reloading

[Tom Thomson]

What's the best way to determine bullet seating depth on a 308? All the reloading books give COL (cartridge overall length) but that ignores bullet shape (spire point, ogive, round nose etc) and variations between barrels on the start of the rifling.
tommyt

[pepper savage 111]

I prefer to take a fire formed spent casing, take a triangle jeweler file and file a hairline slit in the length of the neck, pinch slightly for to provide adequate friction on the bullet, insert a bullet of your choice in the neck, chamber the inert cartridge VERY SLOWLY AND CAREFULLY, pull the bolt back while making sure the bullet doesnt contact anything on its way out, mic the cartridge from case head to ogive.

Sorry for the long explanation but ive never had consistent readings from the various "tools" sold to make this this measurement. The combination of plastic and aluminum on the commercial OAL gauges leaves quite a bit to be desired. My method doesnt cost anything (assuming you have jeweler files)

Let me know if this makes sense to you. I can try to explain it better if needed.

[Tom Thomson]

Pepper
Makes perfect sense to me. I'll give that a try and thanks.
tommyt

[JTCrl]

The maximum COAL in the books is generally to make sure it will feed through common magazines.

[FW Conch]

I don't bother with the slit, so I don't need the jewelers file. I run a fired case into a full length sizing die about 1/32", just enough to hold some tension on the bullet when pushed in with my fingers. Doesn't waste a case. An Ogive measuring tool can be made from a short length of tubing that is slightly less diameter than the bullet.

[pdcullen]

If I understand correctly, the sized casebhods then tube, which is insertedbinto the chamber proud. When then tube hits by he bridling itnpushes then tubing back into the case. The remaining length is your distance to the rifling.

Did I get that right?

[shooterfpga]

Yes and with an ogive tool you can set them at the same depth everytime. Effectively seating them for CBTO and not COAL which is for saami magazine spec. Whereas cbto is for your specific rifle. Measure with every different type of bullet you run in that caliber ie 168gr and 208gr.