100 yard shot with my .25cal Marauder

[ztirffritz]

My .25cal Marauder wasn't performing up to snuff. For some reason the speed seemed lower. My recently acquired chrono confirmed what I suspected. I was shooting around 760. Nothing that I tried would boost the speed any higher than 780. I finally found that the breech seal was missing...D'oh! I should have noticed that much earlier. Oh well, I'm still learning...With the breech seal replaced I was scraping 900fps and my shot string looked more like a logarithmic scale than a standard scale. My shot speeds fell off a cliff after about 3 shots. So I set about tuning the gun and hit upon what I think is the sweet spot. I got it to go from 860fps down to 830fps over 16 shots. My buddy was at the range shooting my .22lr next to me. He was packing up because it was time for us to leave. Before we left though I took a pair of shots at one of the targets he'd set up at 100yards. I'm pretty sure that these were pure luck, but he now thinks that I'm a target shooting god! ;-) One drifted a bit to the right, the second was almost dead on. I'll let him think I'm a god for a bit longer. He'll figure it out eventually.

Many many thanks to AJShoots for helping me to get this gun sorted. 

 

[ajshoots]

Good shooting and really happy you got it tuned!! Curious??? Does it start at 860 and slowly drop velocity over those 16 shots or do you have a bell curve?

 

[ztirffritz]

I wouldn't call it a bell curve. I didn't record the actual numbers, but I made a mental note of the general pattern.
I haven't plotted it, but it looks more like this(I'm making up the numbers, but they're close):

1. 845
   [/LIST=1]
   1. 860
      [/LIST=1]
      1. 866
         [/LIST=1]
         1. 864
            [/LIST=1]
            1. 860
               [/LIST=1]
               1. 860
                  [/LIST=1]
                  1. 858
                     [/LIST=1]
                     1. 856
                        [/LIST=1]
                        1. 856
                           [/LIST=1]
                           1. 854
                              [/LIST=1]
                              1. 850
                                 [/LIST=1]
                                 1. 848
                                    [/LIST=1]
                                    1. 844
                                       [/LIST=1]
                                       1. 840
                                          [/LIST=1]
                                          1. 836
                                             [/LIST=1]
                                             1. 830
                                                [/LIST=1]
                                                I can probably make it better, but I'm happy with it for now.
                                                
                                                
                                                

 

[ztirffritz]

I'll also mentioned that we shot the .22lr over the chrono and found a HUGE variation on the speeds. We recorded a shot at 870fps and another as high as 1210fps. We ran about 20 shots over the chrono and I was really surprised. About 1100fps was the average but the spread was wide.

 

[NMshooter]

I almost started dancing with that song LOL. Nice bullseye shot!!!!

Doc

 

[TexasHoosier]

Your curve is in line with mine. Very close. I have a little less drop off in the last two shots. The middle of the string with JSBs (25gr) is running in the mid 860s and each end tails off into the 840s. (25gr). It flattens with heavier pellets. With 31 gr Barracudas, the curve begins around 790, but jumps up to around 805 and sticks close to that until about the 12th or so. I am getting sixteen pretty good shots. With a factory tune it is doing everything as advertised. My only problem has been blowing a couple of breech O rings-which were a few cents a Home Depot. Very happy with the MRod.