What is the best method of finding exact measurements for lands.ex.-.05 off lands?

The way I have done it is to smoke a bullet over a candle, then take a case that has been fried in the gun (not resized) and mash the case mouth enough to hold the bullet firmly. Slide the dummy round into the chamber and close the action. Carefully open the chamber and remove the case and bullet (hopefully), set up seating die using the dummy round and a dial micrometer to adjust the die.

[This message has been edited by DennisF (edited 09-05-2001).]

I've done it that way (using a magic marker instead of a candle) and it's a lot easier to get a Stoney Point OAL gauge and a comparator attachment for your caliper.

Follow the instructions with the gauge, their suggestions really do give you a more precise reading. Use the comparator for all your OAL settings and you don't have to worry about whether a smashed bullet tip sneaked in to throw you off.

Having tried both with the same bullets in the same rifles, I found the magic marker method generally got me closer to the rifling than I thought or desired.

John

There are more ways to do this than you can shake a stick at. The short answer is that the comparator is the way to go.

You knew there was a long answer, didn't you? Since I am cheap, my way is to use the dowel method and/or the "crush seating method".

The dowel method involves taking a case with a bullet that is seated too long and chambering it (or attempting to). Stick a dowel in the muzzle, and mark the point where it leaves the barrel. Remove and repeat without the cartridge in the chamber. Subtract .01.

The crush seating bullet involves pushing the neck of a fired case out of round enough for it to hold a bullet, but not so tight you could not move it by pushing very hard. Smoke the shank of the bullet and seat long. Chamber and carefully remove. Look at bullet, and make sure the bullet did not pull out when removing from the chamber (sometimes lands will act like a bullet puller, goofing you up). If the bullet was pulled, re-seat to the point where the black was not scraped off (as far as the lands pushed it in, before they pulled the bullet back out). Measure and subtract .01.

I tend to use both measurements, one to verify the other. HTH, Dutch.

I use to use both the marker/candle smoke methods, but recently an older benchrest shooter informed me of a way he has used to great success for a long time now.
Firstly he ran a case through his set up sizing die about 10 times, then he trimmed to the desired length. This seem to weaken the neck of the case enough, as to apply just enough pressure to resist the bullet being pulled when chambered.
Then seat the desired bullet long and slowly chamber the dumby round, this produced a tight crush fit. Remove and measure then subtract .010 inch.
This measurement is close to a mild crush, so you now have an OAL maximum to work from.
I tried this method and it worked suprisingly well. The gent that showed this to me, said he had turned an oversize expander ball that he now uses when sizing the case that will be used for the proceedure explained, and now only 1 pass in the die is required.