Tuning Imapct MKII losing speed, HELP please

[RafaRM]

Hi there, My FX Impact MKII is gradualy losing speed and has nothing to do with the regulator as the pressure remains stable, also no leaks anywhere. If I tighten the hammer spring I get again the FPS but after a few shots then FPS go down again.

Any hints on this? Can it be the hammer spring losing tension?

Thanks in advance for your help!!!

 

[Vetmx]

I recently had the same problem. Wounded an animal so I checked my gun and it was slow. Checked the hammer spring measurements I had recorded in my notes and my hammer setting was way off. Turned the hex screw until I got my proper measurement back and all was fine. This time I dabbed some blue lock-tite on the screw. Hopefully this will stop it from happening again.

 

[capefeargunr]

Hammer seat might be loose or C3 bumper going bad. Degas the gun, remove the valve stop adjuster assembly and check both.

 

[dannya1a]

Since its a MK2 impact... Its either going to the the C1 under the valve is working its way loose, or the little grub screw for the hammer spring tension the rides the power wheel is backing itself out.

 

[RafaRM]

Thank you. It should be something external as the micro hex adjustment stays in place. I took it a couple of weeks ago to the FX offical repair and they changed the front spring that closes the valve, but the problem continued. I sent it back to FX yesterday, hopefully they solve it but I will talk to them regarding your hints.

Thanks again!!!

 

[Ratrider]

I have a MK2 impact and had the exact problem. Velocity going all over the place. I found it was the grub screw in the hammer spring slide working loose at each shot. In the end I had a machinest friend build another custom slide but with a 2mm locking grub screw 90 deg to the horizontal main grub screw. The new main grub screw is 22mm in length. Seethe photos. This eliminates the need for any locktite. Particularly if you want to adjust anything. Every MK2 should have one.

 

[Vetmx]

Absolutely. I can’t believe for all the years these guns have been out that someone wouldn’t market a product that keeps that screw from migrating. It’s the dumbest thing I ever saw on a high end gun. It only took FX six years to finally address it on the M3. I’ve been debating several ideas for my gun.

 

[qball]

A drop of lightest Loctite mitigates the issue. 

 

[dannya1a]

I use Vibra tite vc-3 on mine and the issue doesn't happen anymore. I also have the custom prototype grub screw in mine that fx sent me. It has a special end on the grub screw to give it more bite against the power wheel. But I have also since move to the Monster power wheel. 

 

[Keyman62421]

In all the years FX hasn't corrected their design flaw! 1 of many!

 

[Vetmx]

A drop of lightest Loctite mitigates the issue.

That’s what I’ve been doing since this poor design first bit me. I just can’t rationalize basically using glue on something that you might need to frequently adjust. It’s dumb but they finally fixed it with the newest gun.