FX M4 impact issues

[6gun]

I tried using the Huma barrel tensioner kit because it looked more appealing than the other kits at the time and it was cheaper. Also it definitely tensed up the barrel, there was always a massive POI shift to which ever side the rifle was laying on. It also made it louder than having the oem shroud on. Unless you're gonna run the 800mm barrel or the 30 at really high power, I wouldn't mess with one. Just get the carbon fiber sleeve insert and make sure your barrel liner is indexed correctly.

That's why I re machined the back cap on the carbon harmonic shroud to work with the carbon tensioner. It looked silly with just the thin barrel and a giant ronin on it, and it was also louder than I wanted. Mine would slightly hold a poi shift too before I changed 2 variables at the same time. Since I did 2 variables and I can't test them independently I can't tell you if the top strap change or stripping a screw with an electric screwdriver and bumping up the size of the cap screws in the front block helped fix the issue. Or if the combo did it.

I'm particularly physical with my 700mm impact because of a soft backpack case I prefer to use.

The more I talk impact with people the more I realize that it's really a nice piece of ballistics research components before it's just a pellet rifle, which won't be what most people are looking for.

 

[6gun]

The method of tensioning an Impact barrel makes no engineering sense at all.

When you perform a load analysis on the design you find the tension:

a. pulling the barrel through the clamp so over time with expansion and contraction due to temperature the barrel will slide forward and load the breech set screw.

b. places a torque on two long thin screws that attach the clamp to the trigger block so that any side load will twist that clamp and shift the POI.

Not just the 2 long screws from yaw, but it potentially pulls on the grub screw at the valve block too. It gets even more silly when you realize the liner is under compression in the barrel tube and you then put the barrel tube under tension.

Sure they could design the barrel adapter and block to have lugs like a rifle bolt to alow transfer port alignment and better retention and sell people another power block and independent barrel adapters. It has its flaws and they could totally redesign it, but it continues to be competitive and sell.

 

[JaceSpace1369]

That's why I re machined the back cap on the carbon harmonic shroud to work with the carbon tensioner. It looked silly with just the thin barrel and a giant ronin on it, and it was also louder than I wanted. Mine would slightly hold a poi shift too before I changed 2 variables at the same time. Since I did 2 variables and I can't test them independently I can't tell you if the top strap change or stripping a screw with an electric screwdriver and bumping up the size of the cap screws in the front block helped fix the issue. Or if the combo did it.

I'm particularly physical with my 700mm impact because of a soft backpack case I prefer to use.

The more I talk impact with people the more I realize that it's really a nice piece of ballistics research components before it's just a pellet rifle, which won't be what most people are looking for.

Yeah mine never originally suffered form poi shift, but I figured "it can't hurt to put it on" on top of that the longer pic rail with higher tolerance and 30moa would be added bonus. I ended up taking it off, not even a few weeks into it.And it just stayed in the closet for like a year before I threw it away.

I'm glad you managed to make yours workout for you though.

 

[6gun]

Yeah mine never originally suffered form poi shift, but I figured "it can't hurt to put it on" on top of that the longer pic rail with higher tolerance and 30moa would be added bonus. I ended up taking it off, not even a few weeks into it.And it just stayed in the closet for like a year before I threw it away.

I'm glad you managed to make yours workout for you though.

Our story is nearly identical. If the salesmen of youtube didn't push the heavy slug thing so hard, there would be lot more stock impacts and a lot less complaints.

 

[bzizzi]

