Having troubles setting headspace on Weatherby brass - Need advise!

G

gpjohnson

New member
I am attempting to reload for my Weatherby magnums, 257, 7mm and 300. I have a MEC Marksman Press and RCBS dies. I have not tried the 300 yet, but the 257 and 7mm are coming out of the press with an increase, or length of headspace. Once fired Weatherby factory ammo, fired in my gun, is showing a headspacing of 2.0975. After running it through the RCBS F/L, the headspace measurement is 2.100. I attempted to chamber the resized piece and it would not chamber. I had almost the exact same result with the 7mm. When I contacted RCBS, they said they did not have a recommendation because their dies are designed to work on a press with cam-over. I called RCBS, MEC and Weatherby and no one can give me advice.
 
If you can't turn the die body down any further because it's hitting hard on the shell holder, you might try sanding a few thousandths off the top of the shell holder. If in fact the mec takes shell holders, I'm not too familiar with them.
 
If the FL die isn't screwed down far enough that the shoulder of your brass isn't touching the shoulder area of the die what you're experiencing is common. As a case goes up in to a sizing die it squeezes down on the sides/body of the brass and as this happens it's common for the case head to shoulder length to actually increase, if the dies isn't screwed down far enough for the shoulder on the case to come in contact with the shoulder area of the sizing die so my initial thought is your die isn't screwed down far enough. I can't recall ever having a FL sizing die that didn't need to be screwed down to at least touching the shell holder and generally slightly past touching where you get the "cam over" on the press taking all the slack out of the linkage. I would try screwing your sizing die down further, first.

Belted cases can present a different set of circumstances because of the belt but since you had the same problem with two different cartridges I'd bet your die needs to be screwed down further.
 
There can be, and often is a lot of variation in shell holders. Even from the same manufacturer. If you have another shell holder, you could try that.

There is a lot of slack left in the shell holder usually. Some people mistake flexing the press for taking up shell holder slack.

Changing your technique as far as case neck lube may help also. A hard pull coming out will pull on the shoulder.

Are they coming out/over the expander ball smoothish?

I am sure you know all this stuff. Just a friendly reminder.
 
I had the exact same problem before with 240 weatherby, looks like a common thing among weatherby, i ended up grinding a few thousands off the shell holder until I got the correct amount of cam over and also made sure the cases were properly lubed so when the expander pulled back out of the case it didn’t stretch the brass back out.
 
Or run your sizing die stripped and use a mandrel to set bullet seating neck size. Most shell holders you can slip shim stock under the brass and take up the slack, 0.002+ depending on how much you want to move the shoulder.
 
Thanks everyone for the help and I have tried all of the suggestions without luck, accept sanding the shell holder. What grit sandpaper would you guys suggest?
 
I use 80 grit emery cloth on a flat plate. I have a piece of flat stainless steel a foot square but any flat, hard surface will work granite countertop and use a full sheet of emery cloth as it is easier to hold in place while you sand. I work it in a circular motion and keep the pressure even or to the back of the shell holder and mic it often trying to keep it the same thickness as you go. After you have it where you want it colour the whole thing with a permanent marker, that way it won't get mixed up with the rest of your holders. Go slow measure often.
 
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Or, if you have a drill press you can speed up the process a bit. Grind the head of a 1/4"x1" bolt down a bit to clear the face of shell holder, clamp a piece of flat stock in vise, or use flat plate on drill press table and sand away.

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Regards,
hm

 
I was having the same issue with a different caliber. Before you do anything, watch this video. It helped me a LOT. I also added a Hornady headspace comparator gauge to my reloading bench. WINNING!


 
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13 thou(0.013) is ALOT of stretching, case head separation can occur with repeated movement of less. Don't mix brands of die/shell holder. Does fired brass extract/rechamber without sizing? If it does your die should be set 0.000 shoulder movement. Die should be set using the rifles chamber with a stripped bolt. A spent primer can be partially seated in a fired/unsized or a sized case and the actual space between bolt face and brass measured. Much more accurate than a comparator and a bolt with spring and striker in place.
 
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