I'm in the process of reloading some once fired 300 Weatherby brass. In making a dummy round it was having trouble
seating the shell about half the time. In examining the case the shoulder is all scratched and rubbed just off the top
of the shoulder in the body side. Also the rim is chewed up some. I adjusted the die for seating against the shell
holder and then a quarter turn more. My understanding is the cartridge seats against the belt and not the shoulder.
Somehow I'm getting the feeling i've adjusted the die wrong, but cannot figure out how. I ran this shell through both
my Mark V 300's with the same result. Can anyone take me by the hand and tell me what they think might be wrong?

IF you are sizing the case too much, it can make the case body (at the shoulder) expand.
Their have been multiple discussions here regarding sizing belted mag brass. Each has a different method/idea.
I load (7) different belted mag cartridges. My procedure is to partial neck size. It has worked for me for years. The one problem I encountered(similar to yours) was w/ a 6.5 x 300 WBY in a custom barreled Ruger #1. I tried everything I could do and made some phone calls. Finally, I ordered a different brand of dies. Problem solved. Hope this helps.

Unless you are able to size the case to chamber again the shoulder your brass will be short lived. Most people have no gauges for this and you cannot easily see the variations in sized cases.
If you use a Hornady case headspace gauge you can easily measure the the difference down to about +or -.001. You can measure about 10 to 20 fired cases and pick the longest. Then set your die to that dim or -.001 shorter. That will give you trouble free chambering and long case life.

I normally start my die setting with once fired cases from a rifle with a longer chamber. I remove the expander and slowly size the cases down until they are about .002 too long. Then I slowly adjust .001 down further and try. Once I get it barely dragging with a bolt gun I might stop there or I will go .001 more shorter so it always chambers easily.
When adjusting a 7/8-14 die a .001 adjustment is only .040 or so rotation on the OD of the die.
What you will find if you have one of the Hornady tools is that your sizing will vary from case to case .002 to .004 thousandths.
The variations are caused by varying amounts of lube on the cases, speed of the sizing strokes, dwell at the top of the stroke, number of strokes if you make multiple sizing passes, the brand of brass etc. You will be able to see why you get a tight case now and then.

quote:

Originally posted by cessna:
I'm in the process of reloading some once fired 300 Weatherby brass. In making a dummy round it was having trouble
seating the shell about half the time. In examining the case the shoulder is all scratched and rubbed just off the top
of the shoulder in the body side. Also the rim is chewed up some. I adjusted the die for seating against the shell
holder and then a quarter turn more. My understanding is the cartridge seats against the belt and not the shoulder.
Somehow I'm getting the feeling i've adjusted the die wrong, but cannot figure out how. I ran this shell through both
my Mark V 300's with the same result. Can anyone take me by the hand and tell me what they think might be wrong?

I agree. I treat belted cases the same as regular ones : partial sizing ! It means I ignore the belt (their dimensions vary from case to case anyway) and take headspace on the shoulder. Results : less case elongation (and cold working of brass) and greatly increased case life. I would even dare to say that it notably improves precision too ; this is valid for both (un-)belted cases.

Can you please do me a favour, take a fired case and see if it chambers easily.
If it does but has a slight feel on closing the bolt, you might have a short chamber.
An easy test is to run a feeler guage under the case when sizing it, start with .003" and size a case, clean, chamber it, if the same, try .005", repeat until a case chambers with a very slight feel. Do not go more than .015".
Once you have determined what amount required to size a case, have somebody turn that amount off the TOP of a shell holder and keep this shell holder with that die set.
It is quite common with Weatherby's that the shoulder doesn't get bumped enough, it's due the shoulder shape.

Hope this helps.

quote:

An easy test is to run a feeler guage under the case when sizing it, start with .003" and size a case, clean, chamber it, if the same, try .005", repeat until a case chambers with a very slight feel. Do not go more than .015".

Sounds like that would work, until, consideration is given to the belt on the case. Raising the case off the deck of the shell holder increases the presses ability to overcome resistance and increase the dies ability to shorten cases for short chambers.

Not easy to keep up with is the cases ability to resist sizing. If a reloaer chooses to increase the length of the case from the shoulder to the head of the case the best option is to adjust the die off the shell holder, I choose to use the feeler gage for consistency and verifying, others choose to make wild guestimates then go back and forth between sizing and the case length gage,

I have never found it necessary to grind the bottom of the die or top of the shell holder. I size/form cases that are shorter than a minimum length sized case .017" to a length of infinity or a paractcle .016" longer then a full length sized case, that would be .002" longer than a field reject length chamber for a 30/06.

Length of the case: from the shoulder to the head of the case or when using the datum of .375" the measurement is taken from the datum to the head of the case.

F. Guffey