Tuning HELP !! What am I doing wrong?

[Gibbs]

I have a .22 Impact mkll compact with factory PP. I'm shooting Hades 15.86 grain pellets. My reg. pressure is set at 100 bar hammer spring is in almost all of the way and valve adjuster is about halfway between the 2nd and 3rd line. When I shoot through the chrony with power wheel set on max, I get just over 1000 fps which I like....but I have to go clear to minimum setting to get down to 970 fps. All settings on the power wheel have little effect to lower fps. Even on setting 3 I'm still at 1000 fps. What do I need to adjust to get more fps spread between max. setting and min. setting on power wheel? When I adjust the valve adjuster in it helps a bit and maybe I just need to keep going with it. When I adjust hammer spring tension it doesn't seem to make much difference, maybe it is too tight?

Any and all suggestions would be greatly appreciated, I could just take it over to UAG but I want to be able to do this myself. Thanks!

 

[ackc1234]

I'm not an impact guy... But sounds like you have way to much hammer spring tension.... Back that way off and try again.

 

[douger]

turn reg to 80 /90 bar then set valve to 4 lines power wheel on max then tune hammer spring to say 940 as 1000 is way to fast then use valve to tune down to id say 920 see how that works if speed drops while adjusting hammer spring up the reg also i think 18 gr would be a better choice regs to high for sure 

 

[qball]

100 is very high for 16 grain pellets, try turn it down to 80 or even 70 then try. Watch the master class video from Ernest row by open hour valve all the way then find a speed that’s 40 FPS higher than your desired speed then crank down the valve. 


for reference my regulator is at 100 and in 22 I was shooting 23 grain slugs at 980fps with hammer spring not even all the way up. In 25 I’m shouting 26 grain slugs at 970fps with just a little bit more hammer spring. MK2 with PP got some serious power and your gun is tuned way too hot for the pellet if you ask me. 

 

[Glem.Chally]

I think you need way less preload on the hammer and lowering the reg a bit would help things. I dont suggest going below 85 on the reg to avoid issues though.

 

[Odoyle]

90 bar reg sounds like a good place to start.

The C3 bumper won't allow much lower adjustment so the reg pressure must go down..

 

[dc8cappie]

My Impact MK2 PP is set a 82.5 bar, tuner knob 8.08mm (3rd line), hammer spring @ 17.58mm (any more tension speed decreases) PW Max, speed 947.7FPS. Any increase is speed will require higher regulator pressure. Hope this helps.

 

[Gibbs]

Thanks for all the great input!

Looks like I need to back off the hammer spring and lower reg pressure a little. Maybe think about a heavier pellet.

My son got a 580cc bottle for his gun so I bought his 480 and put it on my compact, lots of shots from a full bottle of air, sounds like I will be getting a lot more when I tune the gun down a bit more.

Thanks Again for the help!

 

[Healthservices]

Currently I use:

Jsb 18.3 gr exact heavy, inexpensive, affordable, accurate.



Or the h&n hollow points 18.21 gr if you need a hollow point

 

[FelixS]

A heavier projectile will slow it down. This will give you the range you desire.

 

[Gibbs]

I backed off the hammer spring and that seemed to solve all the problem. Tweaked the valve adjuster a bit noting changes in velocity on the chrony.

I didn't want to lower my regulator so it is still at 100 bar. Now I have about 150 fps spread between max setting and min setting on power wheel. Now to a target for accuracy.

Thanks again for the help!

 

[UncleHoot]

Concur with all above. 

My personal thoughts: too much gun shooting too light a pellet. Get your projectile weight up to 18 - 21gr, and let the gun stretch it's legs with some serious lead.

Hades pellets are over priced, in my humble opinion. I have been using the less expensive H & N Barracuda Hunter Extreme pellets, which have a closely related head design, and knock the living hell out of the pests I shoot with them.

Check this web site out for no shipping cost and very cost effective prices on brand name pellets: https://www.fieldsupply.com/airguns/ammo.html  Their supplies vary in caliber, but sometimes you get lucky and find a bargain to be had!



Kindly 'Ol Uncle Hoot