I have been shooting and reloading the same 20 cases for my model 70 300WSM with starting loads of 150 and 130 grain bullets to get a feel for the rifle and see how the brass held up. I just trimmed all 20 and loaded them for the 5th time. I was surprised to find that 3 of 20 split their necks on this firing. Seems like short brass life for nowhere near max loads? I measured a couple of fired cases and they go .344 outside with .017 thick neck walls. This was done with calipers not a micrometer so its not as precise as it should be but shows no evidence of an oversize neck that might be overworking the brass. Any ideas? Should I try annealing the necks after 3 or 4 loadings?

Neck splits have nothing to do with light or heavy loads. They are usually the result of work hardening the necks. That comes from overworking the brass. You can alleviate this in several ways if that be the case. You've measured your fired case. Take a fired case and size it without the expander in the die. Measure that. If the difference between the sized and unsized case is more than .011"-.012", your are overworking the brass. Possible you can alleviate this by chucking the expander ball in a drill and polishing it down some. For this operation measure the neck of a round with a bullet seated. Measure the neck of sized round before the bullet is seated. The difference in the two measurements should be about .002" or a bit more, maybe .003". If your measurements are in the ballpark, then you need to return the die to the manufacturer and have them polish out the neck a bit. Call them. They will probably ask you to return it with two unfired cases.

You can prevent the neck splits by annealing the necks. I routinely do it every 4 or 5 reloads in spite of neck sizing most of my reloads. Not only will you have the benefit of preventing the neck splits but you will also get more consistent "grip" on the bullet and improve your accuracy.

Kevin,
I started learning about cleaning my rifles after experiencing split necks with few reloadings. The best info to pass along on that issue would be -- get the Sinclair book ("Precision Reloading", I think) and follow their cleaning approach.

wthbymag

Wow, I am surprised with that caliber, you made it to 5 loads accurately. With my 300RUM, I am lucky to get 3 maybe 4 loads and accuracy seems to fall off after 2 loads.

I reloaded for quite a few calibers and haven't had any split necks yet. The only time I've seen split necks were 3 rounds of Winchester Factory .30-30 ammo from a box of 20rds.

Brandon

All refer to the diameter of the necks. Measure a fired round. Write that down. Measure a sized case which is sized WITHOUT any expander in it. Subtract that, and if the difference is .011" or less you are fine. If it's any more, the neck is sized down too much before it has to be expanded by the expander coming out. It just gets worked much more than it needs to in that case.

What they do is make the expander bigger if they are down sizing the neck too much and that work hardening causes premature splits.

The other measurement with a sized case versus with a bullet seated is the "grip" on the bullet. You need minimum .002" to prevent setback in the magazine when a round is fired. That's about ideal for the heavier kickers. .003" is OK but borderline too much. If it's any more than that the die needs to be reworked by the manufacuturer.

Thank you Bob338. I measured a fired case at .345. I then resized a case having removed the expander first and it measured .320 . You were correct, the die is sizing the neck down too far. If I subtract out the neck wall thickness times two (.033) the inside diameter of a resized case is down to .287 before the expander (.307) is getting dragged back through it. Time to order some Redding Bushing dies.

Not an uncommon problem. Glad you got to the source. Whose dies are they?

You might consider returning the die to the maker. They will either replace (likely,) or try to polish out the neck, though trying to remove that much material they will get past the hardening, plus it's likely to be egg shaped unless they bore it and heat treat it after. But you are better off with a better die.

I have had a lot of trouble with Win. 300 WSM brass it is hard than hammered hell. The necks did split becuase it is hard and you were over working it. I only get five to six firings on WSM brass, but I have never had a split neck. The brass is hard and after that many firings it was springing back after to going through the sizing die (Redding Type S with approriate bushing) The primer pockets were on the loose side right out of the bag. I was really surprised at the poor quality of the WSM brass as I have had excellent results with Win. brass in 223 and the 308. Went to Norma brass for the WSM and that was the end of the problem. But you can't over work any manufactures brass or failures will occur.

Shoot Safe, Shoot Straight....RiverRat

Bob338,
Thank you for the very professional info on the neck splits!!! Would you divulge your neck annealing procedure?? I am full length resizing a beltless case just enough for the round to bolt without requiring excess downward bolt force to chamber. Being an old "Neck Sizer Only", I have no annealing experience and thought it may be a good idea. Appreciate any info.

ESteele, check your E-mail.

My experience with 300 WSM brass isn't the same as posted here. I've used W-W 300 WSM brass expanded to 338 for a 338 WSM I have. For grins I bought 50 cases each of Norma and W-W when I had to make some more cases.

The Norma cases are much more expensive. Having had great luck using Norma brass in other chamberings I expected it to (1), be more uniform than the W-W, and (2), to be much lighter than the W-W. I found neither. The first lot of W-W I got averaged 219g per case with a weight spread of about �2g. The second batch of W-W that I recently acquired averaged 228g per case with a spread of about 2.5g. The Norma brass averaged 251g per case with one case weighing 259g, the rest with a spread of �2.5g. The wall thickness was about .001" more on the Norma and while I haven't split a case to check the dimensions on the head, the majority of the weight seems to be down there. I see little advantage in paying more for significantly different brass that isn't near the same and is not better than the W-W stuff. To top it off the water capacity of the Norma is about 2g LESS than W-W, meaning you'll reach higher pressures earlier than with W-W. I think the W-W brass is much better for the WSM.

Bob338,
Again, some good info, but I'm the guy who asked how to anneal cases.

Sent a memo to the E-mail address you have in your profile. If that's incorrect contact me directly and I'll send it to you. It's not the first time I've been asked. Happy to give you the info, but it's long. I use a propane torch twirling the brass in my fingers and drop it into a bucket of water.

Bob338,
Thanks for the E-mail and very well written instructions. Will practice on some old cases as soon as possible. Thanks again!

The dies were Lee. The redding full-length bushing dies were what I was going to try next.

KevinNY,

Split necks usually happen when a case becomes work harden and are fired in a chamber with a large neck area. The pressure of the loads will contribute to the problem. The only solution I know of is to anneal the case necks before they are fired the first time. I do not anneal cases because I think it is too easy to do it wrong. Good luck.