Reloading the 300WBY mag??

[Varmint Hunter]

My buddy has been having difficulty reloading his for 300Wby. I'm not sure why because he has reloaded for it for years. He says that the FL sizing die is crushing cases and he can't figure out the problem So, he dropped off a few 300Wby die sets and some brass for me to look at.

I disassembled the dies and cleaned them up. I wanted to see where the shoulders were at on the fired cases before adjusting the dies for my press. A quick look at the info for my Hornady head & shoulders headspace gauge showed no mention of any Weatherby cases. Can my tool be used to measure the headspace on a Weatherby double-radius case?

If not, how do you set up a FL die so that it moves the shoulders back a few thousandths?

 

[Joe6pack]

Did he change shell holders ? Is it a new batch of brass with thicker neck walls, were the mouths chamfered ?
I've used the Hornaday/Sinclaire tool by selecting a diameter that is between the shoulder and neck. I've marked that bushing for future use with the WBY rounds.
Sinclair advised no one made WBY-specific bushings at that time.

 

[Varmint Hunter]

Did he change shell holders ? Is it a new batch of brass with thicker neck walls, were the mouths chamfered ?
I've used the Hornaday/Sinclaire tool by selecting a diameter that is between the shoulder and neck. I've marked that bushing for future use with the WBY rounds.
Sinclair advised no one made WBY-specific bushings at that time.

OK - thanks

The brass is well used IMO. No new shell holder that I know of.

I adjusted the RCBS FL die down until it hit my shell holder and set it there for now. I sized 6 cases but it took more effort than it should, and I used an ample amount of Imperial sizing wax. Giving them a brief run in my SS pin tumbler and then will check lengths before I chamfer & deburr.

I wish he dropped off the rifle with the brass and dies. I guess I'll have to go get it before I can get much farther.

 

[RegionRat]

The issue with 300 Weatherby Magnum is they use a 0.4276 diameter to define the shoulder datum on the ammo.
There is a 0.4345 diameter that defines the shoulder datum for the chamber. The tool needs to be near those two values and stay off the radius. Once you have one, it doesn't matter as long as you always use the same one as a comparator.

The belted magnum is supposedly headspaced on the belt, so that first cycle is based on the belt headspace, and there after as reloaders we tend to want sizing to be limited to reliable feed rather than the original size to make the cases last and to control case volume. So, we then tend to want to go to just enough shoulder bump to close the bolt and feed reliably, but then there are diameters to consider.

Brass from a particular chamber needs to be checked for the shoulder datum and diameters after a few cycles to determine how that particular chamber allows the brass to expand.

I am sure you know all this but it bears repeating for the beginners.

The extra work on the sizing die may or may not be due to the same reasons your friend crushed the case. Sometimes the diameter just above the belt at the 0.250 line is not sized well enough by a normal sizing die. In any case, I would suggest you study the diameters as well as the shoulder datum length.

You will want a good micrometer for this task and admittedly this is tricky without what we call a blade mic, but do your best with the round anvil type and see if they look like they are at or over the specs.

I would use the drawings below and study ammo that fits in the chamber, fired unsized brass, and sized brass, to see if you can find a reason. It is always a little difficult to know how any given chamber compares to specifications, but this is the way to start the homework.

If you size and the case fits the gun, that becomes the gold standard.

What part of the case did the die look like it was pushing when it crushed the case? Sometimes it can be seen, sometimes the evidence is destroyed. Sounds like you were able to make it work with a little extra effort. YMMV.

 

[Dr. Vette]

I have used the largest (i.e. size E) comparator insert to reload hundreds of 300 Weatherby rounds. It works OK as long as you stick with the same comparator. Bump it .002 and you're good to go.
Feel free to post the base-to-shoulder length using the Hornady size E. I'm sure I have a rifle I reload for that's similar and can say if you're in the ball park.

To add to what is above, I have found that if the brass is too long, they crush. Some dies catch the edge of the mouth and push it back.
If your Lee collet neck sizer is not set up perfectly, they crush. The collet grabs too quickly, and pushes the whole neck back.

Any idea how many firings each, and if they've ever been annealed?

