FX Flimsy fx impact barrel

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Lahtide

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Aug 21, 2025
10
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I finally have a barrel i feel will be stiff enough to insure no poi change. I will now start testing group size.

FIRST I used a carbon fiber barrel liner which I epoxy afixxed. Secondly I measured and purchased a barrel shroud carbon fiber liner (14mm/16mm) which i also epoxy glued in place. With that I have a barrel block with clamp screws i counter bored to hold the rear end of CF barrel shroud liner.
These mods did wonder for stiffing yet still wasn't there. Lastly I used some 15mm package foam to build a "stiffener". It slid between the tank and barrel as well as barrel and scope rails with a bit of tension. Next i cut pieces to place on either side. Then I zip tied the whole apparatus together. If after testing it turns out positively I will make a more permanent piece with aluminum sides and screws. I will still use foam between the barrel and bottle and scoperail then foam line the aluminum side pieces. Well off to test.
 
Photos of barrel stiffener

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To clarify, I'm by no means a bench rest shooter. I am an avid hunter who big game hunts (deer, hogs) pest hunts and small game.
I'm setting this Impact M3 500mm barrel up for Cyote, pigs, squirrels. I hunts deer and hog with a Airforce Texan in 9mm with a 170gr hollowpoint.

I said that to post the 5 shot groups I just shot after adding my homemade "barrel stiffener "i
I'm happy to see it didn't negatively impact my groups. While my groups aren't spectacular they are on par with my ability.
Shooting from a rest with no bags, just wood to gun.
50 yard 5 shot groups with slugs :
NSA 26.8GR: 1.42 inch remove flyer .5670
H&N GRIZZLY: .9040 4 SHOT 1.10 5 SHOT
EUNJIN 43.2GR PELLETS .5935 4 SHOT .7890IN 5 SHOT.

I am still testing, looking for a slug that will shoot better than these. So far I have tested a few others with about the same results.
My FX v2 chronograph is on the blink so I'm flying blind for velocity at the moment. The slugs are flying in the 900/950 range and the pellet is too fast at around 1045. These are numbers from before my chronograph messed the bed. I can tune somewhat by sound. At least to the point of air management. I can tell when air is leaving the barrel excessively. When I replace my chronograph I will more accurately test.
 
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Be sure not to over or under torque the barrel nut, or at least tighten in consistently. What I do is hand tighten the nut till it contacts the liner, then tighten 1/4 turn. No more. You and also try indexing the barrel by shooting 5 shot groups after turning the liner 45 degrees at a time. Then pick the group that is directly above the point of aim and keep the liner there. I also use a Dremel to grind a tiny dot on the end of the barrel (not the crown please) so I know where to place it each time.
 
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Lahtide said:
View attachment 588811To clarify, I'm by no means a bench rest shooter. I am an avid hunter who big game hunts (deer, hogs) pest hunts and small game.
I'm setting this Impact M3 500mm barrel up for Cyote, pigs, squirrels. I hunts deer and hog with a Airforce Texan in 9mm with a 170gr hollowpoint.

I said that to post the 5 shot groups I just shot after adding my homemade "barrel stiffener "i
I'm happy to see it didn't negatively impact my groups. While my groups aren't spectacular they are on par with my ability.
Shooting from a rest with no bags, just wood to gun.
50 yard 5 shot groups with slugs :
NSA 26.8GR: 1.42 inch remove flyer .5670
H&N GRIZZLY: .9040 4 SHOT 1.10 5 SHOT
EUNJIN 43.2GR PELLETS .5935 4 SHOT .7890IN 5 SHOT.

I am still testing, looking for a slug that will shoot better than these. So far I have tested a few others with about the same results.
My FX v2 chronograph is on the blink so I'm flying blind for velocity at the moment. The slugs are flying in the 900/950 range and the pellet is too fast at around 1045. These are numbers from before my chronograph messed the bed. I can tune somewhat by sound. At least to the point of air management. I can tell when air is leaving the barrel excessively. When I replace my chronograph I will more accurately test.
Click to expand...
I may be able to purchase a different gun, however at what expense?
I am very particular on the torque on barrel. The issue was with flex. I could flex the barrel a good bit with a finger and thumb.

My proof of concept, crude, was somewhat effective.
I fashioned version two (photo below) with a couple of pieces of aluminum a bit of leather and two 4 mm screws and nuts. It's much better and the results were as well.
I shot two 5 shot groups with the H&N slugs at the same 50yrd zero. Results were .37in and .81in with a flyer .53 without flyer
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Vetmx said:
Did you ever just consider a better hunting gun. There are quite a few guns out there that the barrel and POI issues are not even something you think about. An Impact can be a good hunting gun but it really shines as a toy for guys who‘s hobby is always looking for greener grass.
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Would you purchase me one? Another gun would come st an expense. I just made the one I already have better with scraps I had in a bin.
 
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6gun said:
I think you may be fixated on the barrel when it could be (and likely is) the state of tune. I've been thru it with my 700mm. Harmonic tuners can help bring it down, but aren't as noticed on 500mm ime.
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I'm aware of tuning and it's effect. As I was explaining in the thread I was concerned with the amount of flex no amount of tuning will create a stiffer barrel. I could move the barrel a good bit with a finger and thumb. I cured that issue and seem to have helped harmonics to boot. I would hate to see the amount of flex in a 700mm barrel. You could probably tie it in a knot.
 
