For those that have put the RPB barrel in your Prophet 1, did you find that you needed more reg pressure to get the rounds moving same speeds as the standard CZ barrel with traditional transfer port? I think they messed up the RPB barrel by making the transfer port half the size of the barrel. For a barrel that is 4 inches longer than my 20" CZ, I feel like I have to really push the reg pressure to stay at the velocities that the CZ barrel was making. Looking for a solution to fill in some of the transfer port to make it more like a Huma/FX slug style.
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RTI Prophet 1 with RPB barrel
- Thread starter Joedirt199
- Start date
I don’t know why they did it that way either. I haven’t noticed needing more reg pressure, but wouldn’t be surprised, you may lose a little to the extra void of the enormous TP? My reg stays at 145 and is very rarely touched. If I ever need to replace the reg, I’ll use a straight, non-adjustable 145 bar reg.
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I believe the porting in the block below the barrel is larger on the P2 and 3. Was the P1 a RPB gun? Or did the RPB barrels show up on the P2? I slightly enlarged the porting on my Priest ll when it was my primary slug gun. It’s not a task I would recommend if you are contemplating it for your P1. Your only option is to cut off the back of your barrel and machine it to match the round port CZ.
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RPB barrels showed up around the 2 and 3 releases.
Yeah that had crossed my mind but they machined a flat on the RPB barrel right behind the 2nd oring that stretches about 3 inches. Would be hard to get the barrel to seal on the top with an oring groove. Guess it wouldn't really matter.
Yeah that had crossed my mind but they machined a flat on the RPB barrel right behind the 2nd oring that stretches about 3 inches. Would be hard to get the barrel to seal on the top with an oring groove. Guess it wouldn't really matter.
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Why did you buy a longer RPB? To chase slugs? I can state for a fact that my .25 RPB’s won’t outshoot the .25 CZ with pellets.
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Yeah I have a bunch of .22 monsters and NSA slugs laying around that I thought would benefit from this barrel. Going to try and fill some of the void with JB Weld and use silicon tubing to seal off the chamber and mold the transfer port into more of a circle. I can coat the openings with release agent so if it doesn't work then the JB Weld will pop right out.
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Do you have a theory for why you need increased plenum pressure for the RPB? I hadn’t noticed it, however, the max ammo weight I shoot is 25.39g, and more frequently the JTS 22.07.
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You are dealing with over a 2,000psi burst of air. I don’t think any kind of glue is going to cut it. You don’t want particles after the 2,000psi beating to fall down into the valve.
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With my CZ barrel I never got up over 120 bar on the reg and it made plenty of speed for a barrel that is 4" shorter than this one. I just think there is too much volume in the chamber and not enough meat there to direct the air down the barrel where it needs to go. Don't see any other barrels with this ginormous of a transfer port.
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Probably just time to sell all the heavy pellets and slugs to be done with it and stick with 21 gr and under pellets. Most of my shooting is woods walking for squirrels anyways.
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Yes. For the block port size and the amount of valve dwell on your P1, the gigantor barrel port might not jive. With the P2/3 it’s a different story. Balance valve and bigger block porting has everything in sinc. If you want to shoot heavier, that’s why there are bigger calibers.
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Yeah I guess so. I have way too many .22 to add another caliber. Guess it is time to take some pictures and get some classifieds up.
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It's JB weld. It's going to pop out with or without release agents.
I bought my Prophet performance 1 with the 22lr barrel and decided I wanted a .25 also, so I ordered a.25 RPB and it works perfectly in the original Prophet. In fact, I did not even touch the regulator and it shoots quite well as is.
I see no downside to the large porting on the RPB barrel. Bottom line, A large port supplied by a smaller port is still just a smaller port.
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The prophet block porting is 7 mm,
Prophet 2 and 3, 8 mm.
Earlier priest is 6 mm.
I've 6 RTI barrels, often swapping between the prophet and prophet 2, only time I have any issues with the port sizes in .177 calibre.
Then I have to restrict the block port to 3 mm. Barrel port sizes haven't caused any issues.
The large port on the rpb barrel is to assist closing the assisted valve on the P2./3.
The rpb barrel works great on my prophet original. No complaints or higher reg pressure needed.
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Well there you go. Two people have had no ill effects of the large port barrel on a smaller port gun. Something else must be going on. I have no experience with a .22 RPB but my .25 RPB’s feel tighter when chambering pellets than my CZ did. But these are pellets and shouldn’t require extra reg pressure to get them moving because they have so little bearing surface.
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I know this is obvious, so forgive me, but triple check the barrel o-rings. I changed mine to 90 duro, and have added a couple wraps of tape type dental floss under the o-ring in the past. It’s also easy to slice a piece off if the block sharp like mine was. If the forward o-ring is allowing blow-by, you likely would not hear it.
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The cz barrels are generally a larger diameter, my cz barrels prefer the larger diameter slugs or pellets, the rpb barrel prefer smaller diameter.
RTI barrels are a separate hobby from the norm.
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Ok so went back at it. 108 bar on the reg 20" CZ barrel shooting JSB 18s at 890 fps. Only switched barrels and 24" RPB barrel only gets 850s with same pellet. The pellet did seat harder with the RPB barrel. I noticed my probe oring was half gone so switched that out and got the same numbers from both barrels. Also added floss under the barrel orings to tighten the interface between the barrel and the receiver. I will slug them next to get an idea of the bore diameter.
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