Read somewhere that the N90 is too hard (?).Bought mine, 113 and 016 in 70 hardness, from Amazon for about $7 for each in 100 count per pack.These respective sizes are for the 17xx and the Disco.I use MAP hammer springs on my Crosman/ Benjamin builds.
It was part 012. It was only on the on pistol hat it caused issues.
I have a combo of 70, 90 and urethane o rings in my guns since they all produce a different amount of compression or rebound from the hammer strike. Don't be afraid to experiment with different hardness o rings. FYI, You can change o rings by simply removing the trigger assy and rear cap with spring and use a pick to fish them in and out, no need to remove barrel/shroud assy.BD
Quote from: WildCJ5 on April 11, 2021, 10:28:16 AMIt was part 012. It was only on the on pistol hat it caused issues.Hi. Could I just ask a little bit more about removing this part?I had a few shots with mine yesterday and pretty sure I have clipping, most likely down to this part.As this centres the barrel within the shroud, are you using enything else to do that, or is your barrel now running free floating within the shroud ?Thanks
Quote from: buldawg76 on April 12, 2021, 02:39:35 AMI have a combo of 70, 90 and urethane o rings in my guns since they all produce a different amount of compression or rebound from the hammer strike. Don't be afraid to experiment with different hardness o rings. FYI, You can change o rings by simply removing the trigger assy and rear cap with spring and use a pick to fish them in and out, no need to remove barrel/shroud assy.BDThanks for the tip.I certainly don't want to be disturbing the TP seals too often
Quote from: robs5230 on April 12, 2021, 05:41:26 AMQuote from: buldawg76 on April 12, 2021, 02:39:35 AMI have a combo of 70, 90 and urethane o rings in my guns since they all produce a different amount of compression or rebound from the hammer strike. Don't be afraid to experiment with different hardness o rings. FYI, You can change o rings by simply removing the trigger assy and rear cap with spring and use a pick to fish them in and out, no need to remove barrel/shroud assy.BDThanksWhere do you have the power set and what sort of shot count are you achieving?Thanks for the tip.I certainly don't want to be disturbing the TP seals too oftenYea with trigger and rear cap/spring out just open bolt so hammer slides to rear of tube and remove/install o rings and measure valve travel with gun degassed for starting point of tunes.I use a urethane o ring against the valve then play with 70 and 90 duro o rings for the remaining 3 to fine tune the curve to my liking.BD.
Quote from: buldawg76 on April 12, 2021, 02:39:35 AMI have a combo of 70, 90 and urethane o rings in my guns since they all produce a different amount of compression or rebound from the hammer strike. Don't be afraid to experiment with different hardness o rings. FYI, You can change o rings by simply removing the trigger assy and rear cap with spring and use a pick to fish them in and out, no need to remove barrel/shroud assy.BDThanksWhere do you have the power set and what sort of shot count are you achieving?Thanks for the tip.I certainly don't want to be disturbing the TP seals too often
I am shooting at 12 fps levels with AA10.34s going out at 715 fps. I was getting about 35 shots with the bstaley mod but have since installed a reg in my 1720 so I now get 45 shots per fill at the same power level. If I remember correctly my hammer spring setting was around 3 or 4 turns from fully CCW and stroke was about the same from fully CCW as well so start with hammer at 4 turns CW and stroke at 3 turns CW from fully CCW to see where you are at. Then adjust stroke to get desired fps/fpe in middle of pressure range ( 2500-2000), then back off CCW hammer spring till fps/fpe starts to drop in same pressure range and once it drops add 1/4 to 1/2 turn CW back to hammer spring and you should be close to best setting.. Then run full string to see how the curve plots and also watch to see where the fps/fpe drops significantly to determine low pressure end number.Then fill and enjoy. Every gun is different so it may take some experimenting to fine tune.BD
Start and end pressure? Back the throw out just a tad more and lean harder on the hammer spring. A stiffer hammer spring tends to work better with the mod. I used a cut down discovery spring that worked well. When tuned well....it shouldn't really burp until the shot string starts dropping off.Swap in a n70 to get a little more squish with the stock spring.
Im pretty sure i was at .10 before i ended up regulating it.Then went to .110 -.112 after i regulated it. Opened up the valve to match and now get 48 shots at 12 fpe. Crazy how many low power shot that little tube will give.
Quote from: buldawg76 on April 13, 2021, 07:28:07 PMI am shooting at 12 fps levels with AA10.34s going out at 715 fps. I was getting about 35 shots with the bstaley mod but have since installed a reg in my 1720 so I now get 45 shots per fill at the same power level. If I remember correctly my hammer spring setting was around 3 or 4 turns from fully CCW and stroke was about the same from fully CCW as well so start with hammer at 4 turns CW and stroke at 3 turns CW from fully CCW to see where you are at. Then adjust stroke to get desired fps/fpe in middle of pressure range ( 2500-2000), then back off CCW hammer spring till fps/fpe starts to drop in same pressure range and once it drops add 1/4 to 1/2 turn CW back to hammer spring and you should be close to best setting.. Then run full string to see how the curve plots and also watch to see where the fps/fpe drops significantly to determine low pressure end number.Then fill and enjoy. Every gun is different so it may take some experimenting to fine tune.BDBrilliant thanks.THats a good starting point for me, though I'll be looking to set power mid 10's so will hopefully see a decent enough shot count.I reckon I will reg it eventually.Which reg did you install ?
Quote from: robs5230 on April 14, 2021, 04:25:13 AMQuote from: buldawg76 on April 13, 2021, 07:28:07 PMI am shooting at 12 fps levels with AA10.34s going out at 715 fps. I was getting about 35 shots with the bstaley mod but have since installed a reg in my 1720 so I now get 45 shots per fill at the same power level. If I remember correctly my hammer spring setting was around 3 or 4 turns from fully CCW and stroke was about the same from fully CCW as well so start with hammer at 4 turns CW and stroke at 3 turns CW from fully CCW to see where you are at. Then adjust stroke to get desired fps/fpe in middle of pressure range ( 2500-2000), then back off CCW hammer spring till fps/fpe starts to drop in same pressure range and once it drops add 1/4 to 1/2 turn CW back to hammer spring and you should be close to best setting.. Then run full string to see how the curve plots and also watch to see where the fps/fpe drops significantly to determine low pressure end number.Then fill and enjoy. Every gun is different so it may take some experimenting to fine tune.BDBrilliant thanks.THats a good starting point for me, though I'll be looking to set power mid 10's so will hopefully see a decent enough shot count.I reckon I will reg it eventually.Which reg did you install ?Hey RobI installed a Robert lane regulator set to 90 bar and also per his recommendations using the supplied drill bit of 3.5mm opened the valve exhaust port, TP and barrel port to 3.5mm. With a reg you want no restrictions in the port from valve to pellet since you are reducing the plenum size using a reg as compared to an open tubes plenum. General rule of thumb is you want the port from valve to pellet at 75/80% of pellet diameter so 3.5mm/.140" is right in that percentage. Unregged keeping the TP slightly smaller acts like a restriction to help increase shot count slightly.Rod chimed in with the same suggestion as I would give to flatten the curve with 70 o rings and heavier hammer spring. If you can use a stiff enough spring that you can have about .050" of free play between the hammer and spring uncocked and get the fps/fpe you want it will help eliminate any hammer bounce and wasted air. You want the hammer in free flight just before it hits the valve stem with a stiff spring so when the valve throws it back at the spring it cannot rebound with enough energy to reopen the valve.You are getting close it appears. BD