measuring distance of bore diameter on bullets.

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philipbrousseau

Member
I don't have a tool to measure bullets base to bore diameter. why would it not be better to measure the bullet in the seater cone distance to bore diameter. i assume base to bore dia. works as that is how its done. but just curious.thanks for your thoughts.
 
what i'm getting at is, if i sort bullets base to bore diameter will the land to bore diameter distance be equal when i seat them in my cases.
 
I'm not sure you understand why you are measuring.
In long range shooting people get concerned about bearing length
Base to ogive or on a boat tail ogive (?) to ogive.
The feeling that different bearing lengths lead to different velocity with the same load.
 
If your seater die doesn't touch the tip of the bullet (touches only the curvature), and the bullets were made in the same die, you don't have to measure anything. Just "black" up a loaded bullet with a Bic lighter, chamber it, remove it and look at it. The seater die doesn't know how long or short the bullet is. It just seats the bullet (cartridge) to a specific length.

The short answer is yes....as long as your seater stem doesn't touch the tip of the bullet. If it does, fix it such that it doesn't.

Quit measuring bullets. If they won't shoot well try something else.
 
The measurements (within a box of bullets) from where the seater stem makes contact, to where a comparitor would make contact, (near to where the rifling would mark a bullet) can vary quite a bit, depending on the manufacturer, and in those cases were there is the greatest variation some sort of sorting can improve the consistency of ogive to case head measurements of loaded rounds, BUT since most of the bullets in the short range benchrest game are hand made, using a single pointing die, this is not much of an issue for that class of bullets. IMO the best way to determine whether you need to measure and sort bullets is to look at the consistency of ogive to head measurements of your loaded ammunition. There are other things besides variation in bullet shape that can cause this variation, so it is important that before you spend money and effort on a fix, that you prove to yourself where the problem is coming from. To the OP...the first thing would be to buy a tool that allows you to measure off of the ogive, near to where the rifling would make contact, to the base of a bullet, or the head of a loaded round's case.
 
thankyou for the comments. ogive to head measurement differences is what i am trying to eliminate. checking loaded cartridges i find distance to land variations and want to sort bullets to eliminate or greatly reduce these differences. i have a bullet comparator but wasn't sure base to ogive length would let me sort to eliminate the different ogive to land differences i get when seating.
 
Before you invest in more equipment, other than an "ogive length checker" I suggest that you try sorting bullets base to ogive to see what effect that has on the ogive to head consistency of your ammunition.
 
And as has been pointed out, ensure the bullet tip is not touching the seater.

Is all the brass the same ?
 
Actually case base(head) to ogive is not really affected by bullet base to ogive.
That is a seating issue, the seating die, bullet shape, case, and press setup.
 
Thankyou all for the suggestions. i will measure base to ogive and check results. i have run into bullet tips hitting the seating cone before and watch out for that and my brass is matched, same lots and trimmed.
 
Gizmo

I made this base length checker for the .30 cal. BR bullets I used to make:

- Turned a piece of Delrin. The 'step' fits into a Stoney Point ogive checker body. Bored the i.d. to .350-ish, stopping short of the entire length of the Delrin:


- Applied some epoxy to the i.d. of the Delrin, some release agent to a bullet and pressed the two together in my lathe. The pic is grainy but you can see how the epoxy formed a perfect match to the bullets forward section:


-Put a hole in the end so the tip of the bullet couldn't interfere with the measurement. You can see the metplat of the bullet down in there:


-Put it in the tool body:


-Zero the dial caliper:


-Measure the length:


You now have a measurement from the base forward for a bullet from that particular die.
 
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