Are you crimping the bullets? If so, do not do it in the same step as seating.

Aha! Nice catch, Steve. I hadn't thought of that....I am using a standard RCBS die set. I bet I have the die set too low.

Try chamfering the inside of the case mouth slightly this has helped me. Most rifle loads do not need any type of a crimp except for 30-30's IMHO.
Good luck.

Gents...

I am having some trouble with some 300 Weatherby loads I cooked up. I don't believe the load data is pertinent here, but for the heck of it, I used 168gr Barnes TSX, 180gr Barnes TSX, and 200gr Nosler Partitions.

Approximately 2/3 of about 60 rounds had crushed cases. I did not notice until I got out to the range. The case looked as if the top had been compressed downward, resulting in a circular bulge right below the shoulder. All of these rounds chambered, some of them took a little bit of muscle. I fired most of them, to get the cases back to normal.

How did this happen? I don't believe it could have happened during the sizing operation, as the sizing die, well, sizes, the case correctly.
My theory would be that I seated the bullets with too swift a stroke, hence compressing downward on the case.
To preclude this from happening in the future, I have, just yesterday, started to polish the insides of the necks. I guess I'll be a bit softer on bullet seating, too.

What's your educated guesstimate on this situation?

I did it with a 7mm TCU once right before a silhouette match. The cases were just crushed enough such that about 25% wouldn't chamber and the rest were a little stiff. It was because the die was adjusted too low, just enough so that minor differences in case length gave a slight amount of bulge at the shoulder. It was almost impossible to see unless you rolled them against something flat at eye level.

Ok I totally agree with the diagnosis but have one question. How the hell do you crush that many cases and not notice it before you get to the range, do you make a habit of drinking and reloading?

It is a very light crush...hardly noticable on such a large case.

Seating flat based bullets can sometimes catch on one
side of the neck and cause a wrinkle just below the
shoulder. 348 Win, 3030, Wbys, and some other thin
walled cases. I use a Lee universal case neck expander
to put a very small bell on the mouth of the case.
The taper crimp feature in the seating die will
take this out, but dont set it too tight or you will
create another problem. I got started with the lee expander
when loading a lot of Barnes XLC coated bullets.
I was having problems with scraping the coating off.
Now I use it almost all the time when loading flatbased bullets.
The main thing is keep the bell as small as possible.
It sure makes seating bullets smooth.
Lyle

Thanks guys...I will give that a try as well.