JSAR Raptor Tuning Guide and Thoughts

[jmmartinez573]

I Posted this on GTA and thought I would post it here too. Just in case there are any Raptor owners here that need help getting the most out of their gun.



Today I got back out there and put my .25 Raptor through another shot string with new found settings. This has been the best shot string so far and even confirmed the tuning method with another member and it worked for him as well.

Shot String

Start : 3700 PSI
End : 2000 PSI
Reg Set Point : 2000-1950 (Somewhere inbetween there)
Pellet : JSB King Heavies 33.95gr

885
891
887
891
879
891
880
886
890
888
883
886
883
884
886

888
881
885
888
893
874
885
878
880
891
887
880
886
895
883

894
894
886
893
894
885
887
882
878
880
890
877
880
883
874

885
878
878
887
880
885
878
883
877
878
884
872
874

There was also 5 shots on the same fill with 28gr AVS slugs, I wanted to test the FPS with ammo that was more precise weight wise.

955, 954, 953, 951, 954.

Total of 63 Shots.

Stats for 58 shots of JSB's 34gr.
Hi : 895
Lo : 872
Avg: 884
ES : 23
SD : 5

According to the Efficiency Calc. = 1.18 avg FPE/cuin per shot. ( this is assuming the Raptors plenum is 90cc) (I think this was correct.)

Anyways I am very happy with this tune right now. Here is how I got it.

TUNING METHOD

Since this valve is SUPER easy to open, you will find your optimal adjustments in a very small tuning window. Make sure to use very small adjustments at a time. We are talking 1/8 turns of the allen key.

Set Hammer Adjuster where it is recessed into the adjustment range. 2 or 3 threads should be visible.

Turn Hammer Buffer CCW until the gun does not fire.

Increase Hammer buffer 1/8 Turn at a time and fire the gun through chrony.

As you are doing this you will find your gun hits a max fps and if you continue to turn the buffer your velocity will begin to fall. Once Velocity falls turn your buffer back to your max FPS setting.

Now turn your hammer spring adjustment in CW, you will find your velocity increase to a point and then it will begin to decrease. Now turn the adjuster back to your max FPS setting.

Check your hammer buffer settings again now that you have a new hammer spring setting. Use TINY adjustments CW or CCW and just double check your buffer setting is still optimal.

Shoot over the chrony and see if you are hitting your desired FPS. If not, adjust regulator up or down until you hit desired power level.

I have not tested if changing regulator pressure requires you to re-adjust hammer and buffer settings. I'm ASSUMING that if anything needs to change, it should only be TINY adjustments.




ADJUSTABLE REGULATOR

I don't know if this will be the same for everyones Raptor, but for mine I feel my gun is MOST consistent when I fill to only 3600-3700psi. Any higher than this and my Extreme spread widens.
The reason for this is my regulator pressure will actually be 100 psi HIGHER when my bottle pressure is 4350-3900 psi. My first 10-15 shots will have higher velocities. Once my bottle pressure reaches
3600 psi or so, my reg pressure reads what I set it to. From 3600-3700 psi down all the way to 2000 psi my gun maintains a nice extreme spread for my uses.

I am still very happy that I can use 1700 psi worth of air and get 65 shots at 58-60fpe.


If I ever increase my regulator pressure to 2500psi + again I will revisit the idea of filling to 4350 psi.



There is not very many people putting out info on the Raptor even though there are so many out there. I hope this guide helps those who are trying to get theirs dialed in still.

Tuning the Raptor is unlike any gun I've tuned before. Big Learning curve and not for someone wanting a turn-key rifle. But if you enjoy the tuning process this gun will put your skills to the test lol. NOT for beginner pcp owners.


Raptor Saga Continues!

 

[mtnGhost]

Great write up! That string looks much better than before, glad you got it dialed in so well

I have had a very easy time so far tuning my Mini, but it only has a 17" barrel. For me, it's been real simple: adjust the reg for the ammo I'm shooting. The longer the barrel, the more fine tuning comes into play. Hopefully I'll have those problems sooner than later lol

 

[jmmartinez573]

The problem tuning for me is not realizing how easy it is to over dwell the the valve. 


Within a 1/2 turn of the hammer spring adjustment here was my findings :

12oclock - hammer strike too light

3 o’clock - hammer strike increasing FPS.

6 o’clock - too much hammer strike FPS decreasing. 


this is just an example. 

 

[Springrrrr]

Please describe, "until the gun does not fire". When you back off the hammer adjustment screw ( the one you refer to as the hammer buffer ) there is a point that is reached where the sound you hear is a PFFFT instead of a snap of air. Is that the point you mean, or are you going CCW beyond that point?

 

[FelixS]

Thanks so much for this, I was waiting for a detailed tuning guide as I have never turned a screw on my Raptor - yet.

Any chance of getting pictures? Seriously, I don't know what I'm doing

 

[jmmartinez573]

When I say turn until the gun does not fire, I mean to turn until you can fire the gun with no pellet in the chamber and it sounds like no air is coming out. 


this is only a starting point though, to ensure whoever is reading these instructions that they are starting from the minimum and working their way to the max. 

 

[E30_S50]

Thanks for this! I just received mine today. I'll use this as a guide