Tuning Prophet performance .30 issue

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madeintheuk

madeintheuk

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Apr 19, 2020
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Washington depot, Connecticut, United States
I recently acquired a prophet performance in .30 cal from a member here on the forums. I got to shoot it today, and I’ve noticed a good blast of air at the back of the rifle (not 100% sure where from) when firing off a shot. It’s very loud (even with a ronin fitted), and I feel is robbing velocity. 
I replaced both transfer port orings on the barrel, and the probe oring. Made no difference. 
any ideas? Is this normal? HELP!
 
Probably just running too high a reg setting or too much hammer spring. It seems that people want to set these prophets up for super power. All that air has to go somewhere and the extra air out the barrel end makes it loud. I turned my reg down to 100-110 bar for .22 pellets and still pushing the 16-18 grs to 850 fps in my compact. Start playing with lower reg pressures and hammer spring and you might get to increase shot count and decrease the report.
 
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It’s not out the barrel. It’s blowing back next to the trigger sear. Basically out the back of the Valve where the pin sits out. Is there a seal or oring back there to prevent this? It must seal somehow. I plan on making this super powerful, and rti assured me it’s slug capable. I know very well how to harmonically tune, but this is most definitely a leak. 
 
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There is not a lot of orings back there to check. One on the pellet probe. Check to see of it is not sealing off the barrel very well.
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I replaced the probe oring, and the transfer port orings already. Nothing changed. It’s very confusing. I feel like it’s coming from the poppet where it sits outside the valve housing for the hammer to strike it. There’s no seal there, like the poppet is supposed to just seal itself. 
 
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I would be interested to hear what you find, please let us know what the problem was.
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So far I’ve torn pretty deep and found no damaged orings. It looks that the poppet seals itself to the back of the valve housing and there is no seal. Wondering if the poppet is bad maybe. I have emails in to aoa, and mr. rob. I’ll let you know what I hear. Very confused by it. I put it all back together, and still the same puff of air, and no difference in velocity. Only other problems I’ve found is the regulator seems to either be sticky, or you really have to crank it for adjustment. I adjusted it twice turning the pressure up 10 bar on the gauge. It registered, then when I dry fired a couple times, it settled back to original reg pressure. Not to mention it’s slow refilling, and squeaks when it does. So far I like how simple it is, but it sure has some quirks that need ironing out. 
 
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Sorry to hear you haven’t found the issue yet. Mr. Rob, in my experience is great with responding to emails, you’ll probably hear from him Monday. I’ve heard about the squeaky regs before, but mine (bought used, used very hard it seems) never had it. I did have a creeping reg, and adjusting was as you described, kinda unpredictable for sure. Mr.Rob has since arranged for AOA to send me the updated reg internals, and so far it is working very well indeed. Before the old reg got really bad, I had some shot strings with a standard deviation of 1 fps. and hope the new one will preform as well. Mention your reg problems to Mr. Rob, perhaps he’ll hook you up. How old would you say your Prophet is?
 
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Sorry to hear you haven’t found the issue yet. Mr. Rob, in my experience is great with responding to emails, you’ll probably hear from him Monday. I’ve heard about the squeaky regs before, but mine (bought used, used very hard it seems) never had it. I did have a creeping reg, and adjusting was as you described, kinda unpredictable for sure. Mr.Rob has since arranged for AOA to send me the updated reg internals, and so far it is working very well indeed. Before the old reg got really bad, I had some shot strings with a standard deviation of 1 fps. and hope the new one will preform as well. Mention your reg problems to Mr. Rob, perhaps he’ll hook you up. How old would you say your Prophet is?
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It was purchased new from aoa June of last year. It’s out of the 1yr warranty period, and aoa made sure I knew that. 
 
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So, it came to you with this problem? Try not to be too discouraged until you speak with Mr.Rob. Were the barrel o-rings intact before you changed them out? Also, did you get a look, when the barrel was off, at the transfer port? Just curious if a pellet or parts of one, somehow got forced into it, long shot I know…..does it happen when dry firing as well? Sorry for all the questions. 
 
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So, it came to you with this problem? Try not to be too discouraged until you speak with Mr.Rob. Were the barrel o-rings intact before you changed them out? Also, did you get a look, when the barrel was off, at the transfer port? Just curious if a pellet or parts of one, somehow got forced into it, long shot I know…..does it happen when dry firing as well? Sorry for all the questions.
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Yes, it came to me this way. My first impression was that it was normal, but after putting a ronin on it, and the report didn’t quiet down too much from the 3 section huma I had, I was a little curious. Then I started feeling the rush of air during the shot cycle (or rather paying more attention to it). At first I thought it was the barrel orings, or probe oring. Even though they looked ok, I felt the seemed s little squashed, so I replaced them anyway. The new ones weren’t much different. I did check the transfer port, and yes, it is clear and the barrel is very clean. Yes, the puff is there when dry firing, but less pressure behind it. I looked into it possibly being from shroud blowback, but I don’t see where it could come from the back of the shroud. It feels as though it’s coming out from right behind the trigger sear area. This is directly in front of the back side of the valve housing. The hammer strikes the back of the poppet in this area, so my thought is the poppet isn’t sealing properly to the back of the housing. There is no seal here, it relies on the seal of the delrin poppet to the metal housing of the valve. Is this normal blowback? I can’t see a proper seal being generated from this setup. 
 
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Something is goofy alot of guns don't use anything to seal the poppet stem from some air leak but usually you can't feel it or it doesn't make the gun louder either usually the leaks from that area are very minimal
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Yeah, this isn’t minimal. So maybe a bad poppet? It looks like the valve housing is a machined part of the real block, but I’m not totally sure
 
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I’ve never had my reg adjusted that high, so I have no idea what that sounds like. I’d jack mine up if I didn’t just change the reg out, gonna be nice to it for a while. I’m surprised others have not commented on theirs.
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Noisy reg is a common issue on these. There lots of videos about reg problems including noise. I’ve never put my reg up that high either. In fact, I haven’t moved it much at all, and it hasn’t budged from 150b even after a couple adjustments. I’d really like to get the air leak fixed or figured out before I play with it too much. I might be losing velocity from it, and no even have to move the reg. 
 
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Have you shot it down below reg pressure? I’m curious how your gauges are, do they match as the pressure drops? My bottle gauge reads 50 bar when completely empty, so I wonder what your true reg pressure is. How is your ES and SD?

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Yes, when I took it apart, I degassed it and watched the gauges. Both went down the same. 
 
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