Hello Just started loading for the 300 Win Mag. This is my first belted mag. I’ve fire formed 25 pieces of Nosler brass. It took 3 firings to reach the chamber shoulder. I FL resized pushing the shoulder back 0.002”. I’m on my 5th firing now. How many firings do you get before you anneal? About how many firings are you getting out of your 300 win brass? I haven’t had to trim much at all, in fact some of them are just now getting to trim length.
I usually don’t get rid of my 308 brass until the primer pockets get pretty loose. Do you use the same thing to determine when to start weeding out your brass other than checking for cracks and separation? One last question, I’ve read where it is common on belted mags to get a bulge just in front of the belt where the sizing die doesn’t make contact. Do you see this and does it cause the brass to thin and separate there? Do you use a special die to help eliminate this issue? Thanks in advance for your replies.

I anneal every 3 firings

Pressure is pressure. If you are running 65k psi your brass will not last long. Be it 308 or 300 win mag.

How many firings do you normally get? Thanks

I shoot my belted stuff three times, then throw it away, but I only hunt with mine. One hundred cases will last me years. I full length size, because I have several 300’s. Too much trouble to load for each one. I have several 7 mags and several 264’s. Same for them. Too much trouble to load for each one.

If your brass isn't getting consistant neck tension it's past time to anneal it.

Annealing schedule depends on the level of accuracy you're expecting from the cartridge . Top accuracy comes from ammo that's exactly the same round to round . When a case has been fired 4 times the neck tension is going to be different than it was on the second firing .

You'll get differing answers on these topics just like asking about barrel break in .

You can measure a neck sized case after the first then second firing and see how many firings you can go before the work hardened brass springs back and doesn't give the correct neck tension .

The every three firings sounds pretty good .

Typically I am with hanco on the 3 times then throw them out. I do not do a lot of shooting either, only to sight in and hunt. I found a good accurate load for my 300 and plan to stick with it for awhile. I am on the second loading of about 60 cases right now. I have another 100 once fired, and 100 brand new in the bullpen waiting , so I thinking it will be a decade or 2 before I buy brass and or need to think about annealing.

Thanks Mike. That makes sense, This evening I loaded the brass mentioned in my post, and I could feel a difference in force needed to seat the bullets compared to when the brass was new. There was even a difference from case to case. Neck thickness is the same as a new case. I already resized so I didn’t get a measurement of the OD. So since work hardened brass resists being stretched, annealing before resizing would be the best approach correct?

You're welcome , yes before resizng .

Rugerfan4374 ,

You'll wish you hadn't thrown that brass away when the zombie apocalypse comes .

I really like the 300 win. mag. but I don`t do anything to my brass I just used new brass most of the time,one thing I did start doing was I purchased a lee neck crimp die for my 300 win mag and my groups did get smaller. personally if I play with reloading for a fun project I generally prefer a much smaller caliber/cartridge like maybe 223 rem., 222 rem. or whatever. that recoil on a 300 win mag after a while beats me up to much,i can handle the recoil but it just is not fun all day long.good luck,Pete53

Pete53, I know what you’re saying about the recoil. My 300 has a brake, so it’s very tolerable to shoot. I mix it up though, 308, 223, 17 HMR, even air rifles. I have a very understanding wife. Haha

Rugerfan, what kind of brass are you using? I was surprised to find out Lapua doesn’t make 300 Win. I’d like to get ahold of some RWS brass but I couldn’t find any in tn the US.

I usually get 8-10 loads out of Nosler brass , up to 20 with RWS, I only hunt with 1-2 fired , only because of case separation worries , I anneal after two firings , watch for length and pay attention to neck diameter. Only bump shoulders back .002 ,max Not all cases last the same , even from same lots , most of the cases fail at primer tension not case separation, great thread!

I’ve had 1 or 2 seperate with my 7 mags. That’s why I went to 3 loading, then can it. I bought a 308 for shooting a lot. I’m lucky, my boy has friend in army that brings us 308 and 223 by the 5 gallon bucket full. We do our “shoot em up”Shooting with those. You can shoot 308’s until they split or primer pockets get loose.

I would get a non- belted rifle for banging away. Less for bullets and powder. A 6.5 Creedmoor is a fabulous rifle to fool around with also.

Thanks Bella1, what is your source for the RWS brass? John

hanco , did they separate just in front of the belt?

I get about 6 firing on my brass (300WM). I don't fireform. OP, why did you fireform. Just load the chit and shoot it... I bump the shoulder back .003" when I re-size (belted or not). Like someone else said, your primer pockets will give out way before you get a case head separation, unless your chamber sucks....

Huntington Die Specialty has the RWS brass. Same here anneal after three to five loads depending on how hot they are and make of brass. The 300 and any belted case forget the belt and just bump the shoulder after the second or third firing. With Winchester brass ten loading's is pushing it RWS 15 - 20 is the norm with annealing. The Nosler brass somewhere in between but closer to ten max.

Expansion above the belt will depend on your chamber more than the dies. If this occurs then either a specialty die or chuck the brass. RCBS has small base dies and this collet die is supposed to work well http://www.larrywillis.com/. But if it happens after only a few loadings I might consider a re-chamber job first.

I would neck size or partial size for the first couple of loadings then the 0.002 bump and test how they chamber. Minimal sizing will contribute to accuracy (only some) and definitely longer brass life.

HA HA, well I have something else waiting for the Zombies

I am using Federal Brass at the moment. I have some Remington and Winchester sitting in the closet.

I think you'll be ok then .

I annealed the first 25 cases after 4 firings and will continue every other firing. I noticed 3-4 primer pockets getting a little loose will keep an eye on them might have to cull them out of the heard pretty soon. I wonder, if my head space is set at 0.002, how far the belt is from being fully seated? Or is the belt ever fully seated?