Tuning RTI Prophet Hammer Spring Problem

[Pfddi]

I have an RTI Prophet that was converted into a Performance model. The rifle came stock as a .30 caliber performance. The gentleman that I bought the gun from did the conversion (a great job) and sent it to me along with a .22 barrel installed and the .30 barrel. He put the spring in that came with the performance upgrade kit (gotten from rtiarms.shop site). The gun shot great and I tinkered around with it and then changed out the barrel to .30. With the spring in it, it would barely shoot at all and I cranked it down to almost the end to get any shots at all. So I changed out the spring with the one that came with the stock Prophet and I could barely get the screw in as it was so tight. Now just the opposite occurred: The hammer spring screw extended more than 3/16ths out from the butt plate! And it was hard as hell to cock. I then got the .22 lr barrel and put it in along with the original screw and it is back to working great except for the fact that the hammer spring screen is really cranked down. I have included a picture of where I have it to push JSB redesigneds at 970 fps.

I have also included a picture of the 2 springs and you can see the length and and spring size difference. What I wanted to do was to cut down the heavier spring sot that I could use it for both the .30 caliber barrel as well as the .22 barrels and just make adjustments to get the speed/fpe that I want. Has anyone else done or had to do this before? Is there a better solution than cutting the larger spring down and grinding it flat to match the way the springs are now? Unfortunately, I also get a lot of air noise in my right ear on every shot. Thanks.

 

[Mrshosted]

If I’m understanding you right, it sounds normal. The Prophet 2 doesn’t have a heavy hammer. It extremely lightweight , it uses speed from the spring to open the valve. Completely normal to have the adjuster in 1/2 to 3/4 of an inch. You may need to raise your regulator pressure for the .30 to get the speeds you desire.
As for the air blowing, there’s a oring under the set screw that holds the barrel in. You mention you changed the barrel. Did you remember to put the oring in. Or maybe it was damaged and/or needs to be replaced. Air likes to blow up the thread and into your face if you don’t. Theirs is a up dated set screw that helps sealing.

 

[Pfddi]

Thanks @Mrshosted - I have a Prophet 1, not a 2 that has been converted so are you saying that I have a Prophet 2 now? I thought there were differences between a converted Prophet 1 and the new 2. But I did raise the regulator to 200 to get the .30 to work at all with the light spring, with the spring turned down all the way save for maybe one revolution.

Thanks on the oring under set screw! I will definitely check that out - especially since it is all apart now!

 

[customcutter]

If I’m understanding you right, it sounds normal. The Prophet 2 doesn’t have a heavy hammer. It extremely lightweight , it uses speed from the spring to open the valve. Completely normal to have the adjuster in 1/2 to 3/4 of an inch. You may need to raise your regulator pressure for the .30 to get the speeds you desire.
As for the air blowing, there’s a oring under the set screw that holds the barrel in. You mention you changed the barrel. Did you remember to put the oring in. Or maybe it was damaged and/or needs to be replaced. Air likes to blow up the thread and into your face if you don’t. Theirs is a up dated set screw that helps sealing.

I'm glad I checked this thread. I have a Prophet 2 .22 caliber. I bought a used .30 barrel for it, and when I received it I pulled the .22 barrel and inserted the .30 just to check the fit. Then I put the .22 caliber barrel back in. I recently started noticing a puff of air when shooting. I didn't know if it had done this all along and I just noticed it. It sounds like it might be due to the set screw and o-ring. I'll have to check it out. Thanks for posting.

 

[Pfddi]

I checked the o-rings on the barrel and they were both in tact and good shape - the barrel is new. I will get some new ones and replace them none the less as I have had to do that on some fill probes that did not have a lot of use but the o-rings went anyway. O-rings are one of the "OpExs" of PCPs!

 

[Scotty1]

For what it’s worth, I ordered 90 duro barrel to receiver o-rings, to replace the 70 duro stock o-rings. The thought being that the firmer rubber may help with the pop in my ear I get at higher power tunes. I haven’t pulled my barrel to change them yet, but shared some with another member and he believes it helped. I’ll report back with my findings when I know for sure. I didn’t have this problem with my Priest 2, but perhaps the rear block is slightly different size-wise.

