So I purchased a FX Impact MKII in .25cal. I love the gun and it shoots well and ive made a lot of kills out to 200 yards. So this is what ive done. I installed a 700mm Superior heavy liner (carbon fiber rapped) also installed Ernest Rowes duel transfer port from 910 air guns (it sits to deep and mag does not go in unless you pull the barrel out some) and i feel like thats not right and the transfer port holes are not lining up right. I installed the fx slug power kit (spring, spacers and ball) and polished everything with 6000 grit (super shinny and smooth). I did not use the slug probe in the kit due to i have already installed the Utah air guns Nielson .25cal slug probe and block (the $79 they sell). I am at 150bar on the power plenum reg and the hammer spring is tightened down to where if i tighten it anymore the gun will not cock. I am shooting NSA 36.2 flat base slugs and all I can get out of the gun is 958fps on max wheel location. Ive messed with pressure ive messed with hammer spring and this is all she has from what i can see. I wanted to be at 1050ish fps for a flatter trajectory at long range. Also i was wanting to get a .35 call barrel and set up but if i cant push a .25cal slug to 1050fps how am i going to have enough power to push a .35cal slug? Am I missing something? Sorry for the long past guys
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Tuning FX Impact MKII .25 lots of mods but not lots of speed
- Thread starter RyanTugSmith
- Start date
I did a few mods to my Gen1.5 Impact-X and last time I had the .25 700 slug A barrel on it I was getting the 36.2 NSA slugs up to near 1020fps with the reg at 135-140bar.
Port matching is very important if you want max power at a given pressure it needs to be near perfect. I tried the FX pin probe and dropped a few fps from my modified stock probe and jammed slugs into my barrel port, so I took it off. Don't know for sure that I could get to 1050fps but my hammer spring was not maxed and I can turn the reg pressure up a bit as well. So there is a good possibility it could happen anyway. I was shooting the slugs at around 980fps but dropped the velocity down to 960fps for a bit more accuracy and better shot count. Hope this helps you out in some way. I shot allot of spray paint cans at 200 meters. Fun it is!
https://www.airgunnation.com/topic/my-trip-down-the-rabbit-hole-with-gen1-impact-modding/?referrer=1
Port matching is very important if you want max power at a given pressure it needs to be near perfect. I tried the FX pin probe and dropped a few fps from my modified stock probe and jammed slugs into my barrel port, so I took it off. Don't know for sure that I could get to 1050fps but my hammer spring was not maxed and I can turn the reg pressure up a bit as well. So there is a good possibility it could happen anyway. I was shooting the slugs at around 980fps but dropped the velocity down to 960fps for a bit more accuracy and better shot count. Hope this helps you out in some way. I shot allot of spray paint cans at 200 meters. Fun it is!
https://www.airgunnation.com/topic/my-trip-down-the-rabbit-hole-with-gen1-impact-modding/?referrer=1
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where is the valve spring under the barrel set?? If you have it cranked all the way tight that will explain y you cant get the speed. set it at the 4th line. I was slinging 38 gr at 930 fps with 126 Bar regulator setting on my 700 mm MK2 impact.
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It sounds like you have pushed out the barrel alignment pin on the block causing alignment and mag loading issues. I would straighten/fix the pin, the ports need to be aligned. I would also push some slugs through the bore and see if you can take a little more off the slugs for less drag and increased velocity, also adding pure silicon grease to slugs. I would turn the valve knob all the way out past 4 until it hits the stop just as a test to see if you increase in velocity any. I would also replace both O-rings on each side of the port.
Here is how I did my probe. I just took out the top bar so the air would not catch on it. I smoothed out the edges on the Huma. Not pretty but the main thing is smooth flow.
Here is how I did my probe. I just took out the top bar so the air would not catch on it. I smoothed out the edges on the Huma. Not pretty but the main thing is smooth flow.
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Yes the adjustment on the nob under the barrel is at 4 out. Sorry i didnt add that into my first post. The O rings are brand new on the dual transfer port. I do feel like the Ernest Rowe dual transfer port from 910 air guns is a big part of my problem with that alignment notch being a little to deep. I feel like the ports arent all lining up. Im fixing to break it all down and see what i find. Triggertreat does your modified pellet probe work better than a slug pin probe?
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I couldn't say...I have not tried the pin probe. I did gain ~ 40 FPS with the dual Huma and probe mod together. You should be able to get those NSAs to at least 980. The NSA 33.5gr over 1000 with the standard Superior liner.
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Well i went in the dual transfer port and rounded out the edges and polished up a little. Also ground down the NSA pine probe some and polished it. I put it all back together and im at 990fps to 994fps. Im good with that on the 36.2 NSA. I still feel like you should be able to sling them at 1050fps but hey it is what it is i guess. So just that little mod made 32fps faster. Crazy how so little made such a big difference.
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Sounds like you are on the right path. I notice with some slugs I can get blow by with speeds not as high as others. I can launch the 45gr pellets at 1024. Just depends on shape sometimes.
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I would like to add here a small comment.
The hammer spring or the valve spring specs from a kit you buy...not neceserely will give you a best performance/numbers you expecting from your purchase.
Me in example I did not buy those kits, when I wanted to buy all were out of stock, so I ended up browsing inventories in automotive supply stores. And these springs I am using right now @970 fps/140 bar/33.9 grain in .25 cal. And I can go higher speed but no need for it.
Improvise, try things...don't just buy from shelfs
The hammer spring or the valve spring specs from a kit you buy...not neceserely will give you a best performance/numbers you expecting from your purchase.
Me in example I did not buy those kits, when I wanted to buy all were out of stock, so I ended up browsing inventories in automotive supply stores. And these springs I am using right now @970 fps/140 bar/33.9 grain in .25 cal. And I can go higher speed but no need for it.
Improvise, try things...don't just buy from shelfs
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I have a very similar setup and and @110bar my impact is shooting the 36.2 slugs @940-950fps . Does your impact have a power plenum?
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just a thought that you should check that the reg pressure gage is correct and not reading low ... good luck
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You hit the nail on the head. The stock FX guage said 160 and I put a digital Sekhmet gauges on it. Well I'll be damn the reg is now showing me 132bar and creeps to 135 sometimes. So FX gauges suck.
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