Measuring OAL to ogive?

[jasonco]

Back in the old days there weren't any of the wonderfull tools that we have the option of buying today. Yet proper OAL was important even then.
So what was done was to take an empty and unprimed case, and seat a bullet long, and then insert it into the gun and close the bolt. That would seat the bullet by jamming it against the lands.
Next step is place it in the die and turn the seating stem down to touch the seated bullet, then back off and turn it in a turn or so deeper.
Remove the round from the press and use a match to smoke the bullet only. Then reinsert the round back into the gun and look for rifleing marks on the bullet. Continue to turn the stem down and reinsert
the resmoked bullet until the marks barely go away.
Keep the cartridge as a gauge for that bullet for future die settings. Nothing to buy as nothing is needed. Use calipers for deeper seating depth from the touching depth just established.

I use the new tools for this, but I still have my candle & candle holder close by on my bench, to double check.

 

[esshup]

Another measurement that I'm checking is how long the bearing surface is. (i.e. the part that actually contacts the bore) I think the longer that is, the more resistance to being shoved down the barrel, and the higher resulting pressure. BUT, now you have me thinking about ogive to base because that will change the internal case volume once the bullet is seated if the ogive to base is different bullet to bullet.

 

[Gord0]

As others have said, it will give you an area that you can repeatedly measure. The .3 cal bushing should be .3" diameter. Due to production tolerances that will vary slightly. That will tell you where on the bullet is .3" diameter. That won't tell you where your bullet will touch the lands which are at .3". The reason it won't is there is also a lead cut into the chamber, along with the bullets ogive profile.
Find the lands using some of the methods described above, or with the Hornady length tool and then measure with the bushings.