Headspace gage - Am I on track?

[Aitch]

After some fits and starts, and with some help from Rustystud, janderson0 and rayjay, I turned a gage this weekend for my 6.5-284.
Shoulder is 70 degrees included angle with a .386 diameter thru hole. I made it so it would fit the Sinclair holder that I got with for a bullet comparator and long enough to gage a loaded round.
I had two rounds that would not chamber in my initial loading trials. Turns out the two rounds that would not chamber were .008 longer at the shoulder datum than the cases that chambered fine and fired.
The brass that I was loading came with the Speedy built rifle.
Given what I was told, I think it is all once fired.
That much variation surprised me, maybe these two came from the PO's other 6.5-284.
It's pretty clear I wasn't bumping the shoulder.

 

[Rustystud]

Nice Work! There is nothing like metal gauges to measure by.

Rustystud

 

[billmo]

Nice work Man. Bill

 

[BigJim]

Real nice!!!!

 

[BoydAllen]

Very sanitary work...Depending on how large the neck of your chamber is, you might want to make sure that the transition between neck and shoulder in you gage is beveled, or radiused larger than your chamber or die. A while back, I ran into a situation where I was trying to use a piece of barrel that has the front of my chamber as a gauge for setting the FL die for another .262 neck chamber that was not cut with my reamer. I caught it, but not till I had pushed the shoulder back too far on a couple of cases. The gage was stopping on the unsized portion of the neck, left by the bushing chamfer, rather than the shoulder. Evidently, the neck of his chamber was larger than mine. Again...really nice work

 

[rayjay]

It's a good feeling to know EXACTLY what's going on. Good looking tool.

 

[Cheechako]

Aitch

Don't forget to check the headspace twice - once after firing and again after you do all of your sizing operations. Body and/or neck sizing will often change headspace, sometimes enough that you cannot chamber a case that previously fit. This is especially true of the "Ackley" type cartridges. Body sizing those relatively straight cases means that the brass has to go somewhere and that usually means that it will squirt out the shoulder.

Ray

 

[Aitch]

Thanks all for the kind words. The through diameter is .386 which is, depending on whose diagram you use, datum diameter or within a couple of thou. The chamber neck is .297.
Generally, I'd rather make something than buy it, if it's within the capabilities of my equipment and ability.
I want to build a gage to measure the chamber datum next, but have not figured out exactly what it needs to look like.
Right now I can generate number but it is relative only to itself and other cases.