FX FX Impact M3 Compact Tuning Pellets

[SprayNPray]

Hello all first post random question…

I have an Impact M3 compact and I shoot pellets only in .177 and .30 in 500mm with superior stx barrels.

I have first regulator at 155 factory and my second at 110 which I have heard is basically as high as you want to go with the stock hammer. This is my starting point for .30.

Here is the question. I shoot a lot from in my house out to about 25 yards in .177 in my backyard from my kitchen table and have been keeping my second regulator set at 110. I then close the valve to somewhat above the velocity I want for the pellet I’m shooting and then lower hammer tension to dial in the speed. I understand this is prob very lazy however I can literally pound a nail in a board from 25 yards. I am wondering what the disadvantage is to tuning the gun this way?

 

[nervoustrig]

From this description, there's really no way to know how the hammer spring tension is set in relation to the regulated pressure. The hammer strike might be pretty close to optimal or substantially too strong (presumably not set too light based on the favorable accuracy).

If the former, all is well.

If the latter, it could be stressful to the C3 bumper and the valve stem.

 

[SprayNPray]

From this description, there's really no way to know how the hammer spring tension is set in relation to the regulated pressure. The hammer strike might be pretty close to optimal or substantially too strong (presumably not set too light based on the favorable accuracy).

If the former, all is well.

If the latter, it could be stressful to the C3 bumper and the valve stem.

Thank you for the info. My micro is around 2.5 macro 8 which changes a little based on the pellet. Can the hammer strike still be dangerous at these lower levels? I do get velocity changes in each directions with the macro wheel. My extreme spread is around 7fps which is higher than when I set the second reg more optimally for .177, but for the short distances I typically shoot .177 it doesn’t seem to matter for accuracy. I guess my main goal is to not degass all the time since I like going back and forth with calibers right now.

 

[nervoustrig]

Can the hammer strike still be dangerous at these lower levels?

With so many potential variables--different springs, different weight hammers, production tolerances, etc.--I wouldn't want to wager a guess.

And then I'm going to turn right around and say based on this statement...

My avg spread is around 7fps

...that it probably isn't pounding the daylights out of the bumper. If if were, the expectation would be that the dwell would shrink so short that the ES would get all out of whack.

To get a better sense, all you'd need to do is open up the valve limiter completely and see how much the velocity climbs. If it's a substantial amount, say 100fps or more, it suggests the valve was being driven pretty forcefully into the bumper.

 

[SprayNPray]

Sorry that was me using the wrong terms. It should be extreme spread. I edited my comment. Sounds like I should just degass though to be safe and tune more efficiently.

On that same note though I have a fear that I might get oring leaks from degassing a lot. Is that a typical problem?

Thanks again for the help.

 

[SprayNPray]

To get a better sense, all you'd need to do is open up the valve limiter completely and see how much the velocity climbs. If it's a substantial amount, say 100fps or more, it suggests the valve was being driven pretty forcefully into the bumper.

Yes that answers the question. If I open the value up I can get well over 1000fps and typically shoot around 800 to 900fps pending the pellet. I think you just saved me from some long term issues!

 

[Trucker3573]

If your gun is internally stock you are def not hitting the valve to hard with 110 bar reg and your micro at 2.5. I know all guns are different but from my experience that is actually quite low.

 

[nervoustrig]

On that same note though I have a fear that I might get oring leaks from degassing a lot. Is that a typical problem?

Over the years, I’ve neither found nor read any meaningful evidence of O-ring problems arising from degassing and refilling. At least not in the usual circumstances where the user does it occasionally. However I have become aware of a particular sort of heat stress and degradation affecting the seals at the high pressure end of a regulator. Speaking of the O-ring on the small end of a regulator piston and the one on the adjuster (when applicable). This heating occurs each time the regulator cycles, on account of the pressure drop of firing (cooling) followed by the pressure rise of the refill (heating) of the plenum. It slowly and gradually cooks the O-rings, so to speak, and they eventually become hard, brittle, and incapable of sealing properly.

So how does this normal, unavoidable heating effect from ordinary use relate to the occasional degas and refill? As in, does one have a disproportionately greater effect than the other? Well, I guess it just depends. For example, although a complete refill from zero clearly produces a greater temperature rise, this situation is not happening all that often. Whereas the heating from normal use is happening probably hundreds or thousands of times for every 1 time you do a complete degas/refill so my intuition is not to fret over it. Besides, it’s unavoidable that someday the regulator will need to be serviced. Other O-rings too. I mean of course you don’t want to needlessly hasten it but worst case it’s just an inconvenience when the day comes.

 

[SprayNPray]

Over the years, I’ve neither found nor read any meaningful evidence of O-ring problems arising from degassing and refilling. At least not in the usual circumstances where the user does it occasionally. However I have become aware of a particular sort of heat stress and degradation affecting the seals at the high pressure end of a regulator. Speaking of the O-ring on the small end of a regulator piston and the one on the adjuster (when applicable). This heating occurs each time the regulator cycles, on account of the pressure drop of firing (cooling) followed by the pressure rise of the refill (heating) of the plenum. It slowly and gradually cooks the O-rings, so to speak, and they eventually become hard, brittle, and incapable of sealing properly.

So how does this normal, unavoidable heating effect from ordinary use relate to the occasional degas and refill? As in, does one have a disproportionately greater effect than the other? Well, I guess it just depends. For example, although a complete refill from zero clearly produces a greater temperature rise, this situation is not happening all that often. Whereas the heating from normal use is happening probably hundreds or thousands of times for every 1 time you do a complete degas/refill so my intuition is not to fret over it. Besides, it’s unavoidable that someday the regulator will need to be serviced. Other O-rings too. I mean of course you don’t want to needlessly hasten it but worst case it’s just an inconvenience when the day comes.

This makes me feel better. I’ve retuned to 4 valve lines reg 2 70 micro 1.5 for jsb .177 monsters. No speed changes anymore when I increase the macro wheel so it looks like a decent tune with es 2. 803 to 805 fps. Edit it is also impressively quiet again with the sarissa can I have on it.

I suppose I’m going to have to decide on a pellet in each caliber and get a second gun so I have something to play with when I’m eventually fixing this one!