Hornady o.a.l.gauge
- Thread starter josebd
- Start date
Gargoyle
Finder Outer
Reference post #9
dellet
Gold $$ Contributor
Pretty sure it's 5/16 X 36tpi.
How is your selection of other calibers?
You can open up the neck on the modified case and run it through your sizing die
You can use any of the other methods mentioned in some of the other posts.
You can seat a bullet about .010" longer than what you got from the existing gauge and seat the bullet .002" deeper until you can insert it in the chamber with your finger and have it quit sticking when you hold the barrel up.
Coyotefurharvester
Silver $$ Contributor
If your modified case is -0.006 you need to ADD that to find bolt face to lands measurement. Because you are measuring from a point in front of where the bolt face actually stops. This is if you chamber the modified case and with bolt closed the case moves in the chamber, if it doesn't the case has a fit issue other than the shoulder contact.
The Hornady OAL gauge is threaded 5/16" 36 threads per inch and a "fine" 5/16" bolt is 24 TPI so yes, it won't fit. Stoney Point, the original company that make the OAL gauge just wanted to make it a little more difficult for folks to make their own modified cases. You can buy a 5/16-36 tap from McMaster Carr, etc.
Once you have a properly tapped and sized fired case you'll wind up with a length with questionable value. The Hornady tool, properly used, stops case movement forward when the shoulder hits the chamber. It does not measure length from the bolt face to chamber shoulder which is what you want. The tool does provide a reference point to follow throat wear so it's worth having for that.
Easiest way to measure is to strip bolt, seat bullet LONG in an unfired case with moderate neck tension. Polish bullet with 0000 steel wool. Measure case head to ogive with Hornady tool. Chamber round, see long rifling marks. Measure and polish again. Chamber again, etc. Seat bullet slightly deeper. Repeat until there are no marks on the bullet except from the ejector if you didn't strip that. Then do it all over again just to be sure.
The reason an unfired case works better is there will be no interference between the case and chamber walls which makes it difficult to get repeatable measurements. The length you're really looking for is from the bolt face to the start of the rifling.
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I'm a bit confused here.
If the OAL gauge piece of brass and the fired brass are both shorter than the chamber, then it seems the base to ogive length using the Hornady tool will both find the same exact spot on the lands. No reason to add or subtract anything.
If the OAL gauge piece of brass and the fired brass are both shorter than the chamber, then it seems the base to ogive length using the Hornady tool will both find the same exact spot on the lands. No reason to add or subtract anything.
If your Hornady tool piece of brass is longer than your fired brass...couldn't you run it through your sizing die without the bushing (keeping the neck big) to get it the same size as fired and bumped brass?
Dusty Stevens
Shiner
I guess itll take til page 2 for someone to mention how much of a waste that hornady tool is. Id rather my case be chamber full and actually touch the bolt face to get an actual ogive measurement. It takes minutes and as joe namath would say “its free!”
dellet
Gold $$ Contributor
The only useful measurement that you can hope to get from the Hornady tool is jump/jam. The two points of contact of shoulder and lands.
If you measure from base, to cartridge shoulder and subtract that from base to bullet ogive, you will have a meaningful number that you can apply to a cartridge with a different base to shoulder length.
The overall cartridge length will vary based on how the case is sized in relation to the chamber it is fired in.
If you lengthen the distance from base to shoulder, the overall length with increase, but the shoulder to ogive will still remain the same.
The problem is that setting the shoulder back, the overall length will stay the same, because the cartridge will now headspace off the bullet, instead of the case shoulder.
You would need to seat the bullet ogive the same distance from the shoulder to keep the bullet at a touch, and then the overall length or base to ogive would change, shorten.
That's why using a case sized as it will be loaded and chambered, is about the only way to get a useful number from the Hornady tool. Without some math.
If you measure from base, to cartridge shoulder and subtract that from base to bullet ogive, you will have a meaningful number that you can apply to a cartridge with a different base to shoulder length.
The overall cartridge length will vary based on how the case is sized in relation to the chamber it is fired in.
If you lengthen the distance from base to shoulder, the overall length with increase, but the shoulder to ogive will still remain the same.
The problem is that setting the shoulder back, the overall length will stay the same, because the cartridge will now headspace off the bullet, instead of the case shoulder.
You would need to seat the bullet ogive the same distance from the shoulder to keep the bullet at a touch, and then the overall length or base to ogive would change, shorten.
That's why using a case sized as it will be loaded and chambered, is about the only way to get a useful number from the Hornady tool. Without some math.
That's why 5/16 FINE is not definitive enough. It is a 5/16 x 36 is the correct and full nomenclature. It's the 36 TPI makes it slightly odd but available
Old Navy
Gold $$ Contributor
That might be true if you are a world class shooter and dealing with a case BTO of + or - .001". For the vast majority on this site it is a down and dirty handy to use tool to get started with.
Dusty Stevens
Shiner
Its a lot handier to use a free case instead of a contraption that relies on feel and costs money to use
Old Navy
Gold $$ Contributor
I started off using the free case. Still like the Hornady better especially when I screw on a new barrel. It a half hour I have an approximate measurement of the BTO on all the bullets I want to try. After I find the proper depth I use it get the same BTO when I reload that bullet again. It does rely on feel just like gently touching a 2 oz. trigger. Takes practice.
Ned Ludd
Silver $$ Contributor
Actually, it will take until page 2 for someone to mention the Hornady OAL gauge works just fine as it is. Leave the tool alone. Do not add or subtract some length difference between the Hornady case and a fired case to the measurements. The measurements are solely for establishing basic reference points and do not need to be "adjusted". I really do not understand why the use of the Hornady OAL gauge seems so difficult for some. Use the tool, take the measurements, find what loaded round dimensions actually shoot well on the target, then reproduce the measurements of those actual loaded rounds that shot well. Simple. Unless you make it difficult.
Cost money to buy. How so in use?
Dusty Stevens
Shiner
Have to keep buying or sacrificing cases
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