I think I have a donut issue with my Nosler 300 rum brass. Basically, I tried to seat a bullet and it would go in smooth then get real tight at bottom. I had two that the bullet just hit a brick wall and would not seat any further. The brass is 2 or 3x fired. This is my process:
Uniform flash holes and primer pockets if new
Clean necks
Neck size and deprime with Wilson dies
Clean primer pockets
Bump shoulder and body size with Redding die
Trim after each firing
Debur and chamfer
Seat primers
Load
Seat bullets with Wilson dies
So what causes donuts? How can they be avoided? Were they due to loads being too hot or soft brass? Can you get rid of them with expander mandrel?
Thanks,
DoubleG
My son and I each shoot 300 RUMs and we used to have problems getting our rounds to seat comfortably (i.e. without having to crank on the bolt) after 2 or 3 turns of the brass until we made a change to our reloading process. I have had similar problems in my 270 WSMs and 338 LMs. I will explain in detail.
My son uses Nosler and I use Norma brass. My dies are Redding. My reloading process is the same as yours, however, I clean my brass using a tumbler with water, stainless steel media, dish soap (Cascade dishwasher soap and Lemi shine). My primer pockets are as shiny as new and therefore I don't have to clean the primer pockets. I can typically reuse my brass 5 to 6 times before the primer pockets get stretched out and won't hold a primer. I don't think the cleaning and brass preparation described above has a material impact on difficulty seating the round, however, I do believe that de-burring and chamfering the brass is critical for consistency. I use the following tool;
https://www.midwayusa.com/product/211733/lyman-case-prep-xpress-case-prep-center
I like to have a nice bevel on the inside of the case mouth and smooth interface on the outside of the case neck and lip of the brass. I will run my fingernail up the outside of the case neck to ensure that I eliminate any lip. Sometimes I have to turn the brass in the tool that bevels the outside edge multiple times to eliminate any lip. Because I bevel the case mouths every time, I don't find that I ever have to trim my brass. I have a nice case trimmer that I need to sell.
In the 300 RUMs we shoot 230 Gr Berger Hybrid Targets. We use those for hunting and targets (we get good performance out to 2000 meters in the west desert of Utah). I seat the bullet to the Ogive rather than OAL. My seating to Ogive is 2.990". The bullet is seated to where the Ogive is approximately 0.05" from the lands. I cannot seat the bullet to the lands because the rounds won't fit into my magazine. I have a detachable magazine that is super long so that even with the bullet seated to where the Ogive is 2.990" from the base, the bullet is not seated past the case shoulder. I normally like to seat my bullets to the Ogive if the Ogive is a secant Ogive. Fortunately, the Hybrid Burger bullets have secant tapper between the nose of the bullet and just before the bearing surface of the bullet, the ogive switches to tangent. A tangent Ogive is far more forgiving of bullet jump than a secant ogive. I lose a small amount of efficiency (slightly lower G7 BC) but much more forgiving of my poor reloading skills.
There is one big difference in my process and all my round seating (sticky bolt) problems disappeared after I added annealing to my process. I anneal brass after every use before I resize. I don't use an internal button to expand the neck when I am resizing as I do the upstroke on my press. I use the Redding bushing dies and can size my necks so that they have a diameter that is between 0.015" and 0.020" smaller than when a bullet is seated in the brass. Bryan Litz recommended in his books that a 0.015" to 0.020" of neck tension gives him the best performance. To anneal my brass, I use the machine built by Annealing made perfect;
https://www.ampannealing.com/
I de-prime and clean my brass. I then anneal the brass. After annealing I will neck size the brass using a full length bushing die and bump the shoulders back 0.000" to 0.001". The difference between when I anneal and don't anneal my brass is that I find it impossible to consistently achieve a neck size that is 0.015" and 0.020" smaller diameter than when there is a bullet seated in the brass. When I don't anneal my brass before resizing, I have to use a much smaller neck bushing because the brass "springs back" to the fired size. When the brass is annealed, I use a much larger diameter bushing and I hit the proper neck diameter 100% of the time.
I then clean the brass again to remove the case lube and will anneal the brass again. I then de-bur and chamfer the necks. It is probably unnecessary to anneal the necks a second time but the annealer is so easy to use and it takes an extra few minutes to do 100 rounds. There are videos on the Annealing Made Perfect website that are worth watching. The gentlemen in the video are very helpful and respond quickly to email questions. The product is stupid expensive but since I started annealing my brass, my bolts close with little effort. In addition, the Standard Deviation of my muzzle velocities has dropped from > 10 fps to 5 fps to 7 fps.
Annealing made perfect recently made a new version of their machine so that it can anneal 50 bmg. I am thinking of building a 416 Barret and may need to sell my current machine to upside if anyone is interested.
Good luck with your 300 RUM. I love that round. My 300 RUMs outperform my 338 LMs.
