I have noticed an apparent variation in the location of the ogive on the same lots of factory bullets. If I measure seating to the lands I get a difference of about .005" using a premium bullet like a Woodleigh or a Swift A-Frame and I don't find that very disturbing. But when I measure a bullet like a Remington Core-Lokt I get up to .03" difference. Is that a typical finding for a low cost bullet?

Yes, even when measured over the ogive, bullet length (or ogive position) varies. I can't tell you whether .03" is an extreme value, but .005" for a big game bullet certainly does not seem out of the question.

The Core-Lokt is a bulk product, you may be seeing bullets made on different production "lines" (dies etc) end up in the same box.

I attempt to react to varying ogives by ensuring they are all off or all in the lands. I don't want the variation of some being off and some in the lands. So the ogive variation becomes one factor in determining where I want to seat my bullets. Yes, even when all are off the lands, there will be differences in the distance to the lands, but you can't get rid of that unless you are willing to sort your bullets for ogive measured length.

- mike

I use Nosler Custom Competition and Sierra Matchkings in my 223rems. A friend suggested I sort the projectiles by length using my Bullet Comparator. I must admit I was surprised to see the variatons that occurred in the base to ogive length. Whilst there wasn't a great variation there were variations. I ended up with 4 -5 lots before I got 20 the same.

Hey Wallace, It is easy enough for you to set-up a Test to compare a 2-3 shot group at each end of your measurements.

I'll guess as long as you are using a Load developed with the never improved upon Creighton Audette Method, and that you use a slow steady consistent Seating Method, that it will be difficult to see enough dispersion from the normal Group to matter at all.

One of the HUGE Keys to repeatable precision accuracy is Seating the Bullets so they are all the same Ogive-to-Land distance. It can not be verified by checking OCL. It must be done by checking the Ogive-to-Casehead distance, or simply relying on the "Seating Stem" to do the job properly with a slow steady Seating stroke.

I simpy rely on the Seating Stem to do the job and have quit concerning myself with measuring the Ogive-to-Casehead distance.

Best of luck to you.

Thank you all for your responses. Can you tell me more about the Creighton Audette method or where I can read about it? Thanks

quote:

Originally posted by Wallace Gaye:
... Can you tell me more about the Creighton Audette method or where I can read about it? Thanks

Hey Wallace, That would actually be the "never improved upon" Creighton Audette Load Development Method. You will understand why it is so highly regarded once you use it a bit and see where the Harmonic Nodes begin to Cluster the Bullets - with relatively few shots.
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Just had a buddy in Califoney tell me last night he opened a new box of 30cal 180gr Sierra ProHunters and the Ogive location was vastly different from his "older" boxes of them. Sierra is normally very consistent, but Forming Dies do wear out and Profile Changes are made from time to time by all the manufacturers.

But, if you try converting OCL to ODL you will find many benefits from doing your Seating this way.

Best of luck to you.

using 2 caliper mounted comparators, you should measure BEARING SURFACE LENGTH. That is the measurement that matters. The seating die, working off of the ogive, will keep the ogive the same distance from the lands with each loading. The difference will be in tip length variances, and the bearing surface length differences which will affect neck tension with the longer and shorter pills that are outside the avg length.