Originally Posted by PowellSixO
Ok thanks. What I did was, I took a once fired case and cut a slit in the neck. This allowed the case to just hold a bullet (but also allowed it to slide up and down in the neck). I would put the round at 3.750" and chamber the round. Then I would extract it and measure it. This allowed the bullet to touch the lands, stop, and slide back into the case. I did it 20 times. About 15 out of the 20 times it measured exactly 3.425". The other 5 times it was off by .005" + or -, and that may have been because I bumped the round when extracting it. I feel this is a fairly accurate way to measure my COAL for a round that's just touching the lands. An old timer told me how to do this. What do you guys think?
If you measured from the base of the round to the tip of the bullet then you still don't know what the measurement is from the base of the bullet to where the bullet contacts the lands at the ogive.
One more time, this is why you need a bullet comparator. This lets you measure from the base of the bullet to where the ogive contacts lands. The distance from the ogive to the tip of the bullet can vary at least 0.005" from one bullet to the next. Measuring overall cartridge length is not accurate enough to allow you to load cartridges with bullets consistently touching the lands.
There is no need to cut a case to do the test you did. Take a fired case and a bullet will just fall into that case. You will need to flatten the case neck a little to make the bullet stick a bit. I put magic marker on a bullet so you can see where it slid into the case when you chamber it. If it slides back out a bit when you eject the cartridge this shows up in the magic marker as little scrape marks.