Will Learn
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- May 7, 2006
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What are some methods for measuring chamber length? I'm playing around with OALS for my reloads and am trying to figure out how far from the lands i should seat the bullet.
Measuring chamber length
- Thread starter Will Learn
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This tool and a modified case sold by Midway also in your cartridge does a good job of finding the lands.
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=570611&t=11082005
http://www.midwayusa.com/eproductpage.exe/showproduct?saleitemid=570611&t=11082005
You might try this in the handloading forum. Cerrosafe chamber casting alloy is one way to measure the chamber. However, if you are looking for bullet seating measurements the chamber casting is not what you seek. I have tried every commonly known technique to measure the C.O.L. (cartridge overall length). THe best way to date IMO is this; take a sized case and cut a small slit in one side of the neck with a dremel or similar. Be sure to cut the full length of the neck, no more no less. THis will leave the perfect amount of tension on the bullet you'll use next. Now just barely push a bullet in the neck. You should have adequate resistance. Now chamber the cartridge and close the bolt. Extract it CAREFULLY and measure the overall length. Do this 10 times. Your measurements should not vary by more the .002". If it does vary by more than that you've done something wrong.
The measurement you have from your 10 measurements is the distance you seek to determine seating depth. You will now simply subtract whatever amount of jump to the lands you want. I usually use .020" for a starting point. So you have your 10 measurements average, minus .020". THis is your COL for that bullet, in that caliber, in that gun.
Just make sure your measurements are consistent as you chamber each round and extract carefully. If your measurements are all over the place, something is wrong and none of the numbers can be trusted. Too little or too much tension holding the bullet usually gives eratic measurements.
There is also the tool made by Hornady made for achieving this same end. I have used it and did not care for it. THe Hornady cases that are made for the tool were slightly oversized and instead of bottoming out on the shoulder, stopped short. THis is extremely dangerous because the measurements one would get in that scenario will be too long and could create excessive pressure
Hornady mailed me replacements for 2 calibers and they were both oversized as well. Customer service guy admitted they DO NOT size the cases before machining threads in them for the tool. IMO the tool is a good idea poorly implemented. THe other way I described is cheaper, quicker, safer, and more accurate IMO.
The measurement you have from your 10 measurements is the distance you seek to determine seating depth. You will now simply subtract whatever amount of jump to the lands you want. I usually use .020" for a starting point. So you have your 10 measurements average, minus .020". THis is your COL for that bullet, in that caliber, in that gun.
Just make sure your measurements are consistent as you chamber each round and extract carefully. If your measurements are all over the place, something is wrong and none of the numbers can be trusted. Too little or too much tension holding the bullet usually gives eratic measurements.
There is also the tool made by Hornady made for achieving this same end. I have used it and did not care for it. THe Hornady cases that are made for the tool were slightly oversized and instead of bottoming out on the shoulder, stopped short. THis is extremely dangerous because the measurements one would get in that scenario will be too long and could create excessive pressure
Hornady mailed me replacements for 2 calibers and they were both oversized as well. Customer service guy admitted they DO NOT size the cases before machining threads in them for the tool. IMO the tool is a good idea poorly implemented. THe other way I described is cheaper, quicker, safer, and more accurate IMO.- Status
