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# Bullet Bearing Surface Length Question(s)

#1
03-08-2009, 11:44 PM
 Platinum Member Join Date: Jan 2004 Location: Blackfoot, Idaho Posts: 8,871
Bullet Bearing Surface Length Question(s)

Anyone out there besides GG sort bullets by bearing surface length? (I've emailed GG)

Some one on the 6BR site says sort them to 0.003"

Would that be +/- 3 or an extreme spread of 3?

Also, 0.003" seems a bit anal for a hunting situation vs BR shooting?

Also, my bullets are coming out with the lighter bullets bearing surface lengths of 0.500
The heavier bullets show a bearing surface length 0.0135" shorter than the lighter versions.

Given the 12 grains difference in weight, what's the odds of getting the same velocity from both weight of bullets. Or in other words how much does bearing surface length affect pressure/velocity?

Or should I even give a hoot??
#2
03-09-2009, 12:03 AM
 Platinum Member Join Date: Mar 2007 Location: MN Posts: 1,219
Re: Bullet Bearing Surface Length Question(s)

That's a good question. I just started doing it for the heck of it...but that doesn't mean that it's the right thing to do LOL
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#3
03-09-2009, 07:34 AM
 Platinum Member Join Date: Oct 2005 Location: Michigan Posts: 2,232
Re: Bullet Bearing Surface Length Question(s)

Roy,

I only sort my 338 bullets ( for my Edge and AM), these are my 2 "long range" rifles. Which bullets are you sorting? All the SMK's that I've sorted have not varied by weight at all. If I remember correctly, my extreme weight spread was .6gr for 1000 bullets and was caused by 2 bullets. The extreme spread of the rest was within .3gr.

As far as length, I was sorting into .001" buckets with the SMK's. Not that it was necessary for accuracy (who knows?), but that's just how I sorted them.

What bullets are you sorting? 12gr's seems like a pretty huge spread.

As far as being anal as compared to the BR guys, I would guess that baring surface inconsistency has a larger affect on my 338AM at 1500yds than it does on a bench rester at 100yds.

AJ
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#4
03-09-2009, 01:29 PM
 Platinum Member Join Date: Jan 2004 Location: Blackfoot, Idaho Posts: 8,871
Re: Bullet Bearing Surface Length Question(s)

AJ

I'm sorting Berger 7mm 168s and 180s (source of that 12 gr number) after I squeeze them down to 277.

The bullets are pretty much +/- Zero for weight but vary a bit in overall length.

Bearing surface varies a bit also.

I know that vertical stringing @ LR will appear due to varying bearing surface length.

What I was wondering is what's the odds of approaching the same velocity with both bullets with the 12gr heavier bullet's bearing surface being about 0.013 shorter?

I guess I'll find out when I start shooting....
#5
03-09-2009, 03:48 PM
 Platinum Member Join Date: Feb 2004 Location: Pennsyltucky Posts: 2,630
Re: Bullet Bearing Surface Length Question(s)

generally speaking, what happens is the heavier bullet starts out a bit slower but has a little higher BC. this makes the trajectory very similar. i don't weigh sort my bullets but do separate by BS.
#6
03-09-2009, 05:06 PM
 Platinum Member Join Date: Jan 2004 Location: Blackfoot, Idaho Posts: 8,871
Re: Bullet Bearing Surface Length Question(s)

Quote:
 Originally Posted by davewilson but do separate by BS.
Dave,

#7
03-09-2009, 07:34 PM
 Platinum Member Join Date: Feb 2004 Location: Pennsyltucky Posts: 2,630
Re: Bullet Bearing Surface Length Question(s)

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