Determining where the lands are

S

shimmer

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I am just looking for information on determining "where the lands are"?
From what I understand, you seat a bullet in an empty case and chamber it. Then you look to see if there are some sort of marks on your bullet. Is this more or less correct? And what should you look for? Will it be 6 little indentations on the bullet (if it's a 6 groove barrel)?
 
That's the basic idea.

It is a pretty fiddly and fussing process though.

Sometimes marking the bullet with a black magic marker can make it easier to see the marks.

Also, by the time you actually see marks on the bullet, you are already into the lands a fair bit (perhaps as much as 25 thou).

Another way to do it: get a "Stoney Point" tool, which has a special cartridge case, and it allows you to push the bullet against the land via a rod, using only finger pressure.

Another way: F/L size a case, then very carefully slit the neck (e.g. with a Dremel moto-tool). Then adjust the neck tension so that it hold a bullet very lightly. Set a bullet in the case, very long, and then gently chamber it in your rifle. Carefully extract, and measure the length that the bullet has been pushed back to.
 
I have had good luck using a fired case, start the bullet into the case and chamber it. The bolt will lightly push the case onto the bullet that is against the lands as you close the bolt. Then gently eject the case and measure. Sometimes if the fired case tension is too little, the bullet will stick in the barrel and not come out with the case. I just pinch the case a bit if that happens.
 
Take an empty case, Dremel 3 short slots in the neck, insert the bullet just enough to keep it in place, insert it and close the bolt. Open the bolt, remove the round, and it'll show where it ran up against the lands before being pushed deeper into the case.
Adjust from there.
 
If you seat a flat base bullet upside down ( base forward) in a cartridge case, and chamber the round with gentle steady pressure on the bolt handle, when it comes out it will mirror the chamber length to the rifling. This dummy cartridge can then be kept for future reference.
 
Just a hint to add to the above ideas.....mark sides of the bullets with a felt pen as well.......so you can see if it "slips" out of the brass any when you remove the cartridge from the chamber....
 
Instead of a felt pen, polish the bullet with fine steel wool....the marks will show up plain as day plus if you need to adjust the depth, you just re polish the bullet and chamber it again to check for marks.
 
CyaN1de said:
Instead of a felt pen, polish the bullet with fine steel wool....the marks will show up plain as day plus if you need to adjust the depth, you just re polish the bullet and chamber it again to check for marks.
Click to expand...

I was instructed that this is the best way to do it, shine the bullet up with some steel wool. Keep turning the seating stem of your die " in" in 1/8th turns, which loosly equates to .005 of an inch, till you no longer see the marks on the bullet. Then move it back another .005, and start from there with your test loads, moving the seater stem in or down one 1/8 of a turn.
I do my measuring with a Sinclair comparator. FS
 
rnbra-shooter said:
That's the basic idea.

It is a pretty fiddly and fussing process though.

Sometimes marking the bullet with a black magic marker can make it easier to see the marks.

Also, by the time you actually see marks on the bullet, you are already into the lands a fair bit (perhaps as much as 25 thou).

Another way to do it: get a "Stoney Point" tool, which has a special cartridge case, and it allows you to push the bullet against the land via a rod, using only finger pressure.

Another way: F/L size a case, then very carefully slit the neck (e.g. with a Dremel moto-tool). Then adjust the neck tension so that it hold a bullet very lightly. Set a bullet in the case, very long, and then gently chamber it in your rifle. Carefully extract, and measure the length that the bullet has been pushed back to.
Click to expand...


Stoney point tool is now Hornady
 
Here's an easy way to do it.

Drop a bullet into the breech of the rifle, with the rifle facing down, until the bullet lands against the rifling. Tap it a bit with a cleaning rod so that it doesn't fall out.

Put the cleaning rod into the muzzle of the rifle until it contacts the bullet tip. Mark the cleaning rod at the muzzle with a piece of tape. Tap the bullet out and remove it from the action. Close the bolt of the rifle. Push the cleaning rod in farther until it touches the bolt face. Mark the cleaning rod with tape at the muzzle. Remove the cleaning rod. Measure the distance between the two pieces of tape, and that is your OAL to the lands of the rifling for that particular bullet.

I have found that this method requires far less screwing around than using the "bullet in the empty brass" technique.
 
I have the Stoney Point system, plus the drill and tap to make my own cases for different chamberings. It works very well indeed, and saves me a lot of fiddling. Regards, Eagleye.
 
You can make a seating depth gauge for a bolt action by taking a fired case. remove the primer drill and tap the primer hole 1/4-20 .then take a length of 1/4-20 threaded rod and turn it into the case.seat the bullet to be used short.insert the case into the chamber holding it there firmly slowly turn the rod in until you feel resistance.the ogive has now touched the lands.remove and measure the over all length.deduct 20,25 ,or 30 thou or your desired distance from the lands.
 
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