 

[Scotty1]

Pfddi, as far as you hammer springs go, maybe check the bottom of the hammer, where the spring sits, there may be a shortish, maybe 1/4” long aluminum spacer sitting in there, which can be removed. Removing the spacer, would allow room for the heavy spring.

 

[Pfddi]

@Scotty1, here's what was in the back of the hammer spring. It doesn't seem to have enough width at the bottom to really make a lot of difference if I leave it out. Since I have 2 of the new, heavier springs, I thought t wouldn't hurt to cut and grind one down to see if I could find a happy medium. On the o-rings I was thinking the same thing as you have already done! Do you know the size and I will order a few (I think 100 minimum for a couple bucks) and give it a try and report back? Sorry I did find out the o-ring: 1.5mm x 12 Buna-N 90

 

[Scotty1]

Yeah, that’s a hammer weight, mine was just a spacer.

 

[Pfddi]

Already ordered from the same store! Thanks!
I do have the end piece (part 60 in the blow up) that came with the original .30 caliber barrel, but when I changed to the heavier spring, I put the longer one back in thinking that it was required for the performance versus the smaller one. Don't know it that's part of the problem. I haven't tried it with that short end yet either. Maybe try it without the long spacer and see the results? Thoughts?

 

[Scotty1]

The short one, if I’m not mistaken, is the spring cap from before the adjustable hammer spring upgrade, so not needed. The long one is the hammer weight, needed to open the valve at higher reg pressures.

 

[Pfddi]

I took the barrel off and examined the o-rings. They looked fine, so I added some silicon to them and but the barrel back in. I cut down the heavy spring and put it all back together again. I noticed the the puff of air and sound at the magazine has now gone down. I went out to shoot but some how forgot my Allen keys so I was only getting 880 fps where I normally had it tuned to about 960, so I can't say if the total noise has been reduced. I have the Buna 90s coming and will replace the 70s in order to test again and will report the results.

 

[Pfddi]

As a follow up to the thread, I finally go t to go out again today after a 2nd full hip replacement ( 3 weeks and walking again!). I took the longer, heavier spring and cut off the extra length to make it the same length as the lighter spring that I was shooting before. That seemed to do the trick. I do not have the hammer flush - maybe a turn out and I am at 970 fps with the Jumbo Redesign 25.39 grain pellets ( I have the LW LR 24" barrel in). I am pleased with the results. I will put the .30 caliber LW barrel in tonight and take it out tomorrow and tune it up, but so far I can't be much happier. Thanks everyone for the help and advice.

 

[airgunmike56]

Yea, thinks for the tip Scotty on the Buna 90 0 rings , I going to get my order in..
I guess these fit all the 177,22,25,30, barrels,,,,, Hope so.
Thanks again
Mike

 

[Pfddi]

@airgunmike56 - I have put them on both the 22LR, the regular .22 and the .30 caliber and all fit correctly. I don't have a .177 but would be willing to guess it will work.

@Scotty1 - I didn't go hog wild on the order quantity this time! Just 25 like you.

 

[Scotty1]

@airgunmike56 - I have put them on both the 22LR, the regular .22 and the .30 caliber and all fit correctly. I don't have a .177 but would be willing to guess it will work.

@Scotty1 - I didn't go hog wild on the order quantity this time! Just 25 like you.

Did it, by chance, help with the pop in the ear? My Prophet is shooting so well, I haven’t pulled my barrel to change the o-rings. I’ve been plugging my right ear while shooting.

 

[Pfddi]

@Scotty1 - yes it did help! I also added the white thread sealant tape on the grub screw holding down the barrel and with the 2 I don't have to wear an ear plug in my right ear now. Not as quiet as my Uragan and of course the normal rifles with the receiver in front of the ears, would I like it quieter - sure, but it is way better and I really like the platform. Waiting on ordering the 600mm RPB in .22 for slugs!

 

[Scotty1]

I’m waiting for that barrel as well…I keep getting RTI sales ads, but I want my barrel, not ads. I’m glad to hear the o-rings helped, I love this gun, it works so well, always!