How do you figure you O.A.L starting point?

[Rule3]

So when I started loading( which was 270 win) my father in-law showed me how he figured his OAL. He took his cleaning rod with a jag that had the point filed flat. He inserted the rod down the bore to touch the bolt face(cocked so firing pin was retracted). With a permant marker at the muzzle end he drew a line around the rod. Next he removed the bolt and lightly pushed a bullet into the rifling. He then reinserted the rod and marked the rod again, this time touching the tip of the Bullet. Then measuring the lines (bottom to bottom) he came up with a max OAL. We set the bullet back 15-20 thousandths to start. Finding the sweet spot.
I still use this process almost 30 years later. How do you do it? What tools or tricks?
Jeff

A homemade "Ranging Rod"

 

[1911art]

I mostly shoot single shot bolt guns so I’m not limited by a magazine.

I seat the bullet with fairly tight neck tension (~ .003”) and long enough in the case so I’m sure it will hit the lands.
I remove the ejector when finding jam and touch lengths . Chamber the dummy cartridge, withdraw and look for marks on the bullet with a 10x hand lens. For my records, when the marks from the lands on the bullet are twice as long as wide I call that jam length. I measure with a comparator and record the col. Then I Gently polish the marks off the bullet with 0000 steel wool. I then seat the bullet deeper in the case ~ 0.005” deeper and chamber again, withdraw, inspect the marks, record col, polish, seat deeper and chamber again. I’m looking for lengths where the marks from the lands are twice as long as wide, then square marks which I call touch length, then I want the length just where there are no marks from the lands on the bullets.
I find this more accurate and repeatable than the Stony point - Hornady tool.
I do this for every bullet brand/type I plan to shoot and record in a book for each rifle. So if I say I’m jumping 0.015”, that’s 0.015” shorter than the length that left square marks on the bullet.
With all the different views and terminology I needed a method that I understood and could repeat.

 

[338reddog]

A homemade "Ranging Rod"

Thats how I do it. I am going to make a ranging rod. Simple design

 

[IWAC]

What trouble have you had with too much neck tension for bolt lift method? I generally use too much on purpose to help reduce how much the test itself will forcefully seat the lands. Only negative consequence I have seen is when a guy collapses the shoulder via repeated, deeper and deeper seating of the bullet. Too little neck tension can also work - as long as the bullet isn’t getting pulled and stuck in the rifling. I measure my BTO before and after the test to confirm the bullet hasn’t been further seated - or at least capture how much.

I split the neck of a cartridge on one side, and oil a bullet to reduce sticking in the bore,p, then chamber and extract gently. several times will give an average, and discard any result that is radically off commonly used COALs. Gotta do it for each bullet used, tho.

 

[Varminterror]

I split the neck of a cartridge on one side, and oil a bullet to reduce sticking in the bore,p, then chamber and extract gently. several times will give an average, and discard any result that is radically off commonly used COALs. Gotta do it for each bullet used, tho.

There shouldn’t be an average to take. That’s the problem with this method. Your lands aren’t moving, so the measurement should not vary.

 

[Toprudder]

I split the neck of a cartridge on one side, and oil a bullet to reduce sticking in the bore,p, then chamber and extract gently. several times will give an average, and discard any result that is radically off commonly used COALs. Gotta do it for each bullet used, tho.

I make some for most calibers that I reload for. Makes it easy when I collect a new gun or a new bullet type.

 

[jhansman]

For my target rifle, I use a Hornady OAL gauge with a fire formed case I sent to them for threading onto the gauge. Using the bullet I will shoot with, I determine the OAL when the bullet is on the lands, and then back off the load about .015-020". This method has given me excellent accuracy over the years. There are several ways to determine the OAL with the bullet touching the lands; I just use the gauge because it's quick and easy.