I've done a search without anything useful found and am wondering if someone can point me to some tips on how to align the moderator to the barrel to avoid pellets clipping the moderator.
Thanks
Thanks
Looking for tips when pellets seem to clip moderator
- Thread starter sasquatch
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Find someone with a LATHE and concentricity gauge and put a MARK on your barrel or use the TP as a guide if it's at 6 o clock position or 12 I clock barrel set screw. Remove that barrel have him run it on a lathe and check concentricity anf if it's PERFECT it near perfect according to your LATHE worker just reinstall barrel and use the exact size LDC example 22 for your 22 caliber. If its way off then have your LATHE worker mark it on a white tape wrapped around that barrel near your LDC threads the greatest and smallest points preferably as many points as possible you are looking for high thick spits and low thin spots here. Screw on your LDC all the way. Mark your LDC EXACTLY IN REFERENCE TO THAT TAPE ON THAT BARREL. Unscrew that LDC and remove all internal baffles. Drill those internal holes offset to correspond to the markings of that BARREL and LDC. Tricky part here. Reinstall in that exact position that correlates to your markings preferably epoxy permanently. Go and shoot. If it's PERFECT then RED LOCKTITE that LDC onto the threads. Good Luck. Yo!
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Much simpler lazier unsophisticated barbaric way is go plus 1 or more guaranteed 2 sizes bigger if your bore is too way off centered that kinda defeats the purpose but makes it quiet nonetheless but not as silent as it should be as by design. You could use that interesting tape the end of the LDC endcap trick I just read yesterday to see where the pellet is striking and if centered then you're fine otherwise drill it offset towards where it's shooting rivaling your end cap and hopefully you don't need to do the inner baffles otherwise see post above. Good Luck. Yo!
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Fellow member YO does have a point, however I like the KISS theory- keep it simple stupid philosophy and minimizing the headache. If your mod threads on tight and is same caliber as pellet- increase 1 size caliber. Is mod loose? Wrap Teflon tape around barrel thread to help tighten the thread and center the mod.
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Sound level is almost unaffected by bore to caliber clearances. Does the gun shoot well w/o the moderator?
Try turning down the power by 10%. The added Mass of the moderator at the end of the barrel will cause a shift in harmonics.
Try turning down the power by 10%. The added Mass of the moderator at the end of the barrel will cause a shift in harmonics.
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Most likely it's the harmonics of the barrel. Adding weight at the end (the moderator) changes the harmonics; you will most likely also see a shift in POI. Going with a caliber size larger moderator is the easiest fix. Using a barrel band will also help.
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I switched barrels on my Dream Tac from .25 to .22. Just used the same Donny FL FX Brand moderator (for .25) on the .22. Could not get above 625 fps with 15.89 gr JSBs. Tried reg & hammer adjustments and no change. Took off the .25 moderator and got 970 fps! Put on an FX moderator for .22 that came with my Crown and fps stayed the same (970 fps). Any ideas why the larger diameter moderator obviously was clipping, but the .22 moderator wasn't?
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Could be the moderator threads not perfect or internal baffle shifted so might have a chanted baffle partially obstructing clear straight through passage. JUST guessing BLINDLY without ANY pictures here. Yo!
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If you are having a clipping problem, there is a machining error involved. If it is a factory installed moderator, I'd just return it. If it is an adapter that is attached to either the barrel or a shroud, there could be a threading error that is not really something you can fix. The easiest solution, if it works, is to move up a caliber (or two) in the moderator and see if that gives enough clearance. If not, there is enough error involved that something needs to be replaced, hopefully under warranty.
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Is the barrel bore off center? If so, I think going up one LDC size Moderator may be your best option
Are you seeing any clip marks on the moderator? If not, it could be hitting a baffle, or the internals in the moderator.
What brand Moderator are you using? Donny recommends going up one pellet size with his moderators.
Whats the FPS that you are pushing through it?
Are you seeing any clip marks on the moderator? If not, it could be hitting a baffle, or the internals in the moderator.
What brand Moderator are you using? Donny recommends going up one pellet size with his moderators.
Whats the FPS that you are pushing through it?
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In answer to the above questions - I put a .25 Donny FL moderator (made for FX) that came with my Drealine Tac .25, on the .22 barrel that that I installed on that Dreamline Tac. The .22 was getting very low FPS with 15.89 gr JSBs (625 - 650). I removed the .25 Donny and shot with NO moderator on the barrel. FPS increased to 970 fps and shot well. I then put a Crown FX .22 factory moderator on the .22 barrel and it shot fine - 970 fps. The Donny shows no sign of clipping on either end, and a bore light shows no internal damage that I can see. Nothing is loose, no baffling misalignment is visible when looking through the moderator. No noise when I shake it to indicate anything loose.
It works on the .25 barrel but not the .22. I can't figure this one out - the .25 should easily pass the .22 pellet if the .22 moderator does. Only get drop in fps when the .25 Donny is used.
It works on the .25 barrel but not the .22. I can't figure this one out - the .25 should easily pass the .22 pellet if the .22 moderator does. Only get drop in fps when the .25 Donny is used.
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Well, I found this thread with the same problem of a 100 FPS drop using a Donny LDC so its not as a serious drop of FPS as you are experiancing. They are guessing too...
Possible, it is a turbulance issue causing drag?
Is there also a complete loss of accuracy?
https://www.airgunnation.com/topic/fpe-loss-from-the-moderator/
Time to give Donny a call...
Possible, it is a turbulance issue causing drag?
Is there also a complete loss of accuracy?
https://www.airgunnation.com/topic/fpe-loss-from-the-moderator/
Time to give Donny a call...
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This thread sounds like a plausible cause of fps drop. But it is so significant in my case that can't be all. I was truly shocked when it dawned on me to try shooting without the moderator - I had tried adjusting everything else - and my speed became normal. I have not tried that moderator again, but I should just to be certain of the speed drop and to see if it is repeatable. Since the moderator was made by Donny for FX, and was compatible with my .25 barrel it came with originally, I couldn't imagine that was the problem.
Now there is the difference of barrel length. The original .25 barrel is 600 mm and the .22 barrel that replaced it is 500 mm. The Crown that the working .22 moderator came from had a 600 mm barrel, but that moderator doesn't seem to be affected by the shorter 500 mm.
Thanks for the link to the thread, by the way. It does shine some light on the issue.
Now there is the difference of barrel length. The original .25 barrel is 600 mm and the .22 barrel that replaced it is 500 mm. The Crown that the working .22 moderator came from had a 600 mm barrel, but that moderator doesn't seem to be affected by the shorter 500 mm.
Thanks for the link to the thread, by the way. It does shine some light on the issue.
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Hmm, I dont own a Donny, but if possible, I would try shooting the Donny without the internals in it to see if the FPS goes up. If the FPS goes up, then may you find out that the baffles efficiency are responsible for it. just guesing.
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