Fx Impact Mods for more FPS / FPE

Forums PCP Airguns Fx Impact Mods for more FPS / FPE

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    edosan
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    DISCLAIMER:

    In this post you will find some mods, in order to get more power out of your FX impact. Some mods can be potentially VERY dangerous!

    Any change you make to your airgun will probably void your warranty (if any) even if someone is telling you that you will not. And is 100% your responsibility. If you are not comfortable doing changes to your airgun and still want to make them PLEASE go to an AirGunsmith. 

    Before making any mod, be sure you can go back, meaning get the part to replace in case of problems.

    Before making any mods make sure is legal in your country. You will be the one with problems if not.

    Read the tread before make questions regarding any mods.  (do not be lazy! ;) )

    If you change your Impact (or any other airgun) using anything you read here you agree that any problem will be on you, and AGN, FX , me (Edosan) or any other vendor or member here have CERO liability on it.  

    MODS you can find:

    – Transfer Port elongation in brass and Pellet Probe: it will speed up your pellets, specially on 0.22 cal. Making this you eliminate restrictors of air.

    – Valve Seat Change: Remove restriction of air in the valve, making the valve seat larger. Stock Valve Seat is 5.5mm and in latest Mk2 is 6.35mm

    – Removing C3 bumper and replace that with a Delrin: the hammer will strike the hammer seat with less cushion, that will make the valve stays open a bit more, and the delring is stronger than the PU90 o'ring (it will receive more punishment without complains ;) )

    – 1 mm, 1.5mm, 2mm spacer at the end of the spring: that will add the max tension to the spring

    – Hammer Weight: Same as the spacer (head) plus add more weight to the hammer, in order to fully open the valve at hi reg pressures.

    – 600 mm to 700 mm barrel extender (so you can use a 700 liner in a 600mm barrel)

    – Larger External Plenum

    – Valve Housing modification

    – Block mod for external plenum with larger thread dimensions

    —————————–

    Hi Guys! I have been on the search looking for your mods and I found a few threads about it, including plenums, hammer weight, Enlarging TP, spring spacer, belleville washers, humma high pressure reg, among others.

    If is not too much to ask, can you share your mods on the Impact (or Crowns) with pictures (if possible) ? Thanks in avance!

    Maybe I can make a compilation of mods here if there is enough quorum to do it

    PS: Other mods (non FPE related) are welcome too!

    Edit: several mods on this thread, read it if you are interested

    • This topic was modified 1 month ago by edosan.
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    Saltlake58
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    No mods on my end, but just completed a full Impact rebuild and will be tuning as soon as the weather cooperates a bit.  Just too cold this week.  Will tune for JSB 33.95's (.25 cal) for about 830-ish fps.  Less energy, better accuracy at long range.

    Past that, thinking about a better moderator.  

    So many toys, so little money.

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    edosan
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    Saltlake58

    No mods on my end, but just completed a full Impact rebuild and will be tuning as soon as the weather cooperates a bit.  Just too cold this week.  Will tune for JSB 33.95's (.25 cal) for about 830-ish fps.  Less energy, better accuracy at long range.

    Past that, thinking about a better moderator.  

    So many toys, so little money.

    That tune sound about right, I get that on that config (very accurate). Thinking about slugs those need 950fps +-   

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    ackuric
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    Very little information about the FX impact factory specs, for say port size, plenum volume, valve throat OD / poppet OD…would be nice to know

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    edosan
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    It will for sure

    I am impatient, I know FX will release a Power Kit soon (no mystery there, several post about it) just curious about you Impact Geeks! ;) 

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    AirSupply
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    With just 2 modifications to my Impact the speed of the .25cal King Heavies went from 860fps to just over 900fps. This is with a 600mm barrel. 

    1 Ernest’s larger valve seat. 

    2 Elongated the TP on the barrel and the probe. 

    Without having to change the TP on my 700mm .30cal barrel Ernest’s Valve seat also bumped up the the speed of the 44g jsbs above stock to over 900fps. 

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    edosan
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    How did you make the TP elongated? Dremel or mill? 

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    AirSupply
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    Dremel. Had the barrel in a small vice. Slipped a piece of thin rubber into the barrel in line with transfer port to protect the opposite side of the breach from the tip of the dremel. Used magnifying glasses and a head torch. Worked very slowly and carefully. 

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    AirSupply
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    The barrel is a Lothar Walther polygon barrel .25cal. It has been machined down to fit the Impact. 

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    Hatmike
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    I have a 30 cal barrel that was Fredrick axelsons and alex of fx barrel was used in last ebr and rocky mountain by Fredrick.they drilled all the wat through the barrel and prob.all the way both sides.barrel added 60fps.it in family forever.

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    edosan
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    AirSupply

    The barrel is a Lothar Walther polygon barrel .25cal. It has been machined down to fit the Impact. 

    Nice..I am doing that (Dremel) this weekend probably.

    Nice job! and how that barrel compared with the ST or STX? Slugs?

     

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    edosan
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    Hatmike

    I have a 30 cal barrel that was Fredrick axelsons and alex of fx barrel was used in last ebr and rocky mountain by Fredrick.they drilled all the wat through the barrel and prob.all the way both sides.barrel added 60fps.it in family forever.

    That confirm my thoughts, just enlarging the TPs a bit it will increase the fps…plus a hammer weight (easy to do) should add a few more FPS

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    mtnGhost
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    edosan

    Hatmike

    I have a 30 cal barrel that was Fredrick axelsons and alex of fx barrel was used in last ebr and rocky mountain by Fredrick.they drilled all the wat through the barrel and prob.all the way both sides.barrel added 60fps.it in family forever.

    That confirm my thoughts, just enlarging the TPs a bit it will increase the fps…plus a hammer weight (easy to do) should add a few more FPS

    What are the details for adding a hammer weight? I had it in my mind that a new one using heavier steel would have to be machined.

    This is a GREAT thread idea BTW! 

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    edosan
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    mtnGhost

    edosan

    Hatmike

    I have a 30 cal barrel that was Fredrick axelsons and alex of fx barrel was used in last ebr and rocky mountain by Fredrick.they drilled all the wat through the barrel and prob.all the way both sides.barrel added 60fps.it in family forever.

    That confirm my thoughts, just enlarging the TPs a bit it will increase the fps…plus a hammer weight (easy to do) should add a few more FPS

    What are the details for adding a hammer weight? I had it in my mind that a new one using heavier steel would have to be machined.

    This is a GREAT thread idea BTW! 

    Nothing specific, just some earlier Fx power kits talking about it … but is quite simple…hope someone with experience on it can add something 

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    RDHang
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    AirSupply

    With just 2 modifications to my Impact the speed of the .25cal King Heavies went from 860fps to just over 900fps. This is with a 600mm barrel. 

    1 Ernest’s larger valve seat. 

    2 Elongated the TP on the barrel and the probe. 

    Without having to change the TP on my 700mm .30cal barrel Ernest’s Valve seat also bumped up the the speed of the 44g jsbs above stock to over 900fps. 

    The valve seat you got, was it the 5.85mm valve seat or the 6.5mm?

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    edosan
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    AirSupply

    The barrel is a Lothar Walther polygon barrel .25cal. It has been machined down to fit the Impact. 

    Air, how is the barrel working? what at you shooting?

     

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    edosan
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    AirSupply
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    edosan

    AirSupply

    The barrel is a Lothar Walther polygon barrel .25cal. It has been machined down to fit the Impact. 

    Air, how is the barrel working? what at you shooting?

     

    Great barrel and shoots the King Heavies very well. I haven’t really done a lot of work with slugs. It does shoot the H&N grizzlys quite well. 

    I have a second hammer that is 3grams heavier than stock. It will bump up power again when combined with the other 2 modifications. 

    When I get my .22 slug liner I’m hoping to get the performance I’ll need from just Ernest’s valve , elongating the TP and regulator pressure. I don’t particularly like using the heavier hammer because when you start increasing power that way it changes the nature of the gun. More noise and more recoil. It’s honestly not as enjoyable to shoot. Even the larger valve seat has a slight affect on that. 

    My advice is start slowly with any modifications. Tp first and see where your at before taking another step. If you go all out you may end up with a gun that is not so nice to shoot!

    Michael

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    mtnGhost
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    AirSupply

    If you go all out you may end up with a gun that is not so nice to shoot!

    Michael

    I'm already noticing the recoil differences with variations of HST knob settings alone. Not that I'm bothered by those, but the natural concern I have then becomes the question of the associated (stock) internals being able to stand up to the abuse.

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    edosan
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    The c3 bumper usually get busted after a while, need to be replace

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