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G20 10mm Longshot loads

Discussion in 'Reloading' started by Dlid, Dec 7, 2015.

  1. Dlid

    Dlid

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    I've been working up Longshot, 200gr Zero FMJ, CCI 300 primers, 1.260" OCL, Starline brass 10mm loads for a Glock 20 with Lone Wolf 5.2" bbl. Started at 7.2 grs (Hodgdon start load) and worked up .2 gr at a time to 8.2 gr (Hodgdon max load). Brass looks good - no cracks, primers not flattened, normal Glock rectangular primer extrusion, expanded to 0.428". I finally got my Oehler chronograph up and running and chronoed the loads this weekend. 1265 fps! And, it was about 25 degrees Farenheit. That seems way faster than I should be getting. Also, I now have some concerns about what this Longshot load would be like in the summer at around 90 degrees. Any suggestions?
     
  2. fredj338

    fredj338

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    You are running almost 1" more bbl, certainly tighter chamber, sounds about right. I get almost 1200fps in a stock G20 with the same powder charge & Extreme 200gr.
     

  3. orangeride

    orangeride

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    My 10mm longshot loads run much hotter when it's cold.
     
  4. fredj338

    fredj338

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    That would tell me LS is reverse temp sensitive. I haven't run tests on it, but then it isn't my fav 10mm powder.
     
  5. Dlid

    Dlid

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    I emailed Hodgdon about LongShot and whether or not it is reverse temperature sensitive, but no reply so far. So I did a test this weekend. I loaded up a bunch of 200 gr jacketed 10mm bullets with 8.2 gr of LongShot. Let some get cold (around 25 - 30 degrees) and kept some warm in an insulated cooler with hot water bottle (around 85 degrees). Fired 10 each over the chrono and the difference was only a few fps. So, for this test at least, it seems that a range of 25 - 85 degrees doesn't have much effect on velocities.
     
  6. fredj338

    fredj338

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    Then that isnt reverse temp sensitive. I did a test on WST, my fav low vel powder. It is rumored to be inv temp sens, I found out it is. My test was rds in a cooler with ice, rds left in e sun for an hour & ambient air temp that day of 80deg. The swing from 40deg to over 120deg was about 50fps. So one would get into trouble loading close to PF in the winter & then showing up to shoot a match someplace in 100deg summer day.