FX Impact loss of power - Probe O'ring...

[tghaines]

Hi Everyone,

Loving the forum and loving my FX Impact.

1. I had my Impact tuned for exactly 900 fps with .22 JSB 18.13 pellets. Over a 2 week break, I seem to have lost 100 fps with the same settings giving me around 800 fps.
I've been reading the forums and it seems that "9 times out of 10" this is due to the pellet probe o-ring. I have no problems changing this if it's what we all think the main cause is......thoughts or any other causes?

2. My next question is on the o-ring itself. My FX Royalle loved the harder 90 den o-rings. Once I changes to them, it was perfect and still have the same ring in there now. Is there a consensus on the 70 or 90 hardness o-rings.

3. when storing your FX impacts, do you keep the air cylinder in place or not? I assume that because the Impacts are shipped with the bottle detached, that it isn't a problem.

thanks,

Trent

 

[Utahairgun]

The oring hardness depends on the part sometimes. The power issue can be a couple different things. With it being so new I think it may be as simple as your regulator breaking in and changing pressure a little bit or the valve spring softening up a little bit. Check your reg pressure again it can change velocity even if it changes 5 bar. I would change the breach o ring first if the reg pressure isn't different but one of the biggest problems we have seen with impacts losing velocity has actually been a part on the cocking linkage coming loose and causing the reg to get short stroked. I would also try turning out your valve spring and see if you can get it back up to 900fps again but if it keeps losing power send it in to get worked on. 

Hope that helps.

 

[tghaines]

Thanks Utahairgun,

The reg pressure looks about the same at 140 (or a needles width under 150), so I think that's ok.

I'll take a look over the cocking linkage and see if anything is loose. Nothing is rattling, but good tip anyway.

I have no problems re-adjusting it again. The adjust ability of the gun is one of the main reasons I bought it. It's just funny its dropped without my intervention.

Thanks again, Trent.

 

[Utahairgun]

You won't hear it rattle nor see it very easily unless you know how long it's supposed to be, if it comes down to having to check that out I suggest sending it in for service. Don't void your warranty.

 

[RenoTwolf]

Hi Trent,

I had the same problem but mine was more loss. I have a .30 and here is what fixed it. I had warranty work done at no charge. It has been working perfect.


Loss of power. Down in velocity...: Repair at no charge.
Power adjuster screw had loosened. Loctited and adjusted to factory specification. Shoots JSB 44's at 847 fsp at 1sd.


RenoTwolf

 

[tghaines]

I'll try my .30 cal barrel when I get back in a few days. That should isolate the o-ring I guess.
My local warranty repairer has a 3 week turn around due to their location.....but better have a working gun than not eh?

Thanks, Trent.

 

[GQ]

Watch this video from Ernest.

https://youtu.be/TedxFHkB4Sk

 

[GQ]

 

 

[Drumsnguns]

I have a brand spanking new Impact .25 and there is a huge amount of "slop" in my power wheel cam. I plan to take all of that out just like on Ernest's video. Right now, on max setting and factory default valve setting, EK Heavies are only going 817 fps.

Also my regulator gauge is set just a hair over 125 bar. Don't know if it's an inaccurate gauge or low setting.

I'll start with the power wheel then go from there.

 

[GQ]

Let us know after you fine tuned the power wheel.

 

[Utahairgun]

Agreed, the tuning wheel adjustment should help too, and you just as well locktite it when you do it because it will come loose again.

 

[GQ]

Exactly.

 

[tghaines]

I had my .30 cal pellets JSB 44.75gr doing 850fps. That about what Ernest started at. I'll check the power as is, then do the mod also.

Thanks guys

 

[Drumsnguns]

Re-tuning the Power Wheel did nothing...but after upping the regulator to the 140-145 range...that brought speeds up to around the 850 fps mark on MAX with 33.95gn JSB. The speeds are jumping around more than I'd like but I'm going to shoot a few hundred pellets through it this weekend and then re-chrony. I think that the regulator needs to break in and smooth out some. I believe the same thing happened with my .25 cal Cricket. Now it has an SD=2. Accuracy has jumped way up with this velocity.

 

[GQ]

I have used 2 different chrony and non of them having the same results. Sometimes 20 fps difference.
I dont trust those chrony very much.
We dont have other solutions, so what can we do to have a real accurate speed reading.
You can always buy an extreme expensive chrony but I would not.
For me , the most important is my Imact id accurate and consistant, and knowing my ballistic.

 

[tghaines]

You can use pellet drop or POI drop over distance to get the speed too. This assumes a set ballistic coefficient.
I'll try to find some info on this and post it, but iStrelok can do it for you.

I use the Chony as a start point and the iStrelok after that.

Note - I'm still trying to find time to fix my impact.

 

[jacobmo]

I have a loss of power on my impact also stripped it down and found the hammer seat came loose , screw it back in , some lock tight 6.47 and she works better then the day I got it 

 

[elh0102]

You can very easily determine if the breech seal is at fault. The rifle will sound different, and a piece of tissue draped over the breech when fired will let you know for sure. The change in sound is usually not subtle, I think you would have noticed.