Hello all this is my first post on this forum. I plan on doing some
reloading for the .300 Win mag. My question is what primer should be used in
the .300 Win? I have a few different reloading manuals and each one says something different.
My latest Hornady manual says use Winchester Large Rifle Magnum primers,
while my latest Lyman book says use Standard Large Rifle.
I plan on useing Hornady A-max 155 grain. IMR 4350, IMR 4831 With Federal Nickle Cases.
Thanks for the help.

I use standard large rifle primers in mine. Never had a bit of trouble

While the previous poster always used standard large primers, I never put anything but magnum primers in mine.

I would recommend either the CCI 250 or Fed 215M primer for this cartridge. That is a fairly large case and you need a good fire under it to start ignition.

The only powder I would recommend using a standard primer with in any case is RL 19. For some reason this powder does better with standard large rifle primers.

It is worth to do some testing between primer brands and type (std. or Mag) as the rifle will have its own preference.

I have 2 .300 Win Mag rifles. My Blaser R93 insists on CCI 250 and hates WLR Mag primers. OTOH, my Rem Sendero shoots as accurately with both (same POI too).

Also, my Sauer 202 in 7x64 thrives on CCI 250 + N 160 but vertically elongates groups if I substitute WLR standard. Same rifle with .30-06 bbl. loves the latter ?!?

quote:

Originally posted by Win38-55:
Hello all this is my first post on this forum. I plan on doing some
reloading for the .300 Win mag. My question is what primer should be used in
the .300 Win? I have a few different reloading manuals and each one says something different.
My latest Hornady manual says use Winchester Large Rifle Magnum primers,
while my latest Lyman book says use Standard Large Rifle.
I plan on useing Hornady A-max 155 grain. IMR 4350, IMR 4831 With Federal Nickle Cases.
Thanks for the help.

Every thing I load for from 22-250 to 458WM gets a mag primer. CCI 250 or fed 215

If its got a belt on it, it gets a magnum primer. They might not need them but it gives me a secure feeling.

nothing but mags in a mag for me. I hunt alot in cold weather and a std primer might light off a bunch of slow burning powder in the summer but take it out in the cold and watch your chrongraph readings change. I use all the differnt mag primers but if i had to stock just one it would probably be the feds.

wrlm

Welcome to the AR forums Win38-55.

I use mag primers in large volume cases and a .300 WM is a great candidate for a mag primer.

Hello
I've used Win large rifle primers, WLR, behind IMR4350 and 180gr bullets for years with good results. WLR primers are the 'hottest' of the 'standard' primers.

However, if you start using a 'ball' powder like H-1000 or something similar, you would want to use a magnum primer. Ball powders generally prefer a hotter primer, especially in cold weather.

In the process of tuning a rifle, trying different primers is a matter of coarse. Some experiementation is necessary. Every rifle is different and there is no way to predict what it will prefer.. Good luck

I have "always" used magnum primers in magnum cases....except when I didn't. Which is never now, after I had a squib in 458 Winchester magnum with a standard primer.

Win38-55 ----- I have shot many thousands of rounds of .300 Win mag as has 8 of my Elk hunting buddies. We all use the Fed 210M primer. If I use the Mag primer, which I use for all other Magnum chamberings I shoot, I blow my group to 1-inch from one hole. We hunt Colorado in the 4th season, which is very cold and snowy with no problems. Good shooting.

As you can see from the responses, you'll have to experiment.

Both my .300's get better accuracy with the WLRM.

I even get