In my mind, anyhow. Sure, I could get 15fpe with 30 pumps, but who is going to sit and pump a gun that many times every shot? Not me.
Prior to recent work done, I was seeing 540fps at 15 pumps with a 14.5" LW barrel. Now, these barrels tend to have very tight chokes and rob velocity especially on these weaker guns.
Going over the chronograph now, I'm seeing 615fps at 15 pumps, and 540 at 10. Using crosman 14.3gr pellets. Recent work was simply adding a dual seal flat top piston (replacing my brass single seal), and I cut the valve body inlet seal to 1/3 of it's size while also boring the inlet slightly, and installing a pin into the front of the inlet valve to fill almost all of the inlet bore in front of the seal. Raising compression, and wasting less air.
Below is not the pin I used, but is tighter fitting. I left the tiniest bit of play in the inlet bore between the pin. I also made the tip of the pin flush, and a little bit rounded since I had no clue how far into the valve body it would be retracting. Hoping the rounded profile would allow air to pass by it if it were to retract almost all the way out of the bore.
Sorry to re-post the same photos from the other thread, but I simply did not feel like pulling the valve back out of the gun just to take photos of it. I thought there would be some testing and modifications I would need to do, but it's just plain worked. The gun has picked up over 100fps @10 pumps. I'll take it!
Prior to recent work done, I was seeing 540fps at 15 pumps with a 14.5" LW barrel. Now, these barrels tend to have very tight chokes and rob velocity especially on these weaker guns.
Going over the chronograph now, I'm seeing 615fps at 15 pumps, and 540 at 10. Using crosman 14.3gr pellets. Recent work was simply adding a dual seal flat top piston (replacing my brass single seal), and I cut the valve body inlet seal to 1/3 of it's size while also boring the inlet slightly, and installing a pin into the front of the inlet valve to fill almost all of the inlet bore in front of the seal. Raising compression, and wasting less air.
Below is not the pin I used, but is tighter fitting. I left the tiniest bit of play in the inlet bore between the pin. I also made the tip of the pin flush, and a little bit rounded since I had no clue how far into the valve body it would be retracting. Hoping the rounded profile would allow air to pass by it if it were to retract almost all the way out of the bore.
Sorry to re-post the same photos from the other thread, but I simply did not feel like pulling the valve back out of the gun just to take photos of it. I thought there would be some testing and modifications I would need to do, but it's just plain worked. The gun has picked up over 100fps @10 pumps. I'll take it!
Most everything I have is a never-ending project. I still have another valve, so I will be doing some testing with it evnetually, too. I tried using an altered port today with no change in output at 10 pumps. Seems The gun tops out at 650fps. The pressure inside the valve is so much that the hammer is not opening the valve enough to dump it. That's ok. I think I will try and alter this valve volume to be greater, and my other valve I will try to minimize volume to see the difference in power vs pumps.