I know FX guns very well, have been friends with Earnest Rowe for a long time, he taught me a lot about repairing and tuning FX airguns over the years, my first question is what caliber is your M4 ? Then we will move on to a known accurate pellet in that caliber, then set correct regulator pressure, then back out valve limit and bring up power with power wheel to+20-30 FPS above desired velocity that shoots best for the pellet you choose. Then place target at 50 yards and shoot some groups, lower the velocity by closing valve adjuster to the desired accurate velocity. Keep shooting groups and see what velocity is most accurate. Some pellets like the 25.4 gr JSB Exact in .25 cal don't really like going much over 900 fps. Other calibers like the .22 JSB Exact 25.4 gr like it up tp 970 FPS. Look at your regulator after sitting overnight, is it creeping up more than five bar then your regulator needs serviced, doesn't matter if gun is brand new, one of the O rings may have been damaged upon assembly. I see this happen all the time. If you don't own a chronograph then buy one, it is a essential tool in tuning the FX I pact or most other airguns, otherwise it's just a guessing game. The FX Impact is a incredible gun once set up and maintained correctly, I own three Impacts. Learning how to service and set up the Impact is mandatory, if you learn how the do this you will master it's capabilities and enjoy the gun much more seeing it's full potential.

 

[6gun]

I know FX guns very well, have been friends with Earnest Rowe for a long time, he taught me a lot about repairing and tuning FX airguns over the years, my first question is what caliber is your M4 ? Then we will move on to a known accurate pellet in that caliber, then set correct regulator pressure, then back out valve limit and bring up power with power wheel to+20-30 FPS above desired velocity that shoots best for the pellet you choose. Then place target at 50 yards and shoot some groups, lower the velocity by closing valve adjuster to the desired accurate velocity. Keep shooting groups and see what velocity is most accurate. Some pellets like the 25.4 gr JSB Exact in .25 cal don't really like going much over 900 fps. Other calibers like the .22 JSB Exact 25.4 gr like it up tp 970 FPS. Look at your regulator after sitting overnight, is it creeping up more than five bar then your regulator needs serviced, doesn't matter if gun is brand new, one of the O rings may have been damaged upon assembly. I see this happen all the time.

This is about as concise as it could be and should be pinned.

 

[UDABEGGER]

Has anyone had issues with there M4? I had to send my M4 back today with believed valve issues because fps is starting low and rasing up over about 40 shot string until leveling out! Utah airguns customer service is great and hassle free. But insight needed

The guys at UA will fix you for sure ! AMAZING RESULTS. The m4 is easy to master . Let warranty work for you !

 

[addison]

Can one of your guys measure the gap between the barrel shroud and the housing body of the gun. Im going to machine something to add tension to the barrel I just need that gap between everything. Why I have an open 3-axis I'm going to try to do something.

 

[addison]

Also the diameter of the barrel without the shroud

 

[Vetmx]

Another common issue with tensioning a FX barrel and even a real barrel is guys act like they are trying to stretch it. The old if a little is good then a lot is better way of thinking. Not the case. But all it takes is one guy claiming he tensions his barrel using a breaker bar and his gun is a “laser“ and now we have everyone going Dr. Crankenstein on the flimsy thing.

 

[6gun]

Can one of your guys measure the gap between the barrel shroud and the housing body of the gun. Im going to machine something to add tension to the barrel I just need that gap between everything. Why I have an open 3-axis I'm going to try to do something.

I recommend measuring what you have and adding the tolerance there. That way it's built to your gun and not a time waste if its off. It's install specific to a degree

 

[6gun]

Another common issue with tensioning a FX barrel and even a real barrel is guys act like they are trying to stretch it. The old if a little is good then a lot is better way of thinking. Not the case. But all it takes is one guy claiming he tensions his barrel using a breaker bar and his gun is a “laser“ and now we have everyone going Dr. Crankenstein on the flimsy thing.

Compressed liner, stretched barrel tube. It's a dance I don't suggest for those who aren't going to really spend the time on understanding their setup. Not everything is a Lego fit from gun to gun either.

Warning : im an enthusiastic 1-off custom part prototype sorta guy

I'm not throwing shade here but I don't think it's a wise endeavor if -
A) You don't have a whipping issue or a really obnoxious poi shift from looking at it, because there's a strong possibility you're about to gain one.
B) you send guns back for warranty instead problem solving and demanding parts.

I say this because the potential for things to go sideways is high. Just because I convey a concept that worked for me doesn't mean I remembered every hiccup and pain in the butt or tricky thing I did along the way. My gun was over 70 fpe in 22 and 700mm was doing the noodle wave.

If you do. I wish you the best of luck and best results.

