Tuning Impact tuning question

[Corvid_hunter]

Is it possible to tune a new Impact .25cal (with 700mm Superior liner) to shoot 25gr JSB pellets at around 875-900fps while set on Min and turn it to Max to shoot some type of slug equally as well? IE, one tune that would shoot both accurately as opposed to having to change settings between pellets and slugs.

 

[8thman]

Yes, that’s what a lot of impact owners do. You can tune it shoot the desired slugs on max and when shooting pellets turn down your power wheel to the speed that you settle on.

 

[ghostrider0311]

Is it possible to tune a new Impact .25cal (with 700mm Superior liner) to shoot 25gr JSB pellets at around 875-900fps while set on Min and turn it to Max to shoot some type of slug equally as well? IE, one tune that would shoot both accurately as opposed to having to change settings between pellets and slugs.

Yes very possible

 

[golfer70]

That’s exactly what I do. I also mark my turrets with red numbers for slug yardages and blue numbers for pellets. A quick turn of the PW and VA and I can easily switch back and for when at the farm. 

 

[dannya1a]

i have my minimum pw set for 29.2 gr NOE hunter pellets. the with "ER transfer port", flip over to wide open and run slugs on PW 3-4 depending on my speed. with 26.8 gr NSA slugs they are moving at around 1032 FPS on max.

 

[qball]

Is it possible to tune a new Impact .25cal (with 700mm Superior liner) to shoot 25gr JSB pellets at around 875-900fps while set on Min and turn it to Max to shoot some type of slug equally as well? IE, one tune that would shoot both accurately as opposed to having to change settings between pellets and slugs.

it’s especially easy with the 700mm barrel. 

 

[stoti]

I agree with these guys 100%. I just wanted to add, depending on the pellet and slug choice, you might be able to shoot them both with the exact same tune, no changes at all. This isn’t my set up anymore because I switched slugs and my son Cooper is using this scope, but for a while I was shooting the 33.95gr JSB’s and the 32.80gr Varmint Knockers with the same tune. The POI was almost identical at 65yds and then as yardages increased, I just marked different yardages on the turret for the two different projectiles. The orange are for pellets and the blue for slugs. It made shooting either of them very fast and easy.

Have a good one. 

Stoti

 

[biohazardman]

Like Stoti said I was shooting both the .25 JSB 33.5 pellets and the NSA 33.5, 36 and 36.2 slugs on the exact same tune. They were both shooting MOA or better at 50 yards and the slugs were still there for the most part at 100 yards. That was with the 700mm slug A liner in .25 though. I expect that other liners will do the same.

Scroll down for targets.

https://www.airgunnation.com/topic/installed-my-new-700mm-slug-liner-on-my-impact-and-started-tuning/#post-535484

 

[cgun]

Hello all,

I am new here, but have been lurking for a while. been getting a wealth of information so when I finally got my impact, I would understand how to tune it properly. between here and Ernest Rowe, I got a wealth of knowledge. So, I got my FX Impact, 700mm in .25 with the power plenum and I also upgraded to the Huma high flow dual port and the FX Slug power kit. To answer the OPs adjustability setting, my current tune is

Nielsen 33.5 grain slug - regulator at 138bar - hammer spring probably has about 3/32" of slop at max - valve adjuster is at 2.75 lines 

I am getting:

Max: 980fps

5: 925fps

4: 875fps

3: 830fps

2: 775fps

1: 715fps

Min: 675fps

This should give you some idea of how you can adjust the tune just using the power wheel. My setup gained a huge amount of adjustability when I added the High Flow Port and the Slug Power kit. I could probably push these 33.5 nielsens over the speed of sound if I bumped the reg up to 155bar, maxed out the hammer and opened the valve adjuster. I don't need to though. The gun is ridiculously quiet at this power level with the DonnyFL FX Moderator on it. all you can hear is the valve being hit and the reg refilling, and a split second later the loud slap as the bullet passes through the 1" pine backstop. 

I also have a 45 grain slug based off the Huben design that fits in the FX magazine and I can push those with this tune to about 915 on max for about 83 ft-lbs. Again, I could probably get them up to 1000fps is I wanted to really push the gun, but it is unnecessary. 

I just wanted to let you know that once all the tuning that requires tools is done, the gun is still highly adjustable just with the power wheel and valve setting.

 

[Corvid_hunter]

Thanks for all the replys gentlemen. You have definitely made my decision easier.

 

[Drumsnguns]

CGUN, are you using the Power Kit light valve spring here? Are you shooting the 33.5's at 980 on MAX?

I tried the light valve spring at first but wow was I getting super high velocities. Went back to the heavier OEM valve spring.

I'm having trouble grouping right now at 150 Bar shooting 33.5 NSA's at 960 fps for sub MOA to MOA groups at 50 yards but terrible 2-3" groups at 100 yards.

So perhaps I should try the lighter valve spring at lower reg settings?

I'm using the 57 mm spring and Huma Dual TP and FX pin probe.

Thanks

 

[cgun]

I did use the light spring that came with the kit. Here are my settings:

After I installed the high flow port and the slug kit, the gun was still setup for my original tune of the same 33.5 NSA at 940. Hammer was maxed and valve was at 3.5. First shot was 1015fps. I backed the hammer down until the velocity started to drop. I kept it right at the dropoff point then started turning the valve adjuster in firing 3 to 4 times between changes to let it settle. Valve dropoff point was where you see it in the pic above. I am very happy with this gun. It is sighted for 50 yards right now. But it is hole in hole at that distance. Practically speaking MOA is more than sufficient for me to take small game at any ranges it would be ethical for me to take them at.

 

[Drumsnguns]

Good info there Cgun. What liner are u using?

Stoti, I’m assuming you are using the Slug Liner A?

 

[cgun]

I am using the standard liner that came with my gun. I am pretty sure the new ones ship with the superior liner, but don't quote me on that. I am assuming it is the pellet liner though, but it seems to shoot these slugs just fine.

 

[Drumsnguns]

I got my MK2 in Feb. 2020 about a month to 1.5 month before the Superior liners shipped. 
it’s always been about timing w me. 
Ive got the Superior Heavy in mine now and am working w both 33.5 and 38.5. 
Just got the 38.5 and will see how it does. I’m thinking the Superior Liner would be better for 33.5’s