velocity deviation question

cowdoc

January 31, 2003 13:28

i reloaded some 22-250 shells with 36 grs of varget under 55gr nos bal tip,win large rifle primer in win case i got a 49fps deviation to large for my liking! i weighed each charge to same weight for each case. i would think that the dev shouldnt be that large..is my scale not accurate enough? it is a rcbs 50-2 or is varget that way ect ect?....the chrono is pretty new to me havent got to use it much. any ideas
thanks
doc
on edit i only did two shots and extreme spread is 70 fps so my deviation
is not accurate

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  SilverBox

  January 31, 2003 13:46

  50 fps doesn't seem that unreasonable.. What were you expecting?

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  queeksdraw

  January 31, 2003 16:41

  If I were shooting a 800 fps round I might think somthing was up, but for a bullet traveling at the velocity you are shooting I dont think 50 fps is a bad spred. Are you using mixed brass? Have you tried same lot brass. Do you crimp? Look at crimp pressure for uniformity. Dont let your powder set in the hopper over night when you are done put it back in the can. Give it a gentel tumble befor you load the hopper to turn it over and make it uniform. Just my opinion,good luck.
  
  You'v gota kill it to grill it

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  roysha

  February 01, 2003 04:28

  Are you talking about standard deviation or extreme spread? Two entirely different things. For extreme spread that isn't too bad (given the velocities involved). For standard deviation that is a somewhat more that I would want.
  
  BEER IS PROOF THAT GOD LOVES US AND WANTS US TO BE HAPPY!

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  cowdoc

  February 01, 2003 06:23

  i edited the first post as i was wrong the extreme spread is 70 fps i only shot two shots so not very accurate reading of deviation ...i need to do a better test sometime

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  richbug

  February 01, 2003 09:33

  Had the rifle just been cleaned prior to shooting the first shot. If not there will be a great difference in velocity for the first 5 or 6 rounds until the trace amounts of oil are burned out. "fouling shots". Varget gives me the least variation of any rifle powder that I have ever tested. I competion shooting with handguns, guys will shoot recently cleaned guns with oiled barrels, to get velocity up in order to make major power factor with ammo that is not quite hot enough.
  
  Why does everyone feel the need to burn that much powder?

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