BTW, I wrote all that crap and forgot you do tool and die. Youll probably be ok.

 

[Vetmx]

Compressed liner, stretched barrel tube. It's a dance I don't suggest for those who aren't going to really spend the time on understanding their setup. Not everything is a Lego fit from gun to gun either.

Warning : im an enthusiastic 1-off custom part prototype sorta guy

I'm not throwing shade here but I don't think it's a wise endeavor if -
A) You don't have a whipping issue or a really obnoxious poi shift from looking at it, because there's a strong possibility you're about to gain one.
B) you send guns back for warranty instead problem solving and demanding parts.

I say this because the potential for things to go sideways is high. Just because I convey a concept that worked for me doesn't mean I remembered every hiccup and pain in the butt or tricky thing I did along the way. My gun was over 70 fpe in 22 and 700mm was doing the noodle wave.

If you do. I wish you the best of luck and best results.

BTW, I wrote all that crap and forgot you do tool and die. Youll probably be ok.

Yep, preaching to the choir.

 

[addison]

Compressed liner, stretched barrel tube. It's a dance I don't suggest for those who aren't going to really spend the time on understanding their setup. Not everything is a Lego fit from gun to gun either.

Warning : im an enthusiastic 1-off custom part prototype sorta guy

I'm not throwing shade here but I don't think it's a wise endeavor if -
A) You don't have a whipping issue or a really obnoxious poi shift from looking at it, because there's a strong possibility you're about to gain one.
B) you send guns back for warranty instead problem solving and demanding parts.

I say this because the potential for things to go sideways is high. Just because I convey a concept that worked for me doesn't mean I remembered every hiccup and pain in the butt or tricky thing I did along the way. My gun was over 70 fpe in 22 and 700mm was doing the noodle wave.

If you do. I wish you the best of luck and best results.

BTW, I wrote all that crap and forgot you do tool and die. Youll probably be ok.

You got time to talk via call or text?

 

[herryer223]

Sounds like reg creep to me the pressure drops and the valve lets more air past and the velocity spikes amp regs suck lmao but if your psycho like me you can find a way the easy way put a second reg in huma regs are the same but deferent lol what I have found is a hybrid between a huma and my amp reg

 

[addison]

Sounds like reg creep to me the pressure drops and the valve lets more air past and the velocity spikes amp regs suck lmao but if your psycho like me you can find a way the easy way put a second reg in huma regs are the same but deferent lol what I have found is a hybrid between a huma and my amp reg

Currently Im fixing to hit up harbor freight in the morning and get t-handle hex wrench and other tools to tear into this raptor reg creep and when the fx m4 gets back im going to probably change out several items that @88tuebocoupe
Has suggested

​

 

[addison]

The start!

 

[6gun]

Yep, preaching to the choir.

This is a geek out of my logic for a couple iterations. If there's somewhere im wrong on, please set me straight.

Lesson learned if you bump the barrel hard enough that the metallic options would have enough friction to hold a shift that could be bopped out only sometimes. So i pondered the barrel going resonant and imagined it as a guitar string. It kind of only needs a palm mute to lessen the the amplitude of whatever waves im getting.

Delrin! That should slide back. It did, at the cost of damping the barrels resonance less effectively. It deformed to the point of little effect rather quickly. I wasn't buying any new material so i got the tensioner when it was particularly cheap somewhere.

I think with all the carbon barrel accessories and weight all I've really done is bumped up my barrels resonance a few harmonics with tension and then deadened it. Not to mention a previous mistake requiring an upgrade in shcs size for the bolts that hold the tensioner block.

So it may be that the setup that seems to be working for me at the moment may only work in these conditions.

 

[JaceSpace1369]

Our story is nearly identical. If the salesmen of youtube didn't push the heavy slug thing so hard, there would be lot more stock impacts and a lot less complaints.

I only ever got into the impact because I wanted to get into slugs. For the amount of money I dropped on just my Mk2 could've bought several mid priced guns or atleast a full retail impact

 

[6gun]

The start!

If your spinning the wheels, you're a wizard . Is that a cnc converted knee mill?