Bullet seating question

[sactobill]

I am new to reloading and have been reading about rifle shooters seating their bullets within a certain distance from the lands. How do you go about measuring this?

For example, I want to create a load that is .10 from touching the lands, what are the steps involved to determine how to do this?

Thanks!

[troysland]

Found this pretty good link with details.

https://forums.cabelas.com/showthread.php?t=6652

[Horton Fenty]

Bolt action? I take a fired case and insert the bullet I'll be using just in the neck a little bit. Chamber the round gently and slowly, remove and measure your coal and cbto. Do it a few times for an average and use the exact same bullet each time. For better feel you can remove the firing pin assembly from the bolt. That's what I do anyway.

[blockfort]

Bolt action? I take a fired case and insert the bullet I'll be using just in the neck a little bit. Chamber the round gently and slowly, remove and measure your coal and cbto. Do it a few times for an average and use the exact same bullet each time. For better feel you can remove the firing pin assembly from the bolt. That's what I do anyway.

If you do it this way, make sure you use that same bullet when you test your seating die. A bullet of a different length set to the same overall length as your test round will have a different distance from the lands.

[joelogic]

Bolt gun only. Semi-Auto = mag length.

[Anti-Hero]

Get a Hornady COAL gauge.

[gunboat]

or a sinclair bullet seating depth gage --

[alfred1222]

I got a pair of calipers and measured it to exactly what my reloading manual says the COAL should be. If it was over or under, i pulled it and adjusted my seating and crimping die. guess and check, and making sure you have a high quality seating die, will allow you to seat the bullet at the same depth every single time

[J-cat]

I used to use the slit case method. But then I realized that the .010" off the lands myth is just that. Also, depending on the round you're shooting, the lands move forward with throat erosion so your .010" figure today won't be the same next year. I prefer to load normal looking rounds and play with the powder charge instead.

[Horton Fenty]

If you do it this way, make sure you use that same bullet when you test your seating die. A bullet of a different length set to the same overall length as your test round will have a different distance from the lands.

Yes, use the same bullet throughout setup.

[blockfort]

You missed the part where I said......and use the exact same bullet each time.

I thought you were talking about using the same bullet for multiple measurements of the chamber. But you didn't tell him to use that same bullet for setting the die.

[Bill Steele]

I used to use the slit case method. But then I realized that the .010" off the lands myth is just that. Also, depending on the round you're shooting, the lands move forward with throat erosion so your .010" figure today won't be the same next year. I prefer to load normal looking rounds and play with the powder charge instead.

I generally agree with this advice, although I have found seating depth to change the consistency of POI, I suspect a part of that was how that seating depth effected pressures which affect the barrel harmonics, which affect who much the bullets scatter on target. Likely an adjustment of powder charge may have performed the same adjustment.

Another factor in seating depth (or jump, as in jump to the lands) is the bullet you are loading, some appear to prefer some jump while others seem to perform better closer to the lands. Yet another factor is how precisely the chamber and bore are aligned. I have been told by a few guys that seem to know something about bench rest shooting that a gun whose chamber is less than perfectly aligned will shoot better with more jump, ones with perfect alignment better with no jump (at least with some brands of bullets).

It goes on and on, with some very strong (and widely varying) opinions on the subject. A good source of data on the subject is: http://www.accurateshooter.com/ Another good place is snipershide forums.

[Horton Fenty]

I've almost purchased one of those Hornady or Sinclair units a couple times. Instead I bought a comparator setup with bump gauge and bullet comparator bodies. It's really nice to be able to quickly and accurately measure shoulder set back and cartridge base to ogive.

I thought you were talking about using the same bullet for multiple measurements of the chamber. But you didn't tell him to use that same bullet for setting the die.

Yea sorry, I assumed by extension that was understood.

[sactobill]

Horton,

Can you tell me about the comparator setup and where you purchased it from?

Thank you.

[RandyD]

I am new to reloading and have been reading about rifle shooters seating their bullets within a certain distance from the lands. How do you go about measuring this?

For example, I want to create a load that is .10 from touching the lands, what are the steps involved to determine how to do this?

Thanks!

This is a complicated topic to write about because there are several methods to use to determine the distance from the bolt face to the land, and not everyone agrees which is the best method. I recommend going to 6mmbr.com and read the reloading forum. The shooters on that site are in pursuit of accuracy and most of them are benchrest shooters. They universally agree that the best accuracy from a rifle is realized by determining each rifle's preference pertaining to the exact measurement from the bullet's ogive to the lands. Some rifles like the bullet to be .002 off the lands and some like it .002 jammed into the lands. You have to experiment to find the exact measurement for your rifle.

Have fun reading, more fun trying and enjoy the results.