I switched to my 25 caliber barrel on Sunday morning after my 30 caliber started to shoot erratically. It was time for a cleaning, I had put about 800 rounds through the 30 caliber barrel, plus I wanted to shoot my 25 caliber JSB Mark II's to see how my barrel liked them. I set the power wheel to four and the first few fill ups went fine, I zero'ed my scope at 40 yards and found the pellet and barrel combination was returning dime sized groups from a bench rest, with refills after 64 shots. That said, after 64 shots, I noticed that my pressure gage did not drop below 200 bar, but had read that 60 shots was about all you could expect without a drop in velocity.
I wanted to test this so after filling to 250 bar, I shot six magazines (96 shots) with no drop in accuracy. I was at a tad below 200 Bar which, did not seem right. I have not messed with the regular adjustment, it's still at the factory setting of 150 Bar. I got up this morning (Monday) and shot two magazines, accuracy was still perfect, pressure remained at a tad below 200 BAR. I then lowered the power when to MIN and shot a magazine, the pellets dropped about four feet from point of aim at 40 yards, this seemed normal. No movement on the pressure. I called AOA from work and spoke to Rich. He suggested that I remove the air bottle to see if the gauge dropped to zero. I came home tonight and removed the air bottle, the gauge went to zero. Then I screwed the air bottle back on, the pressure went back to where it was that morning. So I then went outside and shot two magazines into the ground rapid fire. The gauge went down by a tiny amount.
I think either my air bottle gauge is broken, or cocking the rifle is not fully charging the gun. Perhaps the gun is only being charged with 10% of what should be going into the gun. I don’t have a way to measure the speed of my pellets. My scope is not adjusted (Hawk Frontier 30 5-30x50) way out to the max on the upper turret – it’s not like I had to turn the top turret to max to get on target, vertical is about half way. The pellet seems to drop normally, my adjustment from 30 cal to 25 cal was not that drastic, if that makes sense.
I wanted to test this so after filling to 250 bar, I shot six magazines (96 shots) with no drop in accuracy. I was at a tad below 200 Bar which, did not seem right. I have not messed with the regular adjustment, it's still at the factory setting of 150 Bar. I got up this morning (Monday) and shot two magazines, accuracy was still perfect, pressure remained at a tad below 200 BAR. I then lowered the power when to MIN and shot a magazine, the pellets dropped about four feet from point of aim at 40 yards, this seemed normal. No movement on the pressure. I called AOA from work and spoke to Rich. He suggested that I remove the air bottle to see if the gauge dropped to zero. I came home tonight and removed the air bottle, the gauge went to zero. Then I screwed the air bottle back on, the pressure went back to where it was that morning. So I then went outside and shot two magazines into the ground rapid fire. The gauge went down by a tiny amount.
I think either my air bottle gauge is broken, or cocking the rifle is not fully charging the gun. Perhaps the gun is only being charged with 10% of what should be going into the gun. I don’t have a way to measure the speed of my pellets. My scope is not adjusted (Hawk Frontier 30 5-30x50) way out to the max on the upper turret – it’s not like I had to turn the top turret to max to get on target, vertical is about half way. The pellet seems to drop normally, my adjustment from 30 cal to 25 cal was not that drastic, if that makes sense.