#### Walt-Cen

##### New Member
Hi guys, I have a question regarding bullet over all seating length. I thought that the measurement was taken from the bolt face side of the cartridge to the where the projectile touches the lands which is a constant never changing length. however the fellow in the link below says that it is made up of two lengths, from the ogive to the shoulder to the bolt face. If the shoulder on the Honady modified cartridge isn't bumped up against the chamber's shoulder why should any thing els matter?

There could be no shoulder at all, the distance from bolt face to lands would be the same.

By watching this video I have become confused with what I feel are unnecessary calculations, but he seems to attract a lot of prays which makes me feel like I'm missing something.

I personally don't use the Hornady tool, I have made my own and drilled and tapped a once fired case to measure my oal.

If anyone has watch this and understands it perhaps it could be explained. Thanks.

regards to all

Walt

#### 9ptbuk

##### Well-Known Member
Walt, Thanks for sharing the Video . My take away from the video was to use a case that has been fired in the gun and modified for the OAL gauge like you said you were doing .

#### IDelkhunter

##### Well-Known Member
So glad to see this post....been beating my head against the wall lately. I have been making my own cases as well, but have recently discovered that I need to size the body without touching the neck to get it to fit cleanly in the chamber and stop consistently. Which leads me to wonder about the affect of bumping the shoulder on the measurement? Common sense would tell you to bump it to the same headspace with the same die set up the same way, but I am finding .003-.004 difference between some of the fired cases and .002-.003 on sized cases. Making several modified cases with different headspace measurements shows significant variation in CBTO measurements.

Can someone help me with my logic here?.....

Thanks,

Marcus

#### maninthemaze

##### Well-Known Member
Great question??? Now you've got me wondering about my COAL. I've been using the Hornady kit but never thought about the distance from the ogive to the bolt face. The Hornady kit indexes off the shoulder of their brass and doesn't allow for the distance between their brass and the bolt face. Using a fired brass would help, I think I'll just use the head space comparator tool and measure some fired brass vs their COAL brass and add the difference to my numbers.

Here's another good video to figure out COAL

http://www.longrangehunting.com/forums/f120/video-lrp-diy-seating-depth-98286/

#### tbrice23

##### Well-Known Member
I make and tap my own cases from once fired brass from my chamber.
Remember that you are only. 003 to.005 variance from Hornadys cases and a once fired case, . The measurements we use with the gauge is a datum point only, dont sweat it.

What actually does matter is the measurement that shoots best in your rifle whether its .050 jump or .020 jam.

##### Well-Known Member
I make and tap my own cases from once fired brass from my chamber.
Remember that you are only. 003 to.005 variance from Hornadys cases and a once fired case, . The measurements we use with the gauge is a datum point only, dont sweat it.

What actually does matter is the measurement that shoots best in your rifle whether its .050 jump or .020 jam.

Most of my rifles have a lot of free bore and can't get the projectiles close to the rifling's anyway but this tool is better than measuring off of the bullet points or me'plat. Like he said, don't sweat it.

#### Walt-Cen

##### New Member
Most of my rifles have a lot of free bore and can't get the projectiles close to the rifling's anyway but this tool is better than measuring off of the bullet points or me'plat. Like he said, don't sweat it.

Thanks for the reply guy, I guess I just don't agree with what the guy in the video is saying, he's using two different casings to get two different measurements which just complicates the exercise when he should be measuring the chamber for OAL from bolt face to ogive, which is what the OAL tool is designed to do. he's confusing OAL with head space.

But then maybe I just don't get it. lightbulb

Walt