OAL Measurement discrepancies - Slotted Case vs Cleaning Rod Method (.010")

[BoydAllen]

See what happens if you shorten it a couple of thousandths, and give it the steel wool treatment again and chamber it. That should give you some additional information as to where the bullet is. That you are precisely at touch is much less important that being able to get to a particular place, relative to the rifling, consistently. As your throat wears it gives you the ability to reproduce the same seating depth, starting with that point, and adjusting in or out to get to where the accuracy has been proven to be best. It is a pleasure to give someone a suggestion, that you know will work, and see that he has actually tried it, instead of discussing it to death and doing nothing.

 

[Nomad47]

You mentioned Savage. I wonder if the floating bolt head might be causing the .010 difference.

 

[savagedasher]

The picture of the bullet shows 2 real good land marks. I would my self call that a hard jam. They look over.010 in length. Larry

 

[smoooth]

I was thinking that as well. I have a feeling that the rod method worked properly, hence the .0015 overall difference vs. the .010 difference of the slotted case.

Either way, the lands have been found.

Good luck with the loads.

 

[Bindi2]

Buy the Hornady gear with the right case, make sure there is no carbon in the throat and go to it. After doing it once you will wonder why you mucked around with any other method. Took me 40years to learn.

 

[Nomad47]

Buy the Hornady gear with the right case, make sure there is no carbon in the throat and go to it. After doing it once you will wonder why you mucked around with any other method. Took me 40years to learn.

+1 Or better yet, make your own modified case with one of YOUR fired cases.

 

[BoydAllen]

One little tip on this:
The extra clearance that an unfired case has can be a good thing (for use with the Hornady tool), in that there is no chance that tightness of the case body in the chamber will interfere with the measurement. I have a 6PPC case that I got from Stoney Point (the original manufacturer of this tool) and the first thing that I did was to measure its "headspace" and compare it with a fired case from my rifle. The unfired case is .006 shorter in this dimension, so all I do is add that to the measurement that I get using the unfired case. This is also good in that it can be done for multiple rifles in the same caliber. One case will serve them all...accurately, as long as there is a fired case from each to measure.

 

[savageshooter86]

I seat a bullet long and close the bolt. Then check the bullet for rifling marks. Polish the bullet as Boyd said then seat the bullet deeper. I keep doing this until the rifling marks go away. Then I seat the bullet out further(closer to the lands) in very small increments until I just start to see the rifling marks. I call this touch.

I checked this measurement I got using the above method VS. my Hornady tool with modified case and got the exact same reading. So I call this touch

 

[mikecr]

IMO the cleaning rod method is the most accurate of any. No test case shoulder difference, or jamming of bullets issues.
We just don't know what's going on with his bolt/face.

An R-P Tool has a wide flat brass jag to seat against the boltface.

 

[gotcha]

Anyway, ......Your pic is excellent example of how nicely the scuffed bullet method works. The size and shape of the shiny mark you get is also a function of ogive shape and Leade angle. As stated earlier a bullet seated a few thou. shorter would probably also show a uniform shiny spot, just a little smaller. If you're REALLY anal you've just got to try it

 

[loudandproud]

Bumped it in a bit more. Marks disappear at around 2.784.
Im gonna say 2.875" is the number and call it good. Ill use the ogive mrasurement of this testbullet from here out to set up. Ill also keep an eye on the throat wear.

Thanks for the help to all who PMed me and offered advice here.

 

[gotcha]

Way to go! .......... You'll have that .308 cranking out 600 HP in no time. 8)