Hi Guys,
I have ruined my 30 Cal Impact after I installed the Power Plenum 720. A bit of history on my gun, I bought it second-hand from a guy who had Ernest Rowe (yes the FX Master) upgrade the gun to Impact II and add his power plenum. He also did other improvements, installed a valve seat that allows more air, and installed a havier hammer and hammer spring.
The gun worked great, had lots of power, and was very accurate when I bought it. But it was a bit loud, especially after I increased the port size on the barrel and the probe that pushes the slug in the barrel. I upgraded to 720 Power Plenum, and I think that was a mistake. If I use the new valve spring C42 that came with 720 Kit, and the new valve stop, the gun will have no power and the slug will get stuck in the barrel. I use the stronger hammer spring that came with 720 Plenum kit and the heavy hammer from Earnest which is heavier than the hammer from the 720 Kit. I also use two washers inside the hammer with the sleeve that adds more weight and help compress the hammer spring further.
After the slug got stuck in the barrel I removed the small valve spring from the valve stop that came with 720 Kit, and I installed the old valve stop with the rubber ball (so there is no valve spring at all in the gun) and it works better, the pressure closes the valve without the aid of the valve spring. With the regulator set at 140 BAR, hammer wheel max, and valve seat close to line 4, I get around 950 FPS with NSA slugs 49.5 gr 0.30 CAL. So the speed is decent but NO accuracy. I get 2"-3" groups at 50 yards...I think the heavier spring compressed to the max and the heavy hammer cause a bit of recoil and that may throw off my shots...I really don't understand why I lost all the accuracy...
I watched Keith's Impact tuning (with Whiskey 68) and a few others but nothing gives me a clue on how to fix my gun. I really appreciate any tips from this group.
I have ruined my 30 Cal Impact after I installed the Power Plenum 720. A bit of history on my gun, I bought it second-hand from a guy who had Ernest Rowe (yes the FX Master) upgrade the gun to Impact II and add his power plenum. He also did other improvements, installed a valve seat that allows more air, and installed a havier hammer and hammer spring.
The gun worked great, had lots of power, and was very accurate when I bought it. But it was a bit loud, especially after I increased the port size on the barrel and the probe that pushes the slug in the barrel. I upgraded to 720 Power Plenum, and I think that was a mistake. If I use the new valve spring C42 that came with 720 Kit, and the new valve stop, the gun will have no power and the slug will get stuck in the barrel. I use the stronger hammer spring that came with 720 Plenum kit and the heavy hammer from Earnest which is heavier than the hammer from the 720 Kit. I also use two washers inside the hammer with the sleeve that adds more weight and help compress the hammer spring further.
After the slug got stuck in the barrel I removed the small valve spring from the valve stop that came with 720 Kit, and I installed the old valve stop with the rubber ball (so there is no valve spring at all in the gun) and it works better, the pressure closes the valve without the aid of the valve spring. With the regulator set at 140 BAR, hammer wheel max, and valve seat close to line 4, I get around 950 FPS with NSA slugs 49.5 gr 0.30 CAL. So the speed is decent but NO accuracy. I get 2"-3" groups at 50 yards...I think the heavier spring compressed to the max and the heavy hammer cause a bit of recoil and that may throw off my shots...I really don't understand why I lost all the accuracy...
I watched Keith's Impact tuning (with Whiskey 68) and a few others but nothing gives me a clue on how to fix my gun. I really appreciate any tips from this group.