FX FX Impact M4 - 700mm & 800mm question

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adzmullen

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Apr 12, 2022
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Lancashire, United Kingdom
Hi,

Does anyone know if the new FX Impact M4 700mm or 800mm versions come with a built in barrel tension clamp / block as standard from the factory ?

I read somewhere they did, although I can find no reference to this, but I notice the FX website does not list this as an upgrade / accessory on their website, this would make sense if it has one built in already, but not if it isn't.

Could an owner of one of these models clarify this for me ?

Thanks in advance
 
I can confirm that the M4 does not have a built in barrel tension clamp. Also, the clamp block has been very slightly redesigned together with the new top rail. As a result of this, you cannot use the barrel clamp block from the M3 (maybe with a dremel, but I did not go down this route).

Also noteworthy, the M3 barrel clamp block does have a small circular edge in which the tensioned carbon barrel slots. The M4 regular barrel block
does not have this. So you currently cannot use the tensioned shroud on the M4. Unless there's a add-on replacement part of which I'm unaware. On the other hand: it shoots well enough with the standard untensioned shroud :)
 
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airman_o said:
I can confirm that the M4 does not have a built in barrel tension clamp. Also, the clamp block has been very slightly redesigned together with the new top rail. As a result of this, you cannot use the barrel clamp block from the M3 (maybe with a dremel, but I did not go down this route).

Also noteworthy, the M3 barrel clamp block does have a small circular edge in which the tensioned carbon barrel slots. The M4 regular barrel block
does not have this. So you currently cannot use the tensioned shroud on the M4. Unless there's a add-on replacement part of which I'm unaware. On the other hand: it shoots well enough with the standard untensioned shroud :)
Click to expand...

Super, thanks for the clarification :)

Glad its working well without it too.

Much appreciated sir
 
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Maybe this will make you feel better. I have two m3’s one setup with the carbon barrel tension system and the other with the factory standard shroud. The standard shroud is very accurate and easily matches the tensioned rifle if not better. I wouldnt spend the money on the tension system again after this experience.
 
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Can any body tell me anything about the 800mm barrel assembly, disassembly. I took mine apart, put it back together after some upgrades and it shot great. However the other day I reached up to take off the stock moderator and try out my new donnyfl, and instead of the moderator turning, the shroud turned, just a little. And I decided I should screw it right before continuing. Well after that, my poi has greatly shifted and my accuracy is not good. Has anyone experienced such a thing?
 
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LDP said:
Maybe this will make you feel better. I have two m3’s one setup with the carbon barrel tension system and the other with the factory standard shroud. The standard shroud is very accurate and easily matches the tensioned rifle if not better. I wouldnt spend the money on the tension system again after this experience.
Click to expand...
What barrel lengths ?
 
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bjeffroson said:
hi I have a question I'm new to the slug world and I have just ordered a fx m4 25 cal with the 800mm barrel and i plan to shoot a 40gr ish slug so will i need a slug power kit for it?
Click to expand...
Hi,

For the best results yes you will, the slug power kit comes with a pin probe to seat the slug better & more importantly it comes with a lighter spring and heavier hammer so it can hit the value harder & keep it open a little longer allowing more air through, which in turn provides more power needed for heavier slugs.

It is also recommend to get the heavy slug liner and I personally use that in conjunction with the carbon sleeve to stiffen the barrel up as much as possible.

I bought a C1 removal tool which made fitting the heaver hammer & replacement spring easier, I would recommend picking one of these up, but it is not always required. One word of advice don't install the rubber ball in an impact M3 / M4 that comes with the kit, it is not required and it will massively reduce your power if installed.
 
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adzmullen said:
Hi,

For the best results yes you will, the slug power kit comes with a pin probe to seat the slug better & more importantly it comes with a lighter spring and heavier hammer so it can hit the value harder & keep it open a little longer allowing more air through, which in turn provides more power needed for heavier slugs.

It is also recommend to get the heavy slug liner and I personally use that in conjunction with the carbon sleeve to stiffen the barrel up as much as possible.

I bought a C1 removal tool which made fitting the heaver hammer & replacement spring easier, I would recommend picking one of these up, but it is not always required. One word of advice don't install the rubber ball in an impact M3 / M4 that comes with the kit, it is not required and it will massively reduce your power if installed.
Click to expand...
Does the rubber ball really reduce power? I have it installed in my setup and I just never took it out. Like any idea how many fps difference?
 
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dnye1986 said:
Does the rubber ball really reduce power? I have it installed in my setup and I just never took it out. Like any idea how many fps difference?
Click to expand...
Hi, yes it it makes a big difference, my .22 cal Impact M4 is tuned at 990-1000fps shooting a 34gr slugs, I could get it to go higher but the rifle isn't far off being maxed out as it is, if I make no changes at all and just install the ball it reduces to about 780fps, its a big difference and big reduction in power.

If it is installed it shortens the stroke of the valve rod so it cannot hit the valve as hard, this means less air is released meaning less power.

The ball is only for earlier versions of the Impact, From the M3 upwards its not required, it will actually reduce power. Test it for yourself, it only takes 10 seconds to remove the ball and no tools are required.

Hopefully this helps :)

1733399687027.png
 
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