Bullet weight variations

Presuming they are from the same lot, what would the expected/acceptable variance be using a comparitor to measure from the base of the bullet to a point on the ogive?
 
I don't know exactly. When I measured Sierra 150-grain 0.308" MatchKings from base to comparator intercept with the ogive, I got an extreme spread of 0.008", and those bullets shot fine.
 
cdoc42; yes .032 diff will indeed cause poi shifts. and if you loaded to overall length rather than base to ogive length your harmonics also change, in effect you changed the jump to lands. by seating that way.
 
George, I think you are correct, but just let me add that if I didn't realize there was a 0.032" difference in bullet base-to-ogive, and my seating die was set to seat a 0.538" B-to-O bullet at 0.02" jump, my next bullet, perhaps being 0.570 B-to-O, would change the jump.
That is not the same procedure as seating everything to "overall length" (case base to bullet tip) but the net effect would certainly be as you described.
 
This one is tricky. The seating stem "mouth" has certain diameter, and its position in the press is fixed. The variations in b to o doesn't necessarily imply the same variation in bullet jump per se. It should be less than b to o variations, I think.

Anyway the step size I use for tuning seating depth is 0.003". I probably would like to sort b to o variations to similar order of magnitude.

-TL

Sent from my SM-N960U using Tapatalk
 
tangolima; yeah there are a lot of variables involved. some seating die plugs are made with a very sharp cone and some with a dull one. my rcbs 243 seating die only touches about the last .060" of a 107 smk while it contacts about .125" down on a 105 amax just looking at the two bullets you wouldn't think there would be that much difference.

i was speaking in general and not specific. i don't have any rem 130 psp to look at so i can only generalize.
 
cdoc42; oddly enough, not every factor will affect things as expected. case in point (pun intended) i loaded a few bullets backwards just to see while firing groups of 10 at 100 yds if i could tell which one it was... first group i couldn't the entire group was .743" and no key-hole. if asked before i tried it, i would have guessed the poi shift would be an inch or more. subsequent group one was a flier.
and seeing that i don't believe in fliers it had to be seated backwards. still only half an inch low from the rest though.

but at longer ranges yes you can tell. without a doubt.
 
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