Coal or ogive

[RemingtonShooter]

I'm kinda new at this and this may be a stupid question. But when loading for consistent loads, due you rely on measuring coal or length of base to give? I have found a few loads I like. I start with coal but heard after that is settled then switch ogive for the specific bullet you are using?

[Gene]

Bullet tips can vary considerably, so that OAL measurements will always be inaccurate. Its OK to check them from a reloading manual, but use them only as a guide.

Measuring from the case bottom to ogive start is much better and more accurate. Get a Hornady OAL guage and read the instructions. You need to find the bullet depth where you can first see the rifling on bullet, then move back from there. Do this with a dummy round (no powder or primer). If your bullets touch the lands, you might try to extract a loaded round and find the bullet stuck in the bore, and powder thru the action. Not good when you are on a hunting trip.

[Aussie Hunter Steve]

The only real justifications for being concerned with COAL is;
1. that the cartridge must be short enough to fit into the magazine and feed properly
2. that the bullet is seated deep enough to be held securely in the case neck.

If these criteria are met there is often an accuracy advantage when having the bullet seated close to the rifling lands.
A simple method is to seat a bullet approx caliber depth into an empty resized case (satisfying #2 above) and chamber the round. As the cartridge is chambered slowly the bullet hits against the lands. You will feel the resistance as you gently push the bolt home and close it down. The lands will usually seat the bullet deeper into the case. Then remove your 'test round' which shows the seating depth for that particular bullet to hit the lands. This 'test round can be put back into the reloading press and the seating die turned down to contact the bullet. Next, turn the seating die down slightly more to seat the bullet a little off the lands. Take the 'test load' now, and with a permanent marking texta, colour the bullet all around in the area where it will first contact the rifling. Chamber the 'test load' again and upon extraction look for any rifling imprints in the texta colour. If there are none you have clearance. Many rifles shoot their best when seated so that the rifling will just imprint the texta yet not mark the bullet. This process needs to be repeated for each bullet you try. Good luck!