RTI Prophet P1 .22 Efficiency & Power question?

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obi123

obi123

Member
Jan 16, 2023
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Vietnam
Hi guys,

Coming from M3 owner, I've bought a used prophet P1 and was pretty impressed with the low profile design. But the max power and efficiency is poor compared to my M3 (of course) and even my DIY gun.

So normally I noticed that M3 has 20-23mm hammer travel and relatively light hammer 19-24gram depends on your power settings or after market mods.
Even my DIY PCP that has 22mm hammer travel with traditional valve & 24gram hammer has much better efficiency compared to my P1

M3: 1.35 Cubic inch / foot pound of Energy shooting 27gr at 960fps out of 24inch barrel (shot count: 58-60)
DIY gun: 1.2 CI/FtLbs shooing 27gr slug at 930fps out of 20inch barrel (shot count: 50)
P1: 0.9 CI/FtLbs shooing 27gr slug at 940fps out of 24inch barrel (Shot count: 35-38)
All in .22 cal

Upon inspecting the gun internal, I found out that P1 has heavier hammer (31gram) and much shorter hammer travel at only 11mm, which makes high power delivery much more difficult and poor efficiency.

So my task is to modify the gun to increase hammer travel and improve power, reduce cocking force, and get better efficiency.
Is that the right way to go, the hammer travel route?

1703269092307.png
 
Increasing stroke is not usually a good strategy for improving efficiency, at least not as a standalone variable. Why? Because more stroke means more momentum. More momentum means more dwell…and dwell is the property that tends to produce poor efficiency. Either excess dwell or hammer bounce, or both. And a heavy hammer is also more prone to bounce.

Assuming the cocking effort isn’t already borderline too much, you may want to first look into simply reducing the mass of the hammer. Either by removing material from it or by making a replacement from a lighter material. I don’t know where you are on the DIY spectrum but a lightened hammer does not have to be pretty to be effective. An angle grinder and some files and a can-do attitude is sometimes all that is needed.

Another option is to look into a bstaley hammer buffer, which is just a stack of O-rings placed against the back of the valve that acts like a bumper for the hammer to limit lift and dwell as well as help prevent bounce.
 
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Or you can just shim your poppet return spring. I have been a RTI guy since they invented their first gun. When I made my Priest ll into a slug gun, I started playing with the valve spring. I never worried about efficiency because I have a compressor. But with slugs I had to because of dirty air. My third RTI is a P2. A M3 has nothing on it in the power department. Bar for bar on the reg, my M3’s have nothing on it power wise. Actually maybe less. You increase hammer travel, you can increase harmonics. All guns including Impacts with mass moving down a tube after you pull the trigger is not good. I try to minimize everything. Weight and travel.
 
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I don't know where you are, but if parts are available I could machine whatever you want off the hammer, or possibly make a new one for your use.. I prefer to have a sample because I hand fit..
I don't have digital readings so it is measure and turn and polish..
pm me if it is something you want help with..
I'm old, slow and disabled, so I don't do anything quick but I do get it done..
Merry Christmas
Mark
 
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Here's another thought ... Inside the hammer, on the Gen 1 I believe there is a 2nd HS weight, beneath the spring inside the hammer, if my foggy memory is accurate? Perhaps that is missing? Yes the HS is stout on these guns and perhaps someone before you removed it hoping to detune and making the spring lighter which likely didn't help your low velocity numbers?
 
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nervoustrig said:
Increasing stroke is not usually a good strategy for improving efficiency, at least not as a standalone variable. Why? Because more stroke means more momentum. More momentum means more dwell…and dwell is the property that tends to produce poor efficiency. Either excess dwell or hammer bounce, or both. And a heavy hammer is also more prone to bounce.

Assuming the cocking effort isn’t already borderline too much, you may want to first look into simply reducing the mass of the hammer. Either by removing material from it or by making a replacement from a lighter material. I don’t know where you are on the DIY spectrum but a lightened hammer does not have to be pretty to be effective. An angle grinder and some files and a can-do attitude is sometimes all that is needed.

Another option is to look into a bstaley hammer buffer, which is just a stack of O-rings placed against the back of the valve that acts like a bumper for the hammer to limit lift and dwell as well as help prevent bounce.
Click to expand...
Thanks for the advice.
But I really feel like this gun is not producing near as much as it should compared to my DIY gun with 24gram hammer, lighter cocking, shorter barel, same projectile & pressure. I think a 31gram hammer, stiff cocking force, longer barrel like Prophet 1 should produce higher power output at the same efficiency.

For me right now, getting the same efficiency as my DIY gun would be considered successful. I've tried lighter hammer, stiffer spring without any success. They simply too light to bring out any power and will require much more cocking force to gain the same speed.

The reason I've mentioned stroke (hammer travel) is because it's the only thing that is far too different from my other gun. Increase valve spring tension or shimming valve for what I though would only further reduce power. I could say that because I'm not even close to plateau when tuning the hammer.
 
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igolfat8 said:
Something is wrong if you are only getting 35 shots on a 300 bar fill. My P1 would send a 25.4 MRD at 970 with a 145 reg setting I easily got 75 shots.

BTW, The LR barrel is a slow twist 1:32 designed specifically for MRD pellets and if you are wanting to shoot slugs this is NOT the barrel for you.
Click to expand...
I'm filling to 220bar, shooting 27gr slug @930fps out of fx superior heavy barrel, 1:16 twist. How heavy should the hammer be in your P1? Thanks mate!
 