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Vetmx said:
Did you ever just consider a better hunting gun. There are quite a few guns out there that the barrel and POI issues are not even something you think about. An Impact can be a good hunting gun but it really shines as a toy for guys who‘s hobby is always looking for greener grass.
Click to expand...
At a Knob Creek Automatic Weapons Shoot, I saw a demonstration using a Wilson Combat AR - 15.

The rifle was beat to crap, scope was a prismatic type and missing a lot of paint, even the Troy 45° Offset Combat sights were heavly marred.

The owner locked a full magazine into the lower, grabbed the muzzle end of the hand guard and threw it down range end over end onto gravel and rocks.

He went down range picked it up, came back to the firing line, racked a round, and then using the prismatic, placed three rounds centered into the torso A Block of a USPSA/IPSA target at 100 yards, he then rocked the rifle over and placed 3 rounds into the torso A Block of a USPSA/IPSA target at 50 yards using the Troy Offset Combat sights.


The Airgun Industry does not make a single rifle that durable. Every air rifle on the market would be permanently broken and totally dysfunctional following such a test.
 
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Motorhead said:
Do be aware ... while full length CF will stiffen the barrel outside the receiver connection, the place where CF stops and CF is butted to receiver will still flex at that specific spot. FYI
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That's why I counter drilled the barrel block so the cf would slide in. I drilled 1/2 way so I can put retention on the shroud and tension on the CF shroud cover. I saw the flex you mentioned and made a new one......thankfully I bought a 4 pack. It took three tries to get what I wanted.

Even with a barrel sleeve and a shroud sleeve I was getting more flex than I felt comfortable with as this is going to be in the field not just a bench. I think I have it were I want it now. I put the gun in my chest freezer and want to see where it will shoot at 32 degrees instead of the 90 degrees it is now. I may have to figure something out for weather????
 
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Lahtide said:
That's why I counter drilled the barrel block so the cf would slide in. I drilled 1/2 way so I can put retention on the shroud and tension on the CF shroud cover. I saw the flex you mentioned and made a new one......thankfully I bought a 4 pack. It took three tries to get what I wanted.

Even with a barrel sleeve and a shroud sleeve I was getting more flex than I felt comfortable with as this is going to be in the field not just a bench. I think I have it were I want it now. I put the gun in my chest freezer and want to see where it will shoot at 32 degrees instead of the 90 degrees it is now. I may have to figure something out for weather????
Click to expand...
Thank you for your input by the way. You were the only one who read the post and answered accordingly......my complaint wasn't tune related it was barrel flex, can't tune that out.
 
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Lahtide said:
It's the flex I was concerned with. I can tune to most any projectile but you can't tune out flimsy.
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That's my point 500 isn't really a flex issue unless you want it to feel like it's a tc encore bull barrel. The groups your posted look like an incomplete tune rather than barrel flex(not trying to be insulting) Yes we can all tune a projectile to shoot ok, but tuning the gun to harmony and minimal muzzle blast is the key. A bone stock 500mm setup with a plastic tensioning collar will 1 hole for you at 50 fpe in 22(my hunting partners gun) . I've done that and 1 hole with 700(my gun) before the carbon tensioner.

Our unfounded need(I'm with you here) to bounce our guns around and have powder burner rigid barrels gets us to carbon tensioner and then tuning becomes a new game and the old principles become less applicable and the hammer sequence comes to play for group sizing ime.

Combine that with a ballistics solving optic and it took me a year to tune out the things I didn't want, and I'm still not done. I had the carbon harmonic shroud re machined to fit over the tensioner with the carbon liner tube in there trying to get it to do what I wanted. And even mounted the tensioner barrel block with larger dia cap screws and re machined my trigger block.

The preload on your liner is stretched back off when the barrel tube is pulled by the tensioner too. I didn't think that mattered, it does. That's why my impact is a Bench gun now and a 25 cal dreamline compact is my walk around gun.

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My comment is I think you're looking the wrong way. Take the fx system out and put a lw in it and save some time. It will skip all the jb weld and guess work.
Lahtide said:
Thank you for your input by the way. You were the only one who read the post and answered accordingly......my complaint wasn't tune related it was barrel flex, can't tune that out.
Click to expand...
 
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Lahtide said:
That's why I counter drilled the barrel block so the cf would slide in. I drilled 1/2 way so I can put retention on the shroud and tension on the CF shroud cover. I saw the flex you mentioned and made a new one......thankfully I bought a 4 pack. It took three tries to get what I wanted.

Even with a barrel sleeve and a shroud sleeve I was getting more flex than I felt comfortable with as this is going to be in the field not just a bench. I think I have it were I want it now. I put the gun in my chest freezer and want to see where it will shoot at 32 degrees instead of the 90 degrees it is now. I may have to figure something out for weather????
Click to expand...
Use of CF compounds another issue when paired to an aluminum or alloy receiver and then a steel barrel ...

The thermal dynamics in expansion/contraction are all different from one another and to mate any of them presents needing a fit to allow this motion, as bonding them "Either Or" may very well create tension/stress that will move your POI with enough temperature change ?

Just sharing ... no critique intended ;)
 
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