Quote Originally Posted by Black Jaque Janaviac
BigEd,

I tried that technique of putting a spent primer in the pocket and closing the bolt. The result looked more like a fully seated primer. It did not visibly protrude beyond the case head so i did not bother to take measurements and instead moved to the masking tape trick.

I didn't figure it was necessary to know the exact thickness of each masking tape layer. I merely kept adding layers until the bolt refused to close, then measured the overall length of the empty case just the same as the primer seating trick you described.

Any reason why the primer seating method would be more or less reliable than the masking tape method?
"YES" the primer method is more reliable!

You can't compress a metal primer but you CAN compress the "stickem" on the tape that is "half" the thickness of the tape.

Tape is a "VERY" unreliable method for checking and setting headspace.

Example: What is your headspace on a "hot" day vs a cold day and where is your headspace if you use Chinese scotch tape. I'm saying this because I'm retired from a military overhaul depot and I spent the last 25 years in Quality Control as an Inspector. So I can tell you with 100% certainty that tape is "NOT" calibrated and it is "NOT" a precision measuring device.

If the primer was only protruding a small amount then you probably don't have a headspace problem you have a "resizing" problem from over resizing your cases and not fireforming them properly.

Minimum headspace for the 35 Whelen is 1.9835 and maximum is 1.9935, if your primer wasn't protruding ten thousandths (.010) from the rear of the case then you do not have a headspace problem. The cheap SOB used spent primer method of checking headspace is far more accurate than anything else.

A NO-GO headspace gauge for the 35 Whelen is $27.99 at Midway and is "FAR" more accurate than scotch tape.

http://www.midwayusa.com/viewproduct...tnumber=543326