My rifle is an FX Impact M3 700mm sniper spec with plenum, power block, tensioned barrel and dual port dumbed down to .177 caliber. I am pretty much limited to .177 here in my country, so I naturally want to shoot the heaviest slug in .177 for maximum damage when hunting for pests in my farm.
I have had good success in tuning for NSA .178/15gr slugs, easily adjust between 900-1050 fps, reg at 100 bar, macro 13, micro 3.5, valve 3.5-4 lines, very efficient air use, nice one dime grouping at 25 yards. However, for the life of me I can’t get good velocity with the heavier NSA .178/20.5gr slugs. The absolute max velocity I could get was 850 fps and I had to max out everything to get it with reg at 135 bar, macro 16, micro 5 and valve fully maxed out, even a slight reduction on setting would drop it drastically to lame 600-700 fps and it consumes air like a leaking balloon…
What can I do? I am targetting 925 ish fps. I asked the shop and he suggested changing hammer to tungsten and spring too but I am not convinced because as far as I know much heavier tungsten wants 170 bar on reg and there is no way I need 170 bar just to launch a puny .177 / 20.5 grain slug to a proper velocity… Currently I am far far away from maxed out shooting 15gr at proper velocity, there is no way I need to upgrade to tungsten just for 5gr heavier slugs?? Maybe I just missed something??
Please advise and thank you very much in advance!!
I have had good success in tuning for NSA .178/15gr slugs, easily adjust between 900-1050 fps, reg at 100 bar, macro 13, micro 3.5, valve 3.5-4 lines, very efficient air use, nice one dime grouping at 25 yards. However, for the life of me I can’t get good velocity with the heavier NSA .178/20.5gr slugs. The absolute max velocity I could get was 850 fps and I had to max out everything to get it with reg at 135 bar, macro 16, micro 5 and valve fully maxed out, even a slight reduction on setting would drop it drastically to lame 600-700 fps and it consumes air like a leaking balloon…
What can I do? I am targetting 925 ish fps. I asked the shop and he suggested changing hammer to tungsten and spring too but I am not convinced because as far as I know much heavier tungsten wants 170 bar on reg and there is no way I need 170 bar just to launch a puny .177 / 20.5 grain slug to a proper velocity… Currently I am far far away from maxed out shooting 15gr at proper velocity, there is no way I need to upgrade to tungsten just for 5gr heavier slugs?? Maybe I just missed something??
Please advise and thank you very much in advance!!
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