Jamming into lands

1. OkiecatWell-Known Member

Messages:
50
Joined:
May 3, 2005
Dumb question. How do you determine that you are .005 or .010 jammed into the lands with the bullet. I have a stoney pt oal and a sinclair nut and calipers. I can't figure how once you touch the rifling how do you get a measurement of the jam. Thanks

2. EagletWell-Known Member

Messages:
2,779
Joined:
Feb 2, 2005
Okiecat,
There is no such a thing as a dumb question.
Hopefully I'm understanding the question correctly. Once you
touch the rifling, and you measure this many times to make
sure you're getting the same dimension, you write it down on
paper; let's say you measured 3.662" to just touching the rifling. Now if you want to be 0.010" into the rifling we
add 3.662" + 0.010" = 3.672" this new number is what you
want to have when you sit the bullet into the casing. you
is 3.672".
I hope I answered the question.

3. Ballistic64Well-Known Member

Messages:
669
Joined:
Dec 21, 2004
You can do the procedure eaglet describes,but depending on your neck tension/quality of brass,you may never actually get .010 into the lands.Just remember if this is a hunting gun and you seat this way,you may not be able to extract a live round without the bullet sticking in the throat and dumping powder all over.

4. ChawlstonGuest

[ QUOTE ]
Okiecat,
There is no such a thing as a dumb question.
Hopefully I'm understanding the question correctly. Once you
touch the rifling, and you measure this many times to make
sure you're getting the same dimension, you write it down on
paper; let's say you measured 3.662" to just touching the rifling. Now if you want to be 0.010" into the rifling we
add 3.662" + 0.010" = 3.672" this new number is what you
want to have when you sit the bullet into the casing. you
is 3.672".
I hope I answered the question.

[/ QUOTE ]

OAL can differ depending on the types of bullets you use with a constant seating depth. For instance if you are using a polycarbonate tipped bullet, the tips vary in dimension from lot to lot. Even non-poly tipped bullets vary in the distance from the bullet ogive to the bullet tip and that will give you erroneous depths for the same readings of OAL. To truly get an accurate loading specific distances off or into the lands, you will have to get an ogive tool for measuring seating depth. Sinclair has two models of them. Once you start using them, you will see which company really makes the most constistant bullets.

James

5. OkiecatWell-Known Member

Messages:
50
Joined:
May 3, 2005
Wow, thanks for the tutorial. That was so simple. I got it. I am using the Sinclair Nut and understand that part of the ogive dimension. Now back to the bench.