My first try at tuning the .22 Mrod

[Ribbonstone]

One way to look at it is to look at the best-of-the-best (more about the plateau than the slopes leading up and down).
In the first tune, had about 14 shots inside of 2%.  In the 2nd, have about 20 shots.
In the first, had  3 shots inside of 1%, in the 2nd have  about 10.

[HillGSA]

Ok Tim, I cranked the spring down 1 turn after pumping up to 3100 and was shooting too high so I ccw 1/4 turn and was shooting 329 so that is where I left it.  Here is the 2nd string.

1.   829     21.  853
2.   832     22.  851
3.   833     23.  851
4.   835     24.  844
5.   835     25.  849
6.   833     26.  847
7.   840     27.  847
8.   843     28.  841
9.   844     29.  839
10.  846     30.  836
11.  848     31.  832
12.  848     32.  828
13.  850     33.  822
14.  852     34.  820
15.  856     35.  815
16.  854     36.  810
17.  853     37.  807
18.  859     38.  806
19.  851     39.  796
20.  858     40.  795

859-828=31
31/859x100= 3.6%
Shots 1-32 are looking good

[HillGSA]

On my 1st string I got 28 shots with a 30 spread.
On my 2nd string I got 32 shots with a 30 spread at 10 psi higher average.
This time I shot the dots for accuracy and it seemed I had slightly better grouping at 800 to 820 psi.  I shot the string at 30 yards which is where I have sighted for zero.  It looks like I had about a .5" high to .5" low so a 1" variance in elevation in the full range of psi.  The wind was 10-15 mph so I'm going to try it again before I make any changes.  I think next I want to try a 770 - 800 psi string and see how many shots I get with that setup.  I bought me a better shooting rest yesterday to shoot for accuracy.  I bought the Fieldpod from Academy.  I think I'm going to like it.  It's light weight and very portable and suits my shooting set up.  My wife's tired of me leaving boxes and chairs set up on the front porch for my target practice every day.  I'm going to make a mount for the front of it to mount the chrony to so maybe I won't shoot my chrony.  I'm waiting on my grease to come in I ordered and I'm going to take my gun down and give change O-rings and give it a good lube.  Sometimes it is really hard to cock.  It gets almost all the way back and it seems to lock up.  I want to do some polishing.  I would appreciate any advise on where to start.  And Worm all's good.  We're just all trying to learn.

Testing for the best accuracy at different velocities is a good idea.

Yeah, I should probably get me a nice shooting rest too.
If you do decide to disassemble your rifle, I have a customized valve cap with spring, that I have found to flatten out the shot string more than the ones that came with the Gen 1 rifles ( like the one you have ) and allows for better efficiency, vs adjusting in on the vas. If interested, shoot me an email at:  contacttimhill@gmail.com

[HillGSA]

Don't mean to hi-jack your post, but just got done running my gen 2-22 Mrod across the chrono and with 14.3 CPHP I'm getting on average 828 FPS. Getting 40 shots from 3000 fill on my pump gauge down to 2000 psi. What can I do to increase FPS? I'd be happy with 30 shots per fill if I could boost FPS and FPE using the same 14.3 gr pellets. Again mb4859, sorry for hi-jacking your post.

828 fps av;   What is the Hi and the Lo, of the 40 shot string ?

[wormbobskey]

The low was 815 and the high was 840 through 40 shots. I was able to get my velocity up, but now the bolt is very hard to cock espeacialy at the end. I'm sort of lost here. I did the same tune as my 25, but the first shot string today was in the mid 500's. I started out with VMS@4, HT@6, HS@3. After adjustments I got it shooting in the mid 800's. Like I said, now the bolts is very hard to cock. Am I going to need to take it apart and deburr the insides. After adjustments  the tune is VMS@5, HS@5.5, HT@4.5 with a low of 809 and a high of 885. What can I do to smooth up the bolt short of taking it apart? Is it a forgone conclusion that I'll have to take it apart to smooth of the bolt?

[HillGSA]

The low was 815 and the high was 840 through 40 shots. I was able to get my velocity up, but now the bolt is very hard to cock espeacialy at the end. I'm sort of lost here. I did the same tune as my 25, but the first shot string today was in the mid 500's. I started out with VMS@4, HT@6, HS@3. After adjustments I got it shooting in the mid 800's. Like I said, now the bolts is very hard to cock. Am I going to need to take it apart and deburr the insides. After adjustments  the tune is VMS@5, HS@5.5, HT@4.5 with a low of 809 and a high of 885. What can I do to smooth up the bolt short of taking it apart? Is it a forgone conclusion that I'll have to take it apart to smooth of the bolt?

Gen 2 .22 cal. rifle
Try:
Fill pressure 3000 psi ( using the pump/fill station gauge )
VMS 4 ( make sure to remove the set screw first, make sure the VMS does not move move/turn when you tighten down the set screw )
HT 0 ( fully CCW )
HS 0 ( fully CCW )


Then, adjust the velocity as needed, using the HS ( 1/4" hex wrench )


Try to get a velocity range close to 868 - 900 - 868


If the rifle does not cock any easier, send me an email at:  contacttimhill@gmail.com

[wormbobskey]

I was wondering how to keep the set screw from turning the valve screw. Just snug it up a little? I filed an angled notch in the stock to be able to get to the valve screw without having to take the action out. I've got to get supper started for the kids. Seems they never stop eating. LOL I'll give your recommandations a try tomorrow. I appreciate the help.

[wormbobskey]

Got it all set up, but ran out of light and the chrono wouldn't register the shots. I'll try it as soon as its warm enough to get out.

[wormbobskey]

Got it done today. Used Tim's start out tune. 3000 PSI on pump gauge, 3200 on rifles gauge. First shot was 764 FPS last shot was 889 FPS. Getting around 24 FPE. Got 50 shots from 3200 to 2200 PSI (rifles gauge). Tune is VMS@4, HS@1/2 and HT@0. Bolt is still a little stiff, but is a lot easier to cock then it was yesterday. Shooting 14.3 gr CPHP. At 25 yards shooting sub 3/4" groups. Think it would be a lot better with a better shooter and scope. I appreciate all the help. Any suggestions Tim on smoothing up the bolt? Half afraid to open the rifle up, but will if necessary.

[HillGSA]

Apply moly powder ( lightly ) to the bolt assembly and the inside of the breech, where the bolt assembly slides and to the bottom of the hammer. Make sure the "bolt stud" on both the hammer and cocking bolt are secure.
BP1764S-W  BP2264S-W_EVP.pdf



I have some small packets of moly powder, if interested send me an email at:  contacttimhill@gmail.com