BTO vs ogive to seating stem

[broncman]

Those of you who sort by ogive to seating stem , do you find that base to ogive matters?
I just machined a comparator that uses my seating stem from my seating die and measures that to ogive.

I have heard that bearing surface or BTO makes less of a difference when you can insure all rounds are seated to the same ogive depth.

Thoughts?

 

[Coolhand]

I was batching 155 .30 Cal projectiles base to ogive then seating and then checking seat depth with a Redding instant indicator. For the life of me I could not figure out why after batching the seating depths varied and sometimes by as much as 0.005''.

Google provided the answer and I thought "why didn't I think of that". So I am in the process of doing the same Broncman, making a suitable comparator that will sort from ogive to seater stem position. I am not concerned whether a projectile is seated a couple of thou deeper than the previous one as long as I can get the ogives all within 0.001" of each other and at the seating depth that my barrel likes.

I tried to purchase a Bob Green Comparator but his Bank would not accept my Banks Check so I am messing around with machining one ( well actually a buddy, is with a suitable alcoholic inducement ) I already have a suitable dial indicator so it will be interesting to see if the project bears fruit.

Mike.

 

[BoydAllen]

If you have a micrometer adjustable seater, you can seat all of your bullets a little long (measured on the ogive, near where the rifling would make contact), sort them into like groups, and then adjust your seater for each group to produce uniform from head to ogive measurements.

 

[vinny]

Theoretically, all other variables being equal, the more consistent your match bullets are the better they group but if your seating depths aren't identical (as humanly and measurably possible) then all your work sorting means nothing.

 

[broncman]

I sorted 3 lots of Berger 185 Jugs. First I sorted by base to ogive and was surprised at the difference. One lot was old and the others were some I got last summer. The earliest lot was .015" shorter base to ogive! That was what made me want to check seating stem to ogive.

Weight was very consistent and lengths within the same lot were consistent as well.
When I checked all of them with the comparator I made, they were all within a thou or two! Even the shorter lot was the same. So the variation is either in the base or bearing length.

In 400 RDS I only had a few that were not within .002 stem to ogive, even with big differences in base to ogive.

 

[vinny]

I sorted 3 lots of Berger 185 Jugs. First I sorted by base to ogive and was surprised at the difference. One lot was old and the others were some I got last summer. The earliest lot was .015" shorter base to ogive! That was what made me want to check seating stem to ogive.

Weight was very consistent and lengths within the same lot were consistent as well.
When I checked all of them with the comparator I made, they were all within a thou or two! Even the shorter lot was the same. So the variation is either in the base or bearing length.

In 400 RDS I only had a few that were not within .002 stem to ogive, even with big differences in base to ogive.

Sort using the same tool, seat your bullets using the same tool, have fun shooting. You're usually going to find deviations within a certain lot of bullets. The reason could be different amounts of lube different size cores perhaps different core seating pressure or point-up die pressure by the manufacture. As long as you sort the bullets and they're all within a couple thousand you're good to go.

 

[fm1947]

I think it depends on the bullets, I use base to ogive ,some lots of Sierra have given me three different lengh's but Berger seems more consistant from lot to lot, when I use a BIB or Cheeks they are always consistant from base to ogive

 

[michaelnel]

I bought one of the Bob Green bullet sorting comparators, and going through a couple hundred Berger 105gr 6mm Hybrids was an eye-opening experience for me.

 

[fm1947]

what did you find with the Bob Green sorter

 

[michaelnel]

Up to .006 variation. The outliers there would likely hose up a good group.

After sorting them, I used the Hoover meplat trimmer and pointing die. I betcha they are gonna shoot pretty good now.

STD DISCLAIMER: "If I do my part"

 

[fm1947]

how much was that tool

 

[michaelnel]

how much was that tool

Not cheap. Extreme high quality tool though, a pleasure to use.

http://greensrifles.com/New_Products.html

 

[fm1947]

very nice, not bad with out indicator I'm sure it's a standard hole size to use other indicators, I saved that page for further possible purchase it depends if I get my ass kicked in taxes

 

[broncman]

I am sure the Bob tool is nice and was the inspiration for mine. I just could not stomach the price when I had the ability to make my own on the lathe. Plus I wanted to use my seater stem from my seating die.

I believe this tool should be in every serious shooters bag of tricks!

 

[michaelnel]

I have no lathe or the skills to make such a tool, so purchase was my only option.

 

[fm1947]

I use the hornady tool comparator and redding micrometer dies , those dies seat from ogive, my rounds according to the hornady tool and my digital calipers never vary more than .001from ogive to case head, once I seperate my bullets

 

[broncman]

I also have the Redding micrometer die for 308 . Mine does not seat from the ogive. Can't say as I have personally seen a seating die that seats from the ogive.

 

[michaelnel]

I also have the Redding micrometer die for 308 . Mine does not seat from the ogive. Can't say as I have personally seen a seating die that seats from the ogive.

By "Redding micrometer die", do you mean the Redding Competition seater? Those DO seat off the ogive, in fact they even have a special seating plug (I have one) for seating the Berger VLD and Hybrids, and the reason that plug is offered is that the ogive shape is so much different from most other bullets.

 

[fm1947]

Yes as michaelnel they do seat from ogive I can't remember if I had them semd me the other insert or if it came with two , but I also use a Forster mic die on my 30 br and I never have any issue with any of my calibers, 6br ,223,308,30br

 

[fm1947]

I called redding a few minutes ago to verify what I told you and yes the competition die seats from ogive, he said if you added a mic to one of the other dies that could be an issue and the only other way would be if the seater plug has split then of coarse as you seat it would spread.