I don't have an oal gauge. I put my longest bullet into an empty/fired/unsized case and chambered it in my 6.5cm Savage. The rifling grabbed the bullet and held it as I unchambered the shell. I kept seating it deeper until it stayed with the shell as I unchambered it. Is this an acceptable way to judge a firearms oal?
Determining OAL without gauge?
- Thread starter CJS-6.5
- Start date
Close enough assuming you're planning to stay a safe distance from the lands. Keep in mind that measurement only applies to that bullet. Let's say that was a 175 smk. If you switched to a 178hpbt, you'll need to remeasure. The hornady tool and modified case is relatively inexpensive and worth the cost.
Here's the method I use:
Take a cleaning jag and cut/file the face of it flush; get rid of the little nipple so it's a large flat square surface area. Screw that onto your cleaning rod.
Cock the bolt (so the firing pin isn't sticking out of the bolt face), and close the bolt on an empty chamber.
Insert the cleaning rod until it bottoms out on the bolt face. Mark that location on the cleaning rod (sharpie, pencil, I often put a strip of tape exactly flush with the muzzle).
Now pull the rod out 4" or so, open the bolt, and insert a bullet followed by a new or resized case into the chamber. You should be able to lightly push the back of the case to get the bullet to find the rifling. Just for my own paranoia, I will then push the cleaning rod forward, unseat the bullet maybe 1/8" from the rifling, then push the case back forward until the bullet BARELY touches the rifling and stop pressing. IMO you don't want to have any crush fit here with the bullet into the rifling and it doesn't take much pressure to push several thou into the lands. Ensure the barrel is fairly level here so your cleaning rod won't slip out, then mark the rod at the muzzle in the same fashion you did earlier.
Measuring mark-to-mark will give you the COAL with THAT particular bullet to the lands. I typically subtract .015 to 0.025" as a starting point for load development.
Take a cleaning jag and cut/file the face of it flush; get rid of the little nipple so it's a large flat square surface area. Screw that onto your cleaning rod.
Cock the bolt (so the firing pin isn't sticking out of the bolt face), and close the bolt on an empty chamber.
Insert the cleaning rod until it bottoms out on the bolt face. Mark that location on the cleaning rod (sharpie, pencil, I often put a strip of tape exactly flush with the muzzle).
Now pull the rod out 4" or so, open the bolt, and insert a bullet followed by a new or resized case into the chamber. You should be able to lightly push the back of the case to get the bullet to find the rifling. Just for my own paranoia, I will then push the cleaning rod forward, unseat the bullet maybe 1/8" from the rifling, then push the case back forward until the bullet BARELY touches the rifling and stop pressing. IMO you don't want to have any crush fit here with the bullet into the rifling and it doesn't take much pressure to push several thou into the lands. Ensure the barrel is fairly level here so your cleaning rod won't slip out, then mark the rod at the muzzle in the same fashion you did earlier.
Measuring mark-to-mark will give you the COAL with THAT particular bullet to the lands. I typically subtract .015 to 0.025" as a starting point for load development.
Ive done this method and found it to the thousandth without calipers when I didnt have a 6mm comparator bushing at one point. Just used the micrometer setting as my reference.
If you dont have a micrometer topped die or comparator you can still just log the coal as you slowly lower the seating depth but note that it will have some range of variation built into the tips of the bullets so you might want to test a few to make sure that you didnt get an outlier on the first. But you can easily tell exactly what length you have to the lands by feel.
If you dont have a micrometer topped die or comparator you can still just log the coal as you slowly lower the seating depth but note that it will have some range of variation built into the tips of the bullets so you might want to test a few to make sure that you didnt get an outlier on the first. But you can easily tell exactly what length you have to the lands by feel.
Just picked up one of the Hornady OAL tools. Thing is sweet makes it quick and easy to get a starting point wish I would have gotten it a while ago.
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Sent from my XT1585 using Tapatalk
^^^^^This^^^^^
I'm sure the DIY methods can work, but having the right tool for the job for me is the best route to go.
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