The purpose of this page is to document the factory changes / upgrades made on the FX Impact air rifle models, including Impact-X and Impact MK2, and to explain which modifications are required to upgrade an older model to the current spec.
If you are aware of any other changes please contact us so we can update this documentation.
The following parts have been upgraded / changed:
Reloading block – Earlier versions had non-serviceable hammer pin’s meaning if they were damaged the whole block needed to be replaced. MK2 versions are more serviceable and also have ‘MK2’ written on the side. Note, some very early MK1 guns had a 2mm cocking linkage pin, this was upgraded to 2.5mm on later versions, therefore if you have one of these early guns you will also need to replace this linkage (part 19021).
Old versions of the linkage and block are no longer supported as a spare part.
Valve tube / Plenum – MK1 impacts and Impact-X had 20mm external diameter plenums. Early MK1 models used an X-Ring inside this plenum with a nut holding it in place, but on later MK1’s and Impact-X this was replaced by an o-ring and a different nut.
The early valve tube and nut that used the x-ring is no longer available, but can be upgraded to the later MK1 valve tube. You will require the valve tube / plenum itself along with the screw.
The MK2 Impact uses a larger 23mm external diameter plenum. All MK1 rifles and Impact-X can be upgraded to this new plenum, but the valve house must also be changed to accommodate for this.
Valve House – MK1 Impact’s and the Impact-X have a smaller valve house to accommodate for the 20mm plenum. This is still available as a spare part and uses a separate valve seat that can be replaced.
The first batch of MK2’s used a larger valve house but used the same valve seat. This larger valve house with external seat is no longer supported as a spare.
Later MK2 Impact rifles use the larger valve housing but with an in-built valve seat. All previous versions of the impact can be updated to this new valve housing as long as the newer plenum / valve tube is also installed.
Pressure Gauges – All MK1 and Impact-X rifles used the smaller pressure gauge, which is still available as a spare (and also required on the dual bottle adaptor if changing an Impact to the bench version). MK2 rifles are fitted with a larger more accurate pressure gauge. All earlier impacts can be upgraded to this gauge.
Magazine System – MK1 Impacts and the Impact-X used the original Impact magazine (at the time termed ‘mega-mag’). For the MK2 this was upgraded to the ‘side-shot’ system which is easier to use and also higher capacity. Conversion kits are available to change any MK1 or Impact-X to the MK2 Sideshot system.
Pellet probe grub screw – Earlier versions of the Impact used a smaller grub screw and this was made bigger on later versions. Only pellet probes / feeding pins that take the larger grub screw are available as a spare, therefore if changing the pellet probe you may also need to purchase the grub screw.
Regulator Housing – The design of the regulator housing was changed during production of the MK1. The early design (serial numbers before 183534) had an 8mm outer diameter and the later version (serial numbers after 183534) 10mm outer diameter. The o-rings are also different on these two parts. Both are still available as a spare. Upgrading to the new style housing requires changing the whole main block and doesn’t make sense from an economics perspective.
Regulator Rod – Early MK1 Impacts used a 14mm (overall length) regulator rod and this was changed to a 16mm rod for all subsequent . Note this does not correspond with the change in regulator housing above. Both versions of the regulator rod are still available. If you have an early MK1 it is best to check the size in your rifle before ordering.
Valvestem – During production of the MK1 FX adjusted the design of the valve stem so that there was a guide on top of the threaded part. This is to help guide it into the hammer seat as installation was difficult and could easily lead to cross threading. The new version of the valvestem is compatible with all versions of the Impact. Installing the hammer seat to the valve stem is still tricky. The best method is to turn the valve-stem anticlockwise until you feel a ‘click’ then gently turn clockwise to start threading it on. If you feel any resistance stop, remove the valvestem and repeat.
Valvestem Spring – Early versions of the MK1 used 3 separate smaller springs. This was upgraded to one single spring for later MK1’s and all other versions. The new longer single spring is a simple and quick drop in upgrade to those early models.
Barrels – The Impact MK1 was supplied with the FX smoothtwist barrel. Impact-X and Impact MK2 were supplied with the newer smoothtwist-X barrel. There have been changes in barrel design within each of these two barrel types also. Changing from a smoothtwist barrel to the newer smoothtwist-X is possible.
Shrouds – The Impact MK1 and Impact-X were supplied with fixed shroud or telescopic shroud (dependent on country of purchase). Common spares are still available for the telescopic shroud system but the complete shroud is not. The MK2 rifles all use a fixed shroud.