How best to reload a 300 Win Mag

A couple of things -

I no longer own a 300 Win Mag but used to. It was the first cartridge I started loading for when I got into handloading. It is no more difficult or challenging to handloand than any other cartridge. What I found was my Forster Co-Ax press didn't have a sufficiently large opening to reload it without fumbling with bullets during the seating step. I switched to a Redding Ultramag and never had another pinched finger.

If the brass was fired in your gun you can neck size it with the appropriate die and reload it several times before you experience a brass problem or failure. This is especially true if you stay away from the top end of the powder charge scale. But....it was usually near max powder charge where I got the best accuracy.

If the brass was fired in another gun you need to Full Length resize it with the appropriate die.

Annealing the neck and soulder will extend the life of the brass and give you more reloads than not annealing.

IMO - The 300 really shines with 200 grain bullets. My favorite load was a 200 grain bullet over a full case of Retumbo powder and Winchester LR Magnum primers.

A 180 grain bullet is a good choice for a light bullet and some like to use 165 grain bullets too. I would stay away from lighter weight bullets in the 300.

My guess is your gun will have a 1:10 twist because long heavy bullets are common factory fodder.

Don't neck size or partially size. You are asking for problems, especially with ammo you are using for hunting. Get a good set of digital calipers. Buy the Hornady (use to be stoney point) head space gauge set. Use the .420 for the .300 Win. Mag. Get a reading off of a few fired cases shot in your gun. Set your die up to size to HEADSPACE on the SHOULDER(bump it back) .002"-.003" shorter than your fired cases. Your brass will last a long time. You will be surprised in some readings. I had some .300 win. mag. brass that was given to me that had been resized by someone else. It was sized a good .020" short! You don't want to bump the shoulder back more than .005" in a bolt gun.

GET the calipers and the GAUGES. Set your dies up properly. The information given by the mfg. about screwing the die down and turning is NOT accurate.

You can get away with using a drop in cartridge case gauge made by wilson or dillon if you load standard cartridges. But since your loading for a belted case,get the Hornady set of head space gauges. They work with almost any cartridge. They are easy to use. It will be worth it.

Years ago, I was loading for a .338 win. mag. Without using proper gauges (I didn't know any better) I would get about 3 loadings before I got full case head separations. I must have been over sizing the brass to the extreme.

Stay with powders in the IMR 4350 and slower catagory, 4831, IMR 7828, H-1000 etc. and use magnum primers. Lighter charges of mid burning rate powder ( 4064 )may cause hang fires. I had a terrible problem in my 300 Win. with medium burning powders, primers didn't make a difference.

Good luck.

DLB59 said:

Hi everyone. I am going to start hand loading ammo for my 300 Win Mag. I have a buddy who has all the equipment and manuals we will need. However, he has no experience with any 30 calibers and I have no experience period. My rifle is sighted in with 180 grain Nosler Partitions by Federal Premium ammo now and that works really well. It has a 24 inch barrel, but, I am not sure what the twist rate is. It is both my deer and elk gun for the time being. However, I use it primarily on deer. The typical range for deer I will be using it for is around 100 yards, maybe 200 yards, definitely not more than 300 yards for deer. What is the recommendation for powder, primers and bullets. If I do not use partitions I would like to switch to a boat tail of some sort. Thanks.

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I reload the 300 WM. I started with 180 gr Nosler partitions and then tried other bullets such as Sierra spire point, Speer grand slam, and Swift Scirrocco. In my rifle, Ruger 77Mk2, the best accuracy was with the Partitions. The Grand slam and Scirrocco did not fare as well. A variety of powders worked well, including H4831, 4064, 4350. My rifle seemed to be more sensitive to the bullet rather than the powder as far as accuracy was concerned. In fact several powders shot to almost the same point of aim (close enough for most hunting). I found best accuracy as I worked up toward max charges. I loaded 5 of each charge and worked up, found the most accurate load and stuck with it. No need to try for the highest velocity unless it also happens to be the most accurate. I use CCI primers, Federal cases (both brass or nickel). I full length resize and space on the belt. I do not neck size only for hunting loads as I want to be sure of feeding reliably more than the utmost accuracy.
Enjoy your testing and load work. That is satisfying and a lot of fun.

I load for extreme long range but this load is 1/4 moa or better. Berger 210 GR VLD on top of 76 GR of H1000 and CCI Magnum primer. Cases sized till the bolt was hard to shut, then ran the die an 1/8 turn back down and locked it back in. pill loaded to sit .010 off the lands (barely fits in the magazine those VLD are LOOOOONG)

This is going down a krieger #10 MTU tube at 26". 76 GR is on the warm side but no pressure signs. at about 76.5 gr started to see soot on the case neck and lost about 1/4 moa of accuracy and only gained .50 FPS. Like other have said these magnums like near max loads and going over board really doesn't get you much.

Also google "gun juice" it sounds like snake oil but I can attest It take three patches to clean my bore after 20 rounds and brought back a lot of lost accuracy.

190GR matchking would be an excellent pill for what you want. IMO stay away from re22 it burns real hot. The H1000 isn't very temperature sensitive at all which is awesome for hunting, it also meters beautifully.