.25 Impact2 w PP and 700 mm slug liner tuning tips.

I watched this video. I found it very helpful. I’m not sure if it is what most people are doing but I have an impact and I am shooting the Nielsen 29.5g slugs and shooting them around 950fps. Shooting around 1moa at 100yds with a superior liner. 


https://youtu.be/yHP4RCy7Vpg

hope this helps

grant 

I have an impact mk2 25cal 700 with a slug liner but no power plenum yet. But the tune that I have great results was with valve adjuster on the fourth line to the speed i was getting with the nsa 36.2 slugs @930fps. The two things that I did was adjust hst and the regulator @160bar then I started shooting groups @ 75 yards ending up turning the valve back to just over the third line, I stopped there because the group was touching. Now I did I shot over the chrony and the speed @920 FPS and that is fine. When I get my power plenum I will repeat the same process but hopefully with a much lower regulator setting. The gun will tell you what setting it likes by the groups. At the present time I have the power wheel on #4 @820fps and just as accurate as the max setting but I get more shots and the gun overall is more relaxed like I’m not over working the gun. Hope that helps 

I mad a mistake the max setting is not 920 but 910fps .

Please note my gun shoots accurately from lower power wheel to max , but I turned the gun on the max setting with the valve adjuster wide open just to get the most out of the gun then slowly turning down the valve adjuster till the groups tightened to point of touching. Now that I settled on the group the gun slowed down 20 FPS. The power wheel i use from min 1-2-3 for 25 grain pellets 4-5-max for slugs that only change my speed. I believe tuning on max allows the slower speeds to be accurate and consistent. It took me a long time to get it right, that was about 8000-10000 shots ago. When I get my power plenum it may take me several hundred shots and a lot of adjustments to the regulator, hst and valve adjuster. I hope that this is more clear.

A while back a guy had received a impact mk2 25cal pp and slug liner 700 like your gun and if my memory is correct his regulator was set at 138bar And turned down his valve adjuster around the third line also, but keep in mind at this point you’re shooting groups to know when you’re there. Now adjusting the hst is very important to get the most speeds right and consistent from the start. Hopefully this information will give you a better idea where to start. Good luck and I’m interested in the results.

This is my same gun set up and I have mine dialed in as follows: 

Reg@ 150 bar

HST(at MAX)screwed in all the way then backed out slightly so the wheel can move freely.(do this while the gun is uncocked)

Valve adjuster at 3 1/2(started at 4)

One ragged hole at 50 yds with NSA 33.5gr slugs averaging 920fps.

Remember to listen to your gun, chronograph and your gut. You should be fine. 

Hope this helps you

Also I used the MK 2 heavies to get up to 940ish then settled it down to 920 with NSA to save on my slugs. Have a great weekend!