Question about the Impact Mk2 .30
- Thread starter mark404
- Start date
According to UTAH Airguns, the MK2's are tuned to a relative velocity of 850, so just do the math for .30 cal ammo to determine the out of box tuned performance.
That makes for around 70-75 FPE depending on 600 / 700 mm barrel.
You can tune it however to 100+ fpe provided you modify the right parts, increase the pressure, and sling heavier lead.
-Matt
That makes for around 70-75 FPE depending on 600 / 700 mm barrel.
You can tune it however to 100+ fpe provided you modify the right parts, increase the pressure, and sling heavier lead.
-Matt
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Same here, I can get up to 930 by setting the reg to 155bar, but then I start getting reg creep. All stock till tomorrow...
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It's the same as the older impacts! I thought they say it has a bigger plenum, so it should shoot at higher fps.
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Thanks for the replies everyone
I was hoping for low 80's FPE, and it looks like that's attainable without much effort.
Lewis, what are you doing to your Impact?
I was hoping for low 80's FPE, and it looks like that's attainable without much effort.
Lewis, what are you doing to your Impact?
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It's because they have the same undersized 5.5mm valve. I will list mods in order of importance for .30 cal.
1 - Larger valve seat.... this is the greatest restriction.
2 - Elongate the brass pellet inlet port and open the pellet probe larger still or dual port the brass and probe.
3 - Hammer weight... only if you want to exceed 145 bar or if you've installed a substantially larger valve.
4 - External plenum... more plenum = less pressure drop when the valve opens. This mod requires radically modifying the valve housing. Big power gain with a larger valve.
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I have read many times as well that needs a shorter rod spring. Do you have any idea how much shorter? If I remember well Ernest mentioned that rod spring has moved 3” far from rod seal.
Is the only modification I can’t understand so far. Can anybody help us with the right dimensions?
Is the only modification I can’t understand so far. Can anybody help us with the right dimensions?
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You just add a spring seat 3 inches forward of the delrin and trim your spring to match. It may require a slightly lighter rate spring. This helps with airflow but the small valve is the biggest impedance.
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