Just got my 30 cal running with a new TJ's barrel. Longer twist rate. I like it... Bottled of course.cheers,Douglas
Quote from: PakProtector on October 17, 2020, 08:03:57 PMJust got my 30 cal running with a new TJ's barrel. Longer twist rate. I like it... Bottled of course.cheers,DouglasGlad to see you posting, I had developed a bit of concern.Please do tell us about the 3 groove slow twist siren.
Bumping this thread for an update.Decided to swap out the modified hill valve for the cothran valve. Also swapped out the tp from .234 to .25ID. Same reg pressure of 170bar. Swapped out the 12lbs spring for the oem spring. Also removed the hill depinger.FX 44.8grHammer tension all the way out- 998fpsHammer tension 1/4 turn in- 1087fpsHammer tension 1/2 turn in- 1070 fpsWow what an increase here. It is using up quite a bit more air then before. Shot count will definitely be down even with the 500cc bottle. I need to get some slugs to test out and tune.This is just initial testing. More tuning to come.Recap of specsOld: 910 fps at 170 Bar Regulated with 44.75gr20" barrelModified Hill Valve.234 ID Barrel porting .234 ID TP12# Hammer SpringJsar HammerHIll depingerNew: 1087 fps at 170 Bar Regulated with 44.8gr-20" barrel-Cothran Valve.234 ID Barrel porting .250 ID TPOEM Hammer SpringJsar Hammer
As I was tuning, I experienced no valve strike. The hammer drops but no air expels. Further inspection found the peek striker cap adhesive gave out over the 1000's of shots thru this build and came off the striker face and was preventing the hammer from hitting the valve stem.I went ahead and left the peek face off and reinstalled everything. Velocities with the FX 44.8 grain averaged 998 with a 3 FPS spread. I messed around with both the hammer tension adjustment and striker adjustment and I was unable to get the previous 1080 FPS + velocities. I'm not sure why since the only change is removal of peek striker face. I did notice a slight puff of air after each shot so the tp is not sealed 100%. Perhaps this slight loss of air is costing me the 100fps? The tp is compression fit so after the teardown, I should have cut a new tp.Or perhaps it was a false reading and I'm chasing a ghost now. After today's tuning here are the numbers with the ammo I have on hand.FX 44.8- 998 fpsJSB 50.15- 962 fpsHybrids 44.75- 979 fpsMore testing with NSA slugs soon.Haven't even mounted the scope back on yet so accuracy testing wasn't checked today. Just tuning over the chrony.
Yes I agree. I adjusted the striker distance each direction without any noticable fps change with the Cothran Valve. I have cut a new TP but haven't had time to test yet. I also got in NSA slugs and Varmint Knockers slugs to test.