Luger colleagues,
Blue Dot is listed among only four powders for 9mm, 115 gr. jacketed bullets in the Lyman reloading manual and it is at the top of the list in the Speer manual. The 7.0 grain load fills the case to the point of bullet seating. In my experience this is the lightest load with a 115 gr. bullet that will cycle a Luger and the same bullet / powder combo also works in my C-96, 1902 Colt, and 1912 Steyr Hahn. It does require a good crimp for complete burning.
I am hardly a ballistics expert but my theory about the wider variation in velocity and holdopen problems is that despite the crimp, the reduced friction of the coated bullet causes it to start out of the case earlier, resulting in irregular burning of the powder. There is also the problem of the polymer coating not sticking to the bullet very well. Next time at the range I should recover bullets shot into some soft material for examination.
Other brands of bullets may work better and a different powder may work better. I have 50 unloaded polymer coated bullets left. I will send them to anyone who wishes to continue this experiment with other powders.
KFS
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