Tuning Impact mk2 and the "ER Port"

[dannya1a]

had some time today to do some tuning and seeing what the ER port has to offer. Man this TP from Ernest is a monster. So I had my reg set at 125 bar and was slinging 26.8 gr NSA's well over 1000 FPS. Cranked down about two turns on my hammer. Couldn't get it much below 1008 fps. Dropped my reg pressure down to 115 bar or so. Reg gauge is pretty jumpy. (gonna have to get a better gauge for that.) so now its 995 fps average. with hammer adjuster on 3. Nice. group test at 30 yards is stacking and consistent.

So now time to test the other side of the "ER port". flip the barrel 180* and load in some 29.2 gr NOE hunters. 890 Fps over the chrony with no other adjustment made. Now that makes me happy. All I'll have to do is adjust windage back and forth for the two rounds as they were pretty close to each other. once i get to that point I'll probably need more fine tuning work. but as a quick base line test. I'm very happy with the "ER port". I figured I'd need to open the low side of the port as it seemed pretty small for .25 cal. but its seems perfect at the moment.

Current tune on the 700mm Impact MK2

115 bar on reg

power wheel on 3

20.28 mm on HST

and 6.36 mm on valve adjuster

 

[stoti]

26.8 gr are pretty light. Try leaving your gun set up using the larger port and just using either the power wheel or valve adjuster to increase, decrease and tune. It will save you having to mess with the barrel. That depends if you switch projectiles often I guess. My opinion is that you can never have too much air flow through the TP. You can always use the valve adjuster or wheel to decrease velocity if necessary. Have fun! Have a good one.

Stoti

One other thing, when tuning the gun, the least amount of hammer spring you can get away with and still fully open the valve the better. Your shot cycle will be a lot less “harsh” therefore less worrying about harmonics. Many of us tuned on max for all the power we could get for heavy slugs...Super harsh!

My gun is at 110bar shooting the 33.95 @920fps with a super smooth cycle. I just did it yesterday and can’t remember exactly but I think the valve is on 3 lines and HS preload like half way. My power wheel is on max.

 

[Eddy1840]

had some time today to do some tuning and seeing what the ER port has to offer. Man this TP from Ernest is a monster. So I had my reg set at 125 bar and was slinging 26.8 gr NSA's well over 1000 FPS. Cranked down about two turns on my hammer. Couldn't get it much below 1008 fps. Dropped my reg pressure down to 115 bar or so. Reg gauge is pretty jumpy. (gonna have to get a better gauge for that.) so now its 995 fps average. with hammer adjuster on 3. Nice. group test at 30 yards is stacking and consistent.

So now time to test the other side of the "ER port". flip the barrel 180* and load in some 29.2 gr NOE hunters. 890 Fps over the chrony with no other adjustment made. Now that makes me happy. All I'll have to do is adjust windage back and forth for the two rounds as they were pretty close to each other. once i get to that point I'll probably need more fine tuning work. but as a quick base line test. I'm very happy with the "ER port". I figured I'd need to open the low side of the port as it seemed pretty small for .25 cal. but its seems perfect at the moment.

Current tune on the 700mm Impact MK2

115 bar on reg

power wheel on 3

20.28 mm on HST

and 6.36 mm on valve adjuster

What caliber are you using? I went to New England Airguns today and got all this

I’m just waiting for my 700mm superior barrel to come.

 

[dannya1a]

.25 cal.

Stoti:

thanks for the valve reminder. I didn't give it too much thought. I just dialed down the hammer tension. didn't give me enough. so I moved to dialing down the regulator. I never once touched the valve from where it was set. I knew that that gun was previously happy at the power wheel 3 setting so i just started dialing that down to get back down where i was hoping to. My goal was 950 FPS with the 26.8 gr NSA's. I definitely need to put more fine tuning into the setup. But things look really good currently. the slugs and pellets are both stacking well at 30 yards. This slug A liner that I picked up has been really consistent thus far.

 

[stoti]

Some people, lots actually, never even bother messing with the valve adjuster but you can fine tune it to really decrease your ES. Just trying to give you some things to think about. I also run the Slug A liner. It loves the 33.95 MKII’s but Centercut prefers the MKI’s in his slug A liner. I’m going to try them again. The slug A liner also loves the 32.8gr and 34gr Varmint Knocker slugs. They have almost the same POI as the 33.95 gr. pellets out to 75 yds. which is vert handy. I’ve heard others talk about various NSA slugs but I tried them all up to the. 38.5 gr and never had any perform like the Varmint Knockers. There are so many subtleties with tuning these guns and differences in liners that you really should try things yourself to know for sure. Have a great weekend. 

Stoti

 

[dannya1a]

I'm sure. I know when I first re-did the tune on my gun, I had set it with it on max power wheel setting, the valve adjuster was wide open and used the hst to adjust the speed where I wanted it. 

The second time I set it with the power wheel on minimum as I was after a specific speed for pellets, then I rechecked where it put me for the Max power wheel. Maybe today if the winds die off and it warms up a bit. I may try and get a proper tune into it, by doing things the correct way and seeing what I get. I know it needs more work as my ES and SD are about double what I did have. Even at double I'm still in the single digits yet on the high side of them.

 

[triggertreat]

If you are using the slug kit, the valve knob can go in quite a bit before you see a significant change in velocities or ES results. I find a PW setting of 3 or 4 works best no matter what I am tuning for. With a slug kit in mine and using both hammer weights, I find my ES still low and still see a lot of duplicates on the chrono, but it isn't quite as tight as when I didn't have the slug kit installed. It will still put out a very tight ES though when I get the tune balanced out well. A big part of that is getting the valve knob set correctly.

I'll list my current settings. I'm not saying it's my best tune, but one I have used for a couple of weeks without feeling the need to adjust it. I do have the PP as well as the slug kit, and am using a Huma dual port. This tune is shared between my .30 700mm and my .25 cal 600mm, but primarily for the .30 cal launching the 47gr cast in the mid 900's.

Reg = 130 bar

PW = 4 (HS gap 19.6mm)

Valve knob is just slightly past 1 with a gap of 6.85mm

I know I can drop the reg down more, but I am afraid of changing the valve dwell too much and increasing the ES overall. I really like seeing the duplicates come across. I will still try lowering the reg to see though for sure coming up.