How to measure chamber depth to seat bullets?

[MNbogboy]

I see there is another post on this subject that is hot today...

Additionally another plus to the modified case system is once you are "set" to the lands you can set your seating die precisely with the test "case/bullet combo" and then adjust it to from the lands to any position you desire (without a calculator, bullet comparator and a bunch of trial and error!)......

Need the numbers for another brand of bullet?...No problem...Push the bullet out with the eye bolt...Seat the new bullet partway...feed it in the rifle slowly...extract it slowly....DONE...one or two minutes...simple....

Randy

 

[Bart B]

Does anyone know how much they "chase the leade" maintaining a fairly consistant bullet jump to rifling for every hundred rounds they shoot for a given cartridge? In wearing out a .264 Win. Mag. barrel, it was about 30 thousandths. With 30 caliber magnums it's been about half that much.

 

[daniel brothers]

here's another easy way.......

[ame=http://www.youtube.com/watch?v=Jv-D1mEI514]Bullet Seating Depth Method - YouTube[/ame]

 

[tacsniper0888]

here's another easy way.......

Bullet Seating Depth Method - YouTube

This is the method I tried but can't get consistent results or get it to work. My shoulders are blown all the way forward. Any ideas?

 

[MNbogboy]

Does anyone know how much they "chase the leade" maintaining a fairly consistant bullet jump to rifling for every hundred rounds they shoot for a given cartridge? In wearing out a .264 Win. Mag. barrel, it was about 30 thousandths. With 30 caliber magnums it's been about half that much.

Good point...Bart B....That is another reason why my method works well for me...I can find the lands with a quick check and adjust accordingly.....I have found I can easily lose .010 in my .260s in about 500 hundred rounds or so...However I do not usually check until after accuracy drops off.....Mine are only hunting rifles, but if one is into predictive/preventative maintenance, a person might think about adjusting seating before accuracy drops off...

Randy

 

[tacsniper0888]

MNbogboy could you please explain your method in a little more detail? I would like to try it but I am lost. I don't understand. Thanks man.

 

[MNbogboy]

Tac,
Imagine Daniel Brother's method only you slowly completely close the bolt on your first try....Slowly extract the test case and measure....The key is neck tension...It has to be heavy enough to overcome the ejector/extractor but light enough so you can push it in by hand and not so heavy that you drive it into the lands (it will bite the lands some and you will have to allow for that)....

The drilled & tapped case heads and flat spots allow you to easily push the bullet back out (with the eye bolt & wrench) for subsequent measurements and or to change bullets....

I have also used the Daniel Brother's method and have found it to be quite accurate especially with a micrometer seating die....Maybe your inconsistency is related to your brass and the "feel" of just touching the lands is not as evident.....If your brass is not reasonably concentric the bullet will prematurely contact one side of the lead and push the bullet in farther than it would if it were truly concentric....

I will try & take some pictures of these simple gadjets and post them if you would like...

Remember that once you "find" the lands it is or will be just a baseline number and you will work accordingly from there....

Good luck,
Randy

 

[Bart B]

For what it's worth, note that one can get a more accurate length by not using the bolt at all.

Instead, seat a bullet slightly in a case neck with medium grip tension, then push the round into the chamber until it stops. That's where the case and bullet will be when the round fires. Use a rod down the barrel from the muzzle to push that round out without changing the bullet's location in the case neck. Pulling a round out with the extractor with a bullet so seated may let the case neck slip back a bit on the bullet. If the force is on the bullet, the case will stay in place on it. 'Course this assumes your case doesn't bind up anywhere in the chamber.

Do this with 5 cases but carefully measure the case head to the rifling contact point on the bullet and you'll see a spread of a few thousandths across all of them. That's the spread across your case headspace; exactly what happens for your ammo when the bolt's closed and round fired; the headspacing point on the case is hard against the same place in the chamber. The case head may or may not be against the bolt face when this happens.

 

[Mike 338]

Its been said before. I like the Hornady OAL guage + a Hornady dummy round in that caliber which is usually sold right next to the guage. It's fast, easy, clean, accurate (enough for me anyway) and all fits in a small drawer. About 35 bucks and your in business.