Marauder Project – .22 Tuning (Part 2)   Leave a comment

After my last post, I went out Sunday afternoon and did a bit more tuning. Well, I end up getting about 20 shots with an average of 840 fps. However, my little 3000psi tank does not grant many fills going to 2800psi. I decided to back things down and perhaps get about 20-25 shots at 800 fps with Barracuda Match pellets.

Also, I noticed inconsistencies in my previous posting. It would seem that I became confused in the wording and what I was turning. On Sunday, I reviewed my notes but alas, I could not figure out what the current settings are.

I decided to start over this evening after work. I decided that I would start at the beginning, review my previous notes, and go from that point. I changed my abbrevaitions for the two adjustments in the rear of the action so as to not get confused again. I will use HS for hammer spring and Sk for Hammer Stroke. The HS is increased by going clockwise (cw) and the Sk is increased by going counter-clockwise (ccw). Thus my notations became [-1 cw Sk], meaning one full turn clockwise on the hammer stroke adjustment. This seemed to help keep thoughts straight on paper.

I found some differences in what the manual said and what my findings were. I moved each setting to the lowest setting, moved up based on previous notes, and began testing. Thus I began with the Sk and resetting it to the bottom. I noted it took 20 1/2 turns to get to the lowest setting. This is more that what I read in the manual and what I based my previous notes on. From the bottom I took 10 ccw turns and shot a Crosman Premier. 789. I added four turns ccw. 948. So I am at 14 full turns ccw from the bottom. This is where I started with the Sk.

For the HS, I counted what was currently being used. At the lowest setting I counted 8 1/4 turns to bottom. I had the gun previously moved 7 turn cw. I decreased by one to 6 and refilled to 2600 psi. 939 fps. From this point, here are my notes. I only used either 1/4, 1/2, or 1 full turns. I also started with Crosman Premiers (CP) as there were only ~25 left.

-1 HS ccw; 905; 901; +1/4 HS cw (5 1/4 total); 910;[Tried one barracuda match, 789]; +1/2 HS cw (5 3/4 total); [Barracuda, 808] CP=938;
*Current pressure, ~2500 psi; CP string – 942, 934, 944, 942, 940, 935, 936, 936, 931, 926. +1/4 HS cw (6 total); 920, 921, 913, (~2000 psi).

==== Refill to 2600 psi ====
912; -1 HS ccw (5 total); 942; -1 HS ccw; 954; (Current, ~2500 psi); -1 SK cw; 929 [Barracuda, 808];

At this point I ran out of CPs and swapped to JSB Exacts. According to ChairGun Pro the JSBs would need to be at about 930 fps. This keeps the desired 30 fpe and easly swapped over to Barracuda Match pellets.
String with JSBs: 892, 902, 901, 903, 908, (@~2500psi), 907, 913, 909, 911, 911, 899, 915, 920, (@~2300psi), 913, 911, 908, 904, 901, 899, 895 (20 shots, Current – ~2000 psi).

I refilled the rifle to 2600 psi and added one Sk turn ccw. I needed the number to come up just a bit. So the current totals are (remember, started from bottom of both), HS = 4 and Sk = 14. First shot… 930. Right where I wanted to be. Now I wanted to back the metering screw down to perhaps tune just a bit more. The metering screw (MS) was set all the way to the bottom (about 4 turns) and then opened ccw 2 1/2 turns. 878 fps. And the last of the adjustments for the day.

+1/2 MS ccw; 916, +1/4 MS ccw; 924; (MS current = 3 1/4 ccw turns); 925, 922, (@~2500psi), 920, 917, (@~2400psi), -1/2 Sk cw.

I am on call this week and was paged. I was on the phone for close to six hours.. so I did not complete anymore testing. I think I am close to about 800 fps for 25 shots with Barracuda Match pellets.

Here are the current totals:
MS = 3 1/4 ccw turns;
HS = 4 cw turns;
Sk = 13 1/2 ccw turns

If I have gotten confused again, let me know. I think I kept it straight this time.
I will refill to 2600 psi and try again tomorrow.. if I have any pellets left. 🙂

Blessings,
Jeff

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Posted April 19, 2010 by avv604 in Marauder

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