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Powder lot numbers-vs-point of impact?

RembrandtRembrandt Member Posts: 4,486 ✭✭
edited June 2006 in Perry Shooter Competition Shooting and Reloading Forum
Maybe I'm being too picky, but is it possible the point of impact can vary between lot numbers of the same powder?
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Comments

  • Tailgunner1954Tailgunner1954 Member Posts: 7,734 ✭✭
    edited November -1
    POI, pressure, and velocity can, will and does change between lots of powder. There is a tolerance on powder, just as there is with everything else. Figure +/- 5% variance from average.

    Remember the bit about "whenever you change a component, back down and work back up again"? Different lot#'s constitute a component change.
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  • perry shooterperry shooter Member Posts: 17,105 ✭✭✭
    edited November -1
    The powder that we can buy for reloading is "canister" powder and is made so that loading manuals can be used to load with this NUMBER/NAME of powder . Most commerical ammo is loaded to a set pressure. Now the rub powder between lots can and does change. My experance has been mostly with 45 ACP and mostly with "Bulls-EYE" powder as far as point of impact my distance is fairly short 50 yards and done with ransom rest and cronograph but group size and Velocity do change between lot numbers The old BULLS-EYE I used 35 years ago was light green and now it is gray. The older powder that I kept for a bench mark will produce 800 FPS with 200 grain bullet with 4.1 grains the new BULLS-EYE takes 4.5 -4.6 for the same 800 FPS this could translate to different point of impact at long distance.
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  • JustCJustC Member Posts: 16,056 ✭✭✭
    edited November -1
    yes,..I marry canisters that are different lot numbers. This way, all I have on hand will burn the same after being mixed.

    Just run the first few over the chrony,.if the MV goes up or down, adjust accordingly.
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  • RembrandtRembrandt Member Posts: 4,486 ✭✭
    edited November -1
    Suspected that may have been why the POI was coming up different....guess I need to buy powder (same lot number) in larger quantities. Thanks for the replies.
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  • JustCJustC Member Posts: 16,056 ✭✭✭
    edited November -1
    Keep in mind too, that if it older, even if it is still quite good, it will burn faster. As the coatings deteriorate over many years, I find the burn rate to increase slightly.

    If you have a few rigs using one powder in common, buy 8lb jugs and tweek the loads for each one all from that one jug.
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