help with ogive measurment and sorting

B

bozo699

Guest
Hey guys,
Need some advice on ogive measurment and sorting them.I have the tools from sinclair to measure your bullet length from ogive.I just want to do some testing for myself to see group size difference between weighing each bullet and sorting as I have done for years against measuring ogive and sorting.To my question I was measuring some 190 smk with about a .007 varience what would you concider max spread .002? I would appreciate any help I could get from you old timers with lots of long range experience.Oh I will start @ 600 yds then 1000Yds.Hopfully this makes sense.Thanks.
Wayne.:confused:
 
Wayne,

Based on measurements that I've done myself, I am uncomfortable with the performance of devices that operate off Vernier calipers.

I did just what you did - sorted the projectiles in .002" increments, then, on the advice of a friend with more pertinent experience, ran the sort again. I found that I was getting up to that sort range variation (.002") & more. Put it down to several variables that accumulated or cancelled each other for any measurement, such as:

  • The consistency with which I closed the verniers on the projectile, the force I lay onto it to close.
  • Any fiddling needed to do to seat the projectile squarely.
  • Swaging caused to the ogive during measuring.
  • The accuracy & repeatability of the tool (my digital claims A=+-.001", R=.0005")
In the end, I segregated only those projectiles that were plus or minus more than .005", which turned out to be less than a dozen of the 1000 200 grain SMKs I tested.

Since then, I've been convinced that the only reasonably repeatable, reasonably consistently method is using one of the proprietary or otherwise devices that measure off a dial gauge with the projectile point down settled gently by gravity in a purpose cut "throat". Sometimes I wonder how much of what we do is because of the warm feeling we get of a job well done.

But then again, that opinion would still leave you well short of the price of a cup of coffee.

John
 
John,
Thanks:) I had to chuckel at the end of your post.I believe your right though I have spent the last 3 or 4 hours messing with these measuring devices with varying results.$20-$170calipers,didnt seem to matter,have a redding comparitor guage it varied as well close but not repeatable.However I used two caliper ogive tools back to back on same caliper,one on fixed blade the other on sliding blade- lined up,put boat tail in one and ogive in the other slide back n fourth several times trying to use the same force.Seems to be working better than other methods. I have a few other thoughts but its getting late will try later,anyway Thanks for your words of wisdom.
Wayne.
 
Wayne,
I use a Bullet sorting stand like the one in tha Sinclair cat. with the black granite base. When I sort the bullets that I make (30 cal) I try to keep them with in .002". I put a bullet in the holder and let the dial indicator put the pressure on the base of the bullet, I turn the holder about one turn and take the reading.
john
 
I guess it depends on what your target is and how far away it is. But for 1000 yards and under, I agree that .002" variation is very acceptable. But if you buy bullets in quantity and are going to be shooting competitive paper, you just as well seat all alike bullets if you can. It's a confidence builder if nothing else.

I also think a double measurement device is a little more accurate than just measuring one way. Two Stoney point comparators on a caliper give more consistent results at 2000+ yards than just using one because they measure more closely to the real bearing surface than just going from ogive to base with one tool. At that kind of distance, .002" variation can give 20" of vertical displacement so it's a pretty good magnifying glass for what is going on. But at 1000 yards, especially for varmints, measuring base to ogive and allowing .002" variation will afford all the hits that no variation will give.
 
Maybe I'm alone in this but I've never seen the need nor experienced any difference in group size as a result of sorting custom grade bullets. I purchased bullets from BIB, Berger, Cheek, and Bart's and all performed at the same high level. Count me as one who grapples with other accuracy projects rather than sorting custom bullets.
 
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