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I have a Hornady headspace gauge and I find it measures my .308 cases .009" shorter than actual headspace, as measured from the datum line on the sholder to the head of the case.
So if my Hornady headspace guage measures a specific .308 case at 1.624" that case is actually 1.633".
Anybody else notice this?
I know the Hornady guage is intended to be use as a reference, but how hard would it be to machine these guages to the correct specs.
I noticed the same thing, and it applies to all the individual adapters IIRC. It may well have some to do with the chamfers on the adapters. That said I use them only for reference against a "master" case I keep for each rifle so the real measurement number never presents a problem for me.
Quote:
Originally Posted by sliderspal
For the sake of argument we'll assume the chamber length is correct, 1.630"(minimum chamber), less than 1.634".(maximum cartridge)
For the 308 Win ( and family) the datum point is where shoulder measures exactly" .400" in diameter. Many times if you measure the bushings you may find them bore over,under and or have a taper on the leading edge of the bore.
If they're bored over size or the leading edge tapered the reading will short, bored undersize it will be longer.
If you want "real" numbers (Headspace - Head clearance) the bushing must be bored exactly to a specific diameter. For example...
http://i42.tinypic.com/116umvm.jpg
I make new bushings using steel or brass and bore them to the exact diameter. In the above, a .400" for the 308 family and a .375" for the '06. Those on the right I'm checking the "GO" gauges, case head clearance on the right.
Bill
How much are you selling steel ones for Bill?
Quote:
Originally Posted by Smokey262
Sorry Smoke....I'M RETIRED!!!!! :p
I was under the impression that the headspace guage was more of a reference than anything. Your headspace on a fireformed case vs. after resizing
With a GO gage you can set a zero reference point for measuring new and fired cases with cartridge case headspace gage.
Zero your gage with the GO gage and measure a fired case or a new case and add or subtract to get your actual cartridge headspace readings.
http://i122.photobucket.com/albums/o...Picture009.jpg
http://i122.photobucket.com/albums/o...1/SAAMI308.jpg
http://i122.photobucket.com/albums/o...m14chamber.jpg
Quote:
Originally Posted by bigedp51
So looking at the 7.62 Nato cartridge diagram above does it show that the min. cartridge headspace dimension is 1.628" and the max. cartridge headspace dimension is 1.634"?
The diagram shows 1.634-.006".
:pop2:
Nice smartass!Quote:
Originally Posted by Apache
Quote:
Originally Posted by sliderspal
LOL!!!
This is the classic "difference between the 308 and the 7.62 Nato" argument that starts on occasion.
I'm getting ready for the show! ;)
Although I won't allow it to get too stupid!
I use the Hornady tool only as a reference. Measure fired case, set back .002.
Just got the RCBS tool for both .223 and .308. Easier to use in my mind but they also could have set them up for SAAMI headspace and didn't. So they are also just used as a setback reference.