[oldhammy1]

I have reloaded 30-06 and .270, and just picked up a 300 win mag. I am confused about the case seating, and how that relates to reloading. Do factory rounds seat on the belt, and then once sized, they seat on the neck? Does this mean you would have to sight in for each scenario. Is factory unfired brass going to seat differently than sized brass? Anyway, if someone could provide a short, 300 win mag reloading for dummies summary for me, I would greatly appreciate it.

[rcmodel]

Factory loads headspace off the belt, in theory at least. There may possibly be some custom rifle manufactures chambering off the shoulder however.

Anyway, after firing in a bolt-action, you can adjust the sizing die to headspace off the shoulder and much get better case life.

As for different zero's, I doubt you can see the difference in an average hunting rifle.

And there would be no way to prove it if you could see it.
For instance, is the different POI due to the headspace method used, or due to differences between factory & hand-loaded ammo such as powder, primer, bullet, etc?

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

[Shoney]

I had a lenghty answer, but rcmodel posted about the same before I posted.

This may help. Once the case has been fireformed to the chamber, I full length resize just enough to touch the shoulder. The case (at least in theory) is then headspacing off the shoulder.

When I adopted the above method, I got longer case life. You should be checking the case stretch just above the belt after each firing. If not monitored for thickness, it can lead to case head separation.

[iiranger]

In his books, Mr. Ackley clearly states that the belt was necessary for the funnel shaped cases of .300 H&H or .375 H&H to headspace, --well duh?-- BUT once they started putting a shoulder on the case, it was headspaced by factories off the shoulder just like the "rimless" cases... Now a custom chamber... as you order, whatever you pay for...

If you gun is a bolt action and you are not "going in harms way" with dangerous targets, then, as said, if you neck size you will experience much better case life. If you choose to full length size, then you will work the brass more. Feed should be alot more reliable, important if something is after you, but this extra reduction/expansion work hardens and wears out the case. HAPPY HOLIDAYS. luck. Happy trails.

[rcmodel]

if you neck size you will experience much better case life. If you choose to full length size, then you will work the brass more.I think it's important to differentiate between "neck sizing" and sizing to headspace off the shoulder, as opposed to "full-length sizing".

To size to headspace, you adjust the die out until the bolt will barely close on an empty case.

That is more then neck sizing, but less then full-length sizing where you headspace off the belt.

Anyway, the case is fitted perfectly to your chamber, and will not stretch as much as if you full-length sized and used the belt to headspace instead of the shoulder.

http://i81.photobucket.com/albums/j219/rcmodel/KTOG/1224.gif
rcmodel

[oldhammy1]

I may be demonstrating my ignorance here, but if you only neck size, aren't there potential failure to feed issues? Doesn't the entire case stretch and expand, even slightly, between firings. I think I need to read up more on this somewhere. Can anyone point me to some websites or literature that I can read that will help me fully understand this process? I am the type of guy that likes to do his homework before jumping into something new, so I appreciate all your help and knowledge sharing.