I used steel. In these big bore evanixes the TP is IMO too far back in the breech forced by the valve nose. When you drill it out it moves even further back and the o-ring inside the barrel gets compromised. In my gun the TP was drilled out to 9mm by previous owner and the o-ring was partly open to barrel port, not an ideal situation. To fix this I machined the barrel port at 35 degrees angle forward, this gives me 3.0mm inside the barrel in between the barrel port and thimble end - enough for o-ring that I plan to move to the probe.

4202025125613 by abbababbaccc, on Flickr

Next barrel attachment where I have a new trick and then the probe. After that power adjustment and eventually accuracy testing.

[rkr]

Probe with o-ring + all the little parts from the breech. The probe looked so bad after previous owner had messed with it that I considered making a new one, it turned out half decent after some fixing.

4212025125236 by abbababbaccc, on Flickr

[rkr]

Got the barrel fixed, filled the air tank, started testing and I remembered what a PITA a Chrony is to use. Finally third shot gave me 450ish fpe reading so I turned the adjuster 4 turns in. Then nothing worked, fifth shot registered at 912 fps and I had 150 bar left in the bottle. That's 270 fpe so I could turn down the power a bit. I really should do a shot string but that "dang" chrony is eating me up. I shoot in the garage and have led spots above the sensors - everything need to be aligned just perfectly or I get just errors. I'll take some photos when this rain stops.