Measuring Headspace for 338 Win Mag

[grry10]

I'm using the Brownells/Sinclair version of the headspace comparators, but they work the same as the Hornady.

 

[SJB358]

if you want to extend your brass life you can form a false shoulder before the first fire and eliminate a lot of the case stretch .

I suffered a few case head seps as a young loader and quickly learned the false shoulder method to extent my brass life. It’s paid off in keep my fingers, eyes, etc and brass life and it takes but a few extra minutes.

 

[SJB358]

I’ve used many deprimed 9mm, 10mm and 45 acp cases to set headspace before I had comparators. Knowing the numbers you get aren’t real, you’re just trying to size for the difference.

 

[RiverRider]

I bought the RCBS headpace gauge many years ago when I was just getting into centerfire rifle reloading. I learned pressty quick that it did not give me an absolute measurement, but it was good for relative meaurement.

These days I just use my old Stoney Point bullet comparator using an insert that fits somewhere near the middle of the shoulder. I know that's not "the" datum line...I don't think there's a tool out there that will put you precisely on "the" datum line, and a relative measurement is just fine. I only use the measurement to keep track of how much I am changing shoulder bump as I adjust my sizing die (I leave them set once I get them where I want them). I DO NOT just go by the measurement to determine where I want the shoulder, I go by feel---at least on a bolt rifle. For my ARs I try to keep shoulder bump at a minimum for case life, but for reliable function you have to be willing to go an extra couple of thousandths.

If you do the arithmetic, turning the locking ring on a sizing die the equivalent of a one-second tick of an analog clock (which is 6 degrees) changes shoulder bump by about 1.2 thousandths of an inch.

 

[stevelsd]

I bought the RCBS headpace gauge many years ago when I was just getting into centerfire rifle reloading. I learned pressty quick that it did not give me an absolute measurement, but it was good for relative meaurement.

These days I just use my old Stoney Point bullet comparator using an insert that fits somewhere near the middle of the shoulder. I know that's not "the" datum line...I don't think there's a tool out there that will put you precisely on "the" datum line, and a relative measurement is just fine. I only use the measurement to keep track of how much I am changing shoulder bump as I adjust my sizing die (I leave them set once I get them where I want them). I DO NOT just go by the measurement to determine where I want the shoulder, I go by feel---at least on a bolt rifle. For my ARs I try to keep shoulder bump at a minimum for case life, but for reliable function you have to be willing to go an extra couple of thousandths.

If you do the arithmetic, turning the locking ring on a sizing die the equivalent of a one-second tick of an analog clock (which is 6 degrees) changes shoulder bump by about 1.2 thousandths of an inch.

Good thoughts Scotty and RiverRider!
Super thanks!

Stevelsd

 

[PJGunner]

Let's keep this simple. Step one, forget about the belt. It's not easy to get a measurment and if you do they're usually out of specs anyway.

This is how I set up my sizing die for bottleneck cartridges. 1. Take a once fired factory round and blacken the neck and shoulders with a Magic Marker or Sharpee pen. Some people like to smoke the neck and shoulder, but I find the Magic Marker/Sharpee pen a bit better. 2. Carefully lubricate the case. 3. Loosen the lock ring on the sizing die and back off about two turns from when the die is set to touch the shell holder. 4. Size the case. Note where the marks are on the case and turn the die down about a half a turn and size again. Turn down some more, and resize again. What you are looking for is the marks on the blackening just touching the shoulder. 5. Clean the lube from the case and try it in the rifle. It may chamber just a bit on the snug side. If so, turn the die down ever so slightly, lube and size again. Wipe off the lube and try in the rifle. If it slides in as easily as a factory round, you should be good to go. If not, usually one more very slight adjustment should fix the problem. 6. Tighten the locking ring for the die and you're done. You have just set your sizing die up for a custom fit to your specific rifle, rather than a generic one size fits all guns. Paul B.

​

 

[stevelsd]

Let's keep this simple. Step one, forget about the belt. It's not easy to get a measurment and if you do they're usually out of specs anyway.

This is how I set up my sizing die for bottleneck cartridges. 1. Take a once fired factory round and blacken the neck and shoulders with a Magic Marker or Sharpee pen. Some people like to smoke the neck and shoulder, but I find the Magic Marker/Sharpee pen a bit better. 2. Carefully lubricate the case. 3. Loosen the lock ring on the sizing die and back off about two turns from when the die is set to touch the shell holder. 4. Size the case. Note where the marks are on the case and turn the die down about a half a turn and size again. Turn down some more, and resize again. What you are looking for is the marks on the blackening just touching the shoulder. 5. Clean the lube from the case and try it in the rifle. It may chamber just a bit on the snug side. If so, turn the die down ever so slightly, lube and size again. Wipe off the lube and try in the rifle. If it slides in as easily as a factory round, you should be good to go. If not, usually one more very slight adjustment should fix the problem. 6. Tighten the locking ring for the die and you're done. You have just set your sizing die up for a custom fit to your specific rifle, rather than a generic one size fits all guns. Paul B.

Nice, NIce, NIce Paul!!​

 

[stevelsd]

I suffered a few case head seps as a young loader and quickly learned the false shoulder method to extent my brass life. It’s paid off in keep my fingers, eyes, etc and brass life and it takes but a few extra minutes.

Not Sure what a false shoulder method is? Does this only apply before FF.

 

[RL338]

Not Sure what a false shoulder method is? Does this only apply before FF.

Before fireforming.

 

[stevelsd]

Before fireforming.

Oh Nice thank you!!!!