 

[VenatusDominus]

Like Dr. Vett, I also have used the Hornady size E comparator to measure the bump on my 300 Weatherby loads. I also use a Redding body only die and the Redding competition shell holders to get .002 shoulder bump and then neck size with the Lee collet neck sizer. For what it is worth, I bump my shoulders to 4.390" and this provides a smooth bolt close in my factory rifle. 4.391" has some mild resistance in closing the bolt and 4.392" has significant resistance to bolt closure. Your comparator measurement will likely differ, but should be in the ball park. I anneal before bumping my shoulder with every reload.

 

[Bob Wright]

Definitely, anneal. I get a lot of variation on shoulder bumps without annealing.

 

[Window]

The issue with 300 Weatherby Magnum is they use a 0.4276 diameter to define the shoulder datum on the ammo.
There is a 0.4345 diameter that defines the shoulder datum for the chamber. The tool needs to be near those two values and stay off the radius. Once you have one, it doesn't matter as long as you always use the same one as a comparator.

The belted magnum is supposedly headspaced on the belt, so that first cycle is based on the belt headspace, and there after as reloaders we tend to want sizing to be limited to reliable feed rather than the original size to make the cases last and to control case volume. So, we then tend to want to go to just enough shoulder bump to close the bolt and feed reliably, but then there are diameters to consider.

Brass from a particular chamber needs to be checked for the shoulder datum and diameters after a few cycles to determine how that particular chamber allows the brass to expand.

I am sure you know all this but it bears repeating for the beginners.

The extra work on the sizing die may or may not be due to the same reasons your friend crushed the case. Sometimes the diameter just above the belt at the 0.250 line is not sized well enough by a normal sizing die. In any case, I would suggest you study the diameters as well as the shoulder datum length.

You will want a good micrometer for this task and admittedly this is tricky without what we call a blade mic, but do your best with the round anvil type and see if they look like they are at or over the specs.

I would use the drawings below and study ammo that fits in the chamber, fired unsized brass, and sized brass, to see if you can find a reason. It is always a little difficult to know how any given chamber compares to specifications, but this is the way to start the homework.

If you size and the case fits the gun, that becomes the gold standard.

What part of the case did the die look like it was pushing when it crushed the case? Sometimes it can be seen, sometimes the evidence is destroyed. Sounds like you were able to make it work with a little extra effort. YMMV.

View attachment 395330

RegionRat,

This is great info and thanks for sharing. I've been loading Weatherby rounds for decades and have ran into anomalies that I couldn't explain and you've hit the nail on the head with this one. Thanks again to all the great members on this site for share their knowledge!!

 

[Varmint Hunter]

I don't have the CBTO measurements handy at the moment but here is how things went:

I ran the brass into a RCBS FL die using Imperial sizing wax, but they literally couldn't be pushed in without several partial attempts. In-out, in-out got it done. The brass was grossly oversized in diameter. Case lengths varied so I cut all the cases and then chamfer & deburred the case mouths. I was able to easily chamber each case when I was done. I got everything to the point that they looked ready to reload, however, the primers entered the pockets so easily that the brass would not be safe to use.

It became apparent that the brass was probably shot too hot and too often. I'm waiting to get some once fired brass so that I can get some good measurements and see if the current die adjustments work out.

Thanks for all the tips.

 

[VenatusDominus]

I don't have the CBTO measurements handy at the moment but here is how things went:

I ran the brass into a RCBS FL die using Imperial sizing wax, but they literally couldn't be pushed in without several partial attempts. In-out, in-out got it done. The brass was grossly oversized in diameter. Case lengths varied so I cut all the cases and then chamfer & deburred the case mouths. I was able to easily chamber each case when I was done. I got everything to the point that they looked ready to reload, however, the primers entered the pockets so easily that the brass would not be safe to use.

It became apparent that the brass was probably shot too hot and too often. I'm waiting to get some once fired brass so that I can get some good measurements and see if the current die adjustments work out.

Thanks for all the tips.

FYI, I have found that on some of my more used 300 Weatherby brass, Winchester primers are too loose to use, but the Federal primers are good and snug. I bought the Winchester primers 6 mo ago when it was all I could find, fortunately I was only able to get 200.

 

[Varmint Hunter]

FYI, I have found that on some of my more used 300 Weatherby brass, Winchester primers are too loose to use, but the Federal primers are good and snug. I bought the Winchester primers 6 mo ago when it was all I could find, fortunately I was only able to get 200.

I was using Fed 215 primers which fit snugly in other cases but thanks for the tip. Strange things are sometimes encountered when reloading.