Marauder custom shop regulated rifle question?
I purchased a regulated .177 cal Marauder custom shop gun with regulator. I am quite familiar with tuning these guns but am a bit perplexed with this one. As per my conversation with tech support at crosman the reg is set at 2000psi. This should be more then enough to get the power levels I am looking for. I am looking to get 875-890 fps with 10.3gr AA or JSB pellets. I've tried every combo of adjustments making sure the TP is all the way open. I can't get the velocity over 855-860fps. The regulator is not adjustable as per the tech person also. Any ideas?
I have the same custom shop regulated Marauder. My regulator is set at 1500 psi. I used my chronograph to measure the speed of 80 shots and every 10 shots I looked at the manometer (pressure gauge) for the pressure reading. When the velocity dropped greater than 12 fps, that is when I know the shots are no longer regulated. I get 75 shots with Crosman 10.5 grain domed pellets from 3000 psi down to 1500 psi at an average velocity of 875 fps. I get faster velocity from JSB 10.34 grain domed pellets.
I agree, a 2000psi setpoint should be plenty to get a 10.3gr moving at 900fps even if the porting is fairly anemic. I’m not familiar with the guts of the regulated Marauder but it would be strange indeed if the porting were smaller than a conventional Marauder since it is designed to operate at lower pressure.
If you happen to be familiar with the report of an unregulated Marauder that has been tuned to a similar velocity, can you comment on how your regulated one sounds? It should be a bit louder because of the lower pressure and longer dwell. If instead it is noticeably quieter, that suggests an issue of insufficient hammer strike…perhaps partial valve lock or something amiss with the trigger group that is affecting the hammer’s acceleration, or potential galling of the hammer in the air tube.
I have to do more testing because the gauge on the gun and the gauge on the tank don't quite match. But I'm thinking its set at around 1400-1600 psi. That still should be plenty of pressure to get to the velocities I'm looking for. The other thing I'm not real happy about is the tech dept told me there were no external adjustments, bummer.
As I suspected the regulator is not set at 2000psi like the tech support told me. Looks like it is set very close to 1500psi. Still plenty of room to push a pellet faster then it is. I checked alignment between barrel, transfer port and valve and everything looks fine. I'm going to put in a slightly larger transfer port and see what happens.