I've never owned or loaded for any mag cartridges except .44 mag and .357 mag. So I was wondering if you gents would be willing to share your tips with me.

By the way, its not my gun. Its for my son in law, but I'm pretty sure he will be having me do his loading.

Thanks in advance.

There is lots of good advice here on this site.

Try starting with at least two different powders, and choose a bullet weight you like. Then choose a bullet specific to your shooting needs.

I shoot heavy for caliber bullets (200-210gr in .308).
So I have powders like Reloader22,Reloader25, H1000,IMR7828,etc.

One thing I would like to say is: DONT load for "maximum" power in your rifle. Load for accuracy, then work on the power factor.
Often enough the "high performance level" yields a better/more consistant load, but not always. Let your rifle tell you what it likes.

Heavy for caliber bullets. (If you don't need heavy bullets, you don't need the 300WM)
H1000 works best in mine.
Get a neck sizer if it's a bolt action.
See if the magazine and chamber will allow longer COL seating.
I find it little fun at the bench, but lots of practice will pay off.
Find a chronograph. Unless you are getting significant velocity over the .30-06, you are better off with the smaller round.

Agreed with the neck sizer, headspacing off of the belt is a poor method IME.
Otherwise the only other tip I have, hold on REALLY tightly

I should have explained better. I don't need help about selecting powders or bullets. I wanted to know if there is any difference in brass set up or in seating. Thanks

I load the 300 like any other bottle neck cartridge. I neck size only without bumping the shoulder and seat about .010" off the lands if I can. The magazine length sometimes limits / determines my OCL with some bullets and I don't crimp. Always works for me.

Thanks Barry

I've refilled several magnum cases from 7mm to .375. Some require FL resizing to feed reliably. Make sure your SIL has a rifle that works predictably with your sizing strategy.

I once made a hunt with a batch of once fired .375 cases, only to find my conservative re-sizing had left me with 6 rounds of ammo that would barely feed, and fourteen that wouldn't let the bolt close. My last 7mm Mag needed a small base die screwed don to the shell holder to feed and cycle.

Oddly enough, many magnum rounds have very broad chamber specs.

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There is nothing really unique about the 300 WM, it has a belt and a short neck, that's about it. For the occasional box of ammo, any brand 2 die set will probably work fine. Since you already know about powder and bullet selection, how much case work do you want to do? I would guess a factory hunting rifle since the 300 mag is useless as a short range bench gun unless you like recoil and burning up powder. If you enjoy loading and want to go the distance: For new cases, sort, check dimensions, run an expander ball through the neck just to get them round and clean up the flash hole. Load with cheap bullets to fire form. BTW, that's the only time I use an expander, even mirror polished, they can and often do change neck concentricity.
Trim the formed cases for length and neck thickness if you have the tools. You can neck size now provided all the cases chamber smoothly. If chambering gets tight, you will need to bump the shoulder and check them. If still tight, might need to size the body just a touch. Unfortunately, nobody builds a perfect die set in a box. I have factory die sets for 300WM made by Redding, RCBS and Forster. I also have a Lee Collet die. For initial sizing, they're all about the same. After that, I use a Redding body die (if needed), a Forster bushing bump die and either a Forster benchrest seater or RCBS gold medal match seater. I will admit I like the RCBS bullet window but they are about the same as a straight neck will generally accept a straight bullet. Lee Collet dies are ok if you like them but I like uniform neck tension based on mechanical dimensions, not how hard I pull the handle and that is a variable with collet dies. Other tools worth mentioning, headspace gauge and bullet jump gauge. There's no point in bumping the shoulder if you don't know how much and shorter bullet jump can improve accuracy although magazine length is more critical for hunting ammo. Maybe more information than you wanted but I'm in a chatty mood...and I think the vast majority of rifles shoot better with good ammo.

I agree TMan, big mags can be brutal on cases and more often then not FL sizing is required to get reloads to feed properly. I just told Jim what works for me in my rifle and the one Jim is loading for may very well need the extra effort for well functioning reloads.

Thanks a lot guys for all the tips. Really appreciated. Now I have to get my back stop repaired and put a new front on it. The old one is just giving out from bullets and weather.

Keep us updated on your progress Jim and good luck.

Well Barry S, I've been loading for a couple dz cartridges, mostly standard stuff, for a bit over 45 years. From time to time I get to un-learn something I was sure I knew.

Usually the .300 Winchester is pretty easy to load for, and I have never had any problems getting multiple .300W's to shoot well. But my last 7mm Mag and my .375 experience taught me to check things out before I unload the truck in a remote section of CO or WY.

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May be a while. I don't think he has bought the rifle yet.

JimboLLN,

I see above some recommendations for a Neck Sizer die.

Well, I have loaded for a number of different 300 Win Mags over the years, and IF your Full Length Dies are properly set up, there is very seldom like VERY seldom a need to waste money on a neck sizing die.

On the 300 W.M., as with ALL bottle neck cartridges, size the minimum amount that will allow brass fired in YOUR chamber to be again chamber in YOUR chamber.

This is done by proper die setup, which means not always following the manufactures directions.

I have written about this subject so many times on the different forums, that I finally made a document on the subject which I will gladly send to anyone requesting the info.

Send me a P.M. with your personal "E" address and I'll glady send it along.

In the document, I quote info directly from a couple manufactures instructions, out lining why one is better then the other and giving the reasons why some printed info is bad.

Learned the lesson years back, that with all bottle neck cartridges you should always set your dies to the minimum amount of sizing to get the job done.

Any more and you are likely to suffer VERY short brass life and a lower level of consistancy.

Also, don't mike braands of brass and as much as possible, buy your brass in larger bulk quanities and all ov one manufacturing LOT NUMBER!

Keep em coming!

Crusty Deary Ol'Coot

Thanks Crusty, I'll send the PM

I'm gonna disagree with you Crusty. I'm sure everybody who has reloaded for a while has tried partial sizing in a FL die. I say it does weird things to brass dimensions but I will concede maybe not all dies do, I haven't tried every brand. If a FL die is used, adjust it the way it was designed to be used. If you don't want to fool with all the gadgets, stay with a 2 die set, they will make good ammo. The downside to a 2 die set is, they generally overwork the neck and expander balls can affect neck concentricity. A cartridge should chamber smoothly with a little room to expand and controlling the amount of expansion is why all the other die types were invented.

Treat it like an overgrown .30-06, forget that it has a belt, and resize your cases based on setting the shoulder back no more than .002-003". If you don't have one, get a Hornady Headspace Gauge set to set up your dies to achieve that measurement. Neck sizing is OK as long as they are being used in the same rifle all the time, but be aware that even then you still will have to full length size after several reloads.

Seating will depend to some extent on how much room you have in the magazine, and how much leade the rifle has. Starting out, just follow the recommended OAL in the manual. You can vary seating depth as you get more experience with the cartridge.

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Guess we will need to agree to disagree on this lumberjak , been there and done that, and because of manufacturing toleriences, simply setting up a set of dies according to the manufactures directions will likely leave you wanting.

Just check out the instructions packed with the Hornady dies if you don't think this is true.

They get it much closer then some other manfactures and come much closer to reality.

Keep em coming!

CDOC

hmmmm...I wonder why Hornady sells neck sizing dies?