Hornady OAL Gauge is Driving me Crazy(er)!

DrSteve

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I spent a couple hours today trying to get consistent CBTO readings on my Ruger Hawkeye 270 and some Nosler ABLR bullets. The readings are all over the place. I've had more consistent results with some other bullets. I try to be consistent, firm but not too firm, give it a couple taps. I got a few clumps of measurements, but the SD on 30 measurements was .02, if I remember right, and the ES was 67 thousandths! I didn't try burning incense or chanting mantras, but what's the frigging secret for getting repeatable readings with this thing? It must work or people wouldn't have used it all these years. I'm ready to put it away and try Erik Cortina's "Jam Method".
 

doverpack12

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Nov 21, 2012
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Could be a rough start to the lands making it really sensitive. How many rounds on the barrel?
 

DrSteve

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That tool is crap.

Take a sacrificial case and use a dremel tool to make a slit down to the neck/shoulder junction. Finger seat a bullet and chamber the round a couple times. Done.

If you don't have a dremel, then size the case just enough to catch the very rim of the case mouth and proceed as above.
Thanks. I'm going to try it.
 

birdiemc

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I drilled out my own cases and didnt tap the cases, just hold it on there with the calipers when taking a measurement. I can usually get 3 or 4 measurements within a couple thou. Which for me is good enough, I'm looking for a reference point for seating depth test which I try to start .010 off, but if I'm +- .005 I'm still good as long as I can find a good node as I move out.
 

DrSteve

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I just tried the method Erik Cortina describes on his YouTube channel to find "the jam" (CBTJ). He lightly seats and then chambers it in the gun (without slitting the case). A quick flick on the ejector than pops it out. After a warm-up, I took three measurements with the comparator and they were all within a thousandth of each other. How the CBTJ compares with the CBTO is apparently neck-tension dependent, so they are hard to compare. He starts at 20 thousandths off of CBTJ and runs a powder load test by shooting test groups. Once he has the best powder load, he tests "CBT Jumps" of 23, 26, 29, etc., looking for nodes by firing test groups and observing the group sizes. It is probably overkill for my hunting loads, but it seems interesting to me, and I'm going to give it a try.
 

338 dude

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I spent a couple hours today trying to get consistent CBTO readings on my Ruger Hawkeye 270 and some Nosler ABLR bullets. The readings are all over the place. I've had more consistent results with some other bullets. I try to be consistent, firm but not too firm, give it a couple taps. I got a few clumps of measurements, but the SD on 30 measurements was .02, if I remember right, and the ES was 67 thousandths! I didn't try burning incense or chanting mantras, but what's the frigging secret for getting repeatable readings with this thing? It must work or people wouldn't have used it all these years. I'm ready to put it away and try Erik Cortina's "Jam Method".
I quit using mine years ago for the same reason I would take 10 measurements and come up with an average number and it would be close enough and work OK but I’ve since moved on and either use Alex wheelers stripped bolt method which two people can do and come up with the exact same number or seat a bullet long color it with a sharpie chamber it you’ll see Marks from the rifling seat the bullet .001 of an inch deeper color the bullet again with a black sharpie and repeat this process until you have no marks from the rifling + .001 is your touch measurement and it is completely repeatable as well
 

DrSteve

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I quit using mine years ago for the same reason I would take 10 measurements and come up with an average number and it would be close enough and work OK but I’ve since moved on and either use Alex wheelers stripped bolt method which two people can do and come up with the exact same number or seat a bullet long color it with a sharpie chamber it you’ll see Marks from the rifling seat the bullet .001 of an inch deeper color the bullet again with a black sharpie and repeat this process until you have no marks from the rifling + .001 is your touch measurement and it is completely repeatable as well
Thanks. I tried that a while back before I got the OAL gauge. On some bullets, the OAL works reasonably well, which kept me coming back for more aggravation.

I also plan to try Dog Rockets suggestion with the split case and see how the measurements compare with Erik's jam method.
 

wildbill 2020

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Nov 8, 2020
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grantsville,utah
I spent a couple hours today trying to get consistent CBTO readings on my Ruger Hawkeye 270 and some Nosler ABLR bullets. The readings are all over the place. I've had more consistent results with some other bullets. I try to be consistent, firm but not too firm, give it a couple taps. I got a few clumps of measurements, but the SD on 30 measurements was .02, if I remember right, and the ES was 67 thousandths! I didn't try burning incense or chanting mantras, but what's the frigging secret for getting repeatable readings with this thing? It must work or people wouldn't have used it all these years. I'm ready to put it away and try Erik Cortina's "Jam Method".
This is going to sound crazy but it works buy a wood dowel small enough to go down you barrel with the bolt closed push dowell to face of bolt mark it with a marker /pen mark at top of the barrel then what ever bullet your using push the bullet in the chamber take the wood dowel down the barrel till the dowel touch’s the bullet the hold your finger on the bulletise the dowel to push the bullet the push bullet back into lands mark the dowel again this will give you your oal remover to seat your bullet at least 0.20 lower from the tip or once you get your oal get bullet comparater and that will tell you where the ogive is and seat your bullet accourdingly
 

birdiemc

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This is going to sound crazy but it works buy a wood dowel small enough to go down you barrel with the bolt closed push dowell to face of bolt mark it with a marker /pen mark at top of the barrel then what ever bullet your using push the bullet in the chamber take the wood dowel down the barrel till the dowel touch’s the bullet the hold your finger on the bulletise the dowel to push the bullet the push bullet back into lands mark the dowel again this will give you your oal remover to seat your bullet at least 0.20 lower from the tip or once you get your oal get bullet comparater and that will tell you where the ogive is and seat your bullet accourdingly
That actually sounds much easier than jacking with the hornady tool
 

Dog Rocket

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Mar 17, 2018
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Washington State
This is going to sound crazy but it works buy a wood dowel small enough to go down you barrel with the bolt closed push dowell to face of bolt mark it with a marker /pen mark at top of the barrel then what ever bullet your using push the bullet in the chamber take the wood dowel down the barrel till the dowel touch’s the bullet the hold your finger on the bulletise the dowel to push the bullet the push bullet back into lands mark the dowel again this will give you your oal remover to seat your bullet at least 0.20 lower from the tip or once you get your oal get bullet comparater and that will tell you where the ogive is and seat your bullet accourdingly
That is a really old method, but it isn't very precise. This was one of the first methods I ever learned.

The bullets themselves aren't all exactly the same length (the reason we use CBTO), the method of marking the stick isn't precise either.

If you used a range rod that was precisely made with a recess cut in one end for the meplat so you are measuring off the ogive, and used a good dial caliper to measure the amount the range rod sticks out from the muzzle, then you might get close.
 

Dog Rocket

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569
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Thanks. I tried that a while back before I got the OAL gauge. On some bullets, the OAL works reasonably well, which kept me coming back for more aggravation.

I also plan to try Dog Rockets suggestion with the split case and see how the measurements compare with Erik's jam method.
Will there be a difference between true "touch" and the little bit of pressure ("jam") that it takes to do the split case method? Yes.

Will it matter? No. All we need is a place to start from. There is enough variability in the individual bullets and cases that there will always be a +/- set of tolerances anyway.

The split case method is as good as any to start from, just be sure to remove any burrs fron the inside of the neck after splitting before you do the seating/chambering.
 

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