How to measure for bullet seating depth?
- Thread starter swift81
- Start date
This was a pretty good thread: http://www.canadiangunnutz.com/forum/showthread.php?t=218845
In the good old days, we would smoke the bullet and keep chambering it, and trying diff. lengths until we could see the marks left by the rifling/throat and adjust accordingly. These time tested methods as well as newer(read:expensive) methods are moot alot of times because the magazine size quite often determines your OAL.
If you're just looking to get the same measurement that the handloading manual suggests, go to your local gunshop or try one of the dealers on this site and buy a "nut gauge". Hopefully you have a vernier caliper already. The gauge has various holes corresponding to calibre and will seat on the ogive approximately where the lands will meet it. Then deduch the length of the nut gauge form the OAL. The seller of the gauge will be glad to show you how to do it.
If you're looking to seat 5 thousandths of an inch off the lands, seat a blackened bullet in an unprimed/charged/sized case and chamber it in the rifle you are loading for.
Push the bullet back in the case until the action is closed.
Put the cartridge into the shell head holder on your press.
Make sure the plunger on your seating die is backed out all the way and turn the die into the press.
Nest turn the plunger down until it just makes contact with the bullet tip, then turn the plunger down 1/2 turn.
This should give you an OAL tailored to the specific rifle.
Mark the dummy cartridge and save it, so you can change the setting on your die for other rifles of the same configuration.
Remember, every 500 rounds or so the plunger may have to be backed off a thou or two to make up for throat/land erosion.
Make sure your magazine will accomodate the length or you will have to either single load or seat the bullet deep enough to fit in the mag.
DO NOT SEAT THE BULLET TIGHT INTO THE LANDS. It could and probably will increase pressures. Unless you have a custom, purpose built, target rifle, whose tolerances have been reduced and seem to be able to handle the excess pressure. Even that is an uncomfortable situation.
bearhunter
If you're looking to seat 5 thousandths of an inch off the lands, seat a blackened bullet in an unprimed/charged/sized case and chamber it in the rifle you are loading for.
Push the bullet back in the case until the action is closed.
Put the cartridge into the shell head holder on your press.
Make sure the plunger on your seating die is backed out all the way and turn the die into the press.
Nest turn the plunger down until it just makes contact with the bullet tip, then turn the plunger down 1/2 turn.
This should give you an OAL tailored to the specific rifle.
Mark the dummy cartridge and save it, so you can change the setting on your die for other rifles of the same configuration.
Remember, every 500 rounds or so the plunger may have to be backed off a thou or two to make up for throat/land erosion.
Make sure your magazine will accomodate the length or you will have to either single load or seat the bullet deep enough to fit in the mag.
DO NOT SEAT THE BULLET TIGHT INTO THE LANDS. It could and probably will increase pressures. Unless you have a custom, purpose built, target rifle, whose tolerances have been reduced and seem to be able to handle the excess pressure. Even that is an uncomfortable situation.
bearhunter
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