Originally Posted by BrentM
Pardon me again guys. Trying to understand this thread and Learn. I measures a 6.4x284 case using a OAL comparator Guage for a .30 cal. The new lapau brass measures 1.884 and my 6th fired case measured 1.914. Difference is .03.
How do you know how far to push the fired case or this case junk?
I and most folks think "OAL" in reloading and ammo stuff means the Over All Length of the cartridge; includes both the case and loaded bullet; it's the case head to bullet tip. Case length is the dimension from the case head to the case mouth. I think what your comparator gauge measures is the distance from the case head to a reference point on the case shoulder, and that's a good thing to measure when setting a die in a press to full length size cases. This dimension's often called case headspace.
That .030" difference in case headspace your gauge is measuring is quite a bit excessive, in my opinion, even on a case fired 6 times. If there's that much spread between new cases and fired ones in your chamber, I think either the new brass is a bit short in headspace or the rifle barrel chamber is way too long. I would expect no more than about .005" or so difference. Which leads me to think your gauge is not repeatable in its contact with the cases for both new and fired ones.
I think the 6.5x.284 had the same headspace specs as the .284 Win. Case specs are 1.814" -.007", chamber headspace is 1.810" + .010". The most spread from a minimum case in a maximum chamber would be .013". That a lot less than the .030" you mention. My concern is where you're measuring on the case. I think the gauge contact point's at the neck-shoulder junction on the case and that dimension on new cases is about right. Your fired cases shouldn't be more than about 1.890". That 30 caliber comparator gauge may not be best for the 6.5x.284 case as it may not be contacting the same diameter point on both new and fired cases. I suggest you get a nylon bushing at a hardware store with a 3/8ths inch inside diameter and 1/2 inch long. Use it to measure your cases headspace with the caliper as it's contact point will be about halfway up the shoulder at a .375" diameter reference. The numbers will be different but its the difference between them that's important.
Normal setback of fired case shoulders is about .002" to .003" for general use. Some competitors prefer no more than .0005" to a max of .0010".