The Quest for Perfection

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wyshadow

wyshadow

Member
May 11, 2015
1,723
282
Las Cruces, New Mexico, United States
I'm going out of my mind here, and slowly out of pellets. I've had my ProChrono for a year and half now and I never used it until this past month. My gun, 2nd gen marauder .25, was shooting really good when I got it. From what I can remember, I turned the hammer spring slightly up and striker slightly in but I can remember how much (my first mistake;shouldn't have messed with the gun) and the gun was shooting really good. About a month ago, I wanted to know how this gun would do at a faster velocity, so I started tightening the hammer spring and messing with the striker. I really screwed up my gun in the process and I couldn't get it back to where it was (my second mistake; i should've recorded my position). At the time, I was telling myself I should've taking note where the position of the hammer spring and the striker but I don't think that would have help and let me explain why.

Here is the process of how I used my chronograph:
Hammer spring - HS
Striker - ST
start 2800 psi
All 8 shot string
0 is starting position turned counter clock wise until screw stops
I first started at HP-0 and ST-0 then I turned HS up in one full turn increments leaving ST at 0
0 - 713 fps
1 - 764 fps
2 - 803 fps
3 - 842 fps
4 - 865 fps
5 - 895 fps
6 - 910 fps
7 - 925 fps
No change in fps after 7

From what I read, the preferred velocity is about 900 fps so I started my testing at HS-6. The only thing I changed is ST
HS- 6 and 1/8 Lo-910 SD-1
ST - 1 AV-913
Hi-916 ES-6

HS- 6 and 1/8 Lo-903 SD-3
ST-2 AV-910
Hi-914 ES-11

HS- 6 and 1/8 Lo-899 SD-3
ST-3 AV-904
Hi-908 ES-9

At HS- 6 and 1/4 the best I could get is this:
ST-1 AV-918
Hi-923 ES-10
Lo-913 SD-3

At HS-6 and 1/2 turns the best I got was this:
ST-2 AV-910
Hi-913 ES-6
Lo-907 SD-1

After I did test on the HS at higher turns and adjusting the ST, I could see the best position is the one above. The problem I'm having now is I can't get my gun back this position. The closet I could get is ES- 7 and SD-2 and this was with very slight turns to the HS and ST. The only thing I can think of why I can't dial my gun back is because hammer spring must have rotated as I was turning the screw for testing higher speeds or I'm in the twilight zone. Any suggestions?
 
According to AJshoots the hammer springs on the Marauder are notorious for backing out. He suggests that you count the number of turns from out (or in) so you can go right to the spot if the rifle shows variance in shooting. It is easy to loose count when you are tuning. The key is to know the number of turns for the desired fps. He also suggested to me to open that transfer port 5 1/2 turns out from close. This will give you the maximun opening on the transfer port. From there you can adjust only the hammer spring to get the shot string the way you want. I struggled with my .22 and finally gave up and order a HUMA regulator. I just installed a Marmot barrel so I will be tuning it tomorrow. AJshoots (Aaron) is the go to guy to help get a Marauder working correctly. He is a great guy and very willing to help other shooters out. Just talked with him tonight. I was not able to get the desired 28FPE that I wanted and had to settle for just under 25FPE. I may have to change the valve if I want to get more energy. The regulator really helped me get a better chrony string.
Best of luck,

Doc

PS Hopefully we can team up the next time to head to ABQ.
 
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The Striker is the one that has a tendency to backout. The hammer spring adj tends to stay put. The vms adj is a gimmick in my opinion. It can change velocity, but there are more efficient ways to go about it. Note: neither the WAR or Hill aftermarket valves have a vms adj. They are by far the best aftermarket valves available. Coincidence??? I think not.
 
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