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Vetmx said:
Or you can just shim your poppet return spring. I have been a RTI guy since they invented their first gun. When I made my Priest ll into a slug gun, I started playing with the valve spring. I never worried about efficiency because I have a compressor. But with slugs I had to because of dirty air. My third RTI is a P2. A M3 has nothing on it in the power department. Bar for bar on the reg, my M3’s have nothing on it power wise. Actually maybe less. You increase hammer travel, you can increase harmonics. All guns including Impacts with mass moving down a tube after you pull the trigger is not good. I try to minimize everything. Weight and travel.
Click to expand...
P2 is a beast no doubt. It has the balance valve and very light hammer. By my P1 just has traditional valve so I dont think it can match M3 in terms of power. But I love my P1, holds zero much better than my M3.
 
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igolfat8 said:
Here's another thought ... Inside the hammer, on the Gen 1 I believe there is a 2nd HS weight, beneath the spring inside the hammer, if my foggy memory is accurate? Perhaps that is missing? Yes the HS is stout on these guns and perhaps someone before you removed it hoping to detune and making the spring lighter which likely didn't help your low velocity numbers?
Click to expand...

I have two Prophet Performance Gen 1s - with .22 and .25 long range barrels.

The P1s have a delrin spring guide that goes inside the hammer - it weighs very little. I’ve sometimes removed it to “shorten” the hammer spring without cutting it. This helps if wanting to shoot lower velocities with lighter pellets (15.89g etc)

My P1 hammers both weigh 30.65g

My stock hammer springs measure 2.63” long. Outer diameter is .38”, inner diameter is .24”.

I’d agree that something is off with the original poster’s rifle. My P1s make effortless power - I can get 150 shots with .25 cal shooting 25.4g at 900fps - reg at 100bar - and only filling to 250bar.

With reg at 170bar, you can shoot .22 MRDs at 1,070 fps - still getting around 50 shots.

-Ed
 
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Still curious about the regulator in the P1 pictured in post #1. It does not appear to be a standard RTI model.

The adjustable regs have the twin gauges side by side and their non-adjustable ones have a single gauge.

The regs from Huma have two gauges in a “V” configuration.

The one in the picture appears to have the gauges at 180 degrees to each other.

If your P1 is second hand, maybe the regulator is an off brand and the source of low shot count and power issues.
 
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lbc_PSI said:
Still curious about the regulator in the P1 pictured in post #1. It does not appear to be a standard RTI model.

The adjustable regs have the twin gauges side by side and their non-adjustable ones have a single gauge.

The regs from Huma have two gauges in a “V” configuration.

The one in the picture appears to have the gauges at 180 degrees to each other.

If your P1 is second hand, maybe the regulator is an off brand and the source of low shot count and power issues.
Click to expand...

Yep, you’re right - not an RTI or Huma. If it was my rifle, that unknown reg is exactly where I’d start my troubleshooting.
 
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lbc_PSI said:
Still curious about the regulator in the P1 pictured in post #1. It does not appear to be a standard RTI model.

The adjustable regs have the twin gauges side by side and their non-adjustable ones have a single gauge.

The regs from Huma have two gauges in a “V” configuration.

The one in the picture appears to have the gauges at 180 degrees to each other.

If your P1 is second hand, maybe the regulator is an off brand and the source of low shot count and power issues.
Click to expand...
Im sure the early RTI regulator was that setup.
From memory it was a good regulator.
 
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Vetmx said:
I had RTI’s first adjustable reg. It was a junker. Wound up going with their fixed reg and just shimming them for pressure adjustments. I’ll look to see if I have a pic of my second Priest that came with the gen 1 creepy slow responder.
Click to expand...
Thx for the info on the V1 adjustable reg. Did not know that existed.

The mystery continues though.. If you look closely at the post#1 pic, the reg gauges line up in the same plane. The V1 reg has the gauges offset.
 
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lbc_PSI said:
What type of regulator is on the P1..it doesn't appear to be RTI?
Click to expand...

It's a huben cricket regulator, pretty reliable one. My RTI failed and couldn't find parts locally so I machined an adapter to fit that reg into my gun.

EPG said:
I have two Prophet Performance Gen 1s - with .22 and .25 long range barrels.

The P1s have a delrin spring guide that goes inside the hammer - it weighs very little. I’ve sometimes removed it to “shorten” the hammer spring without cutting it. This helps if wanting to shoot lower velocities with lighter pellets (15.89g etc)

My P1 hammers both weigh 30.65g

My stock hammer springs measure 2.63” long. Outer diameter is .38”, inner diameter is .24”.

I’d agree that something is off with the original poster’s rifle. My P1s make effortless power - I can get 150 shots with .25 cal shooting 25.4g at 900fps - reg at 100bar - and only filling to 250bar.

With reg at 170bar, you can shoot .22 MRDs at 1,070 fps - still getting around 50 shots.

-Ed
Click to expand...

I have no issue with pellets but with slugs, I feel that the gun is working hard to produce 55ftlbs (27 grain .22 shooting around 940-950fps). And yes, if I fill up my gun to 250, then I'll get 50 shots. But that's not the point I'm making here. Just out of curiosity why my DIY gun could bring out nearly as much power with shorter barrel (fx superior heavy 500mm) while P1 struggles with longer 600mm barrrel, heavier hammer at lower efficiency. I have a scuba tank and compressor so filling up is not really an issue, just want to optimize my gun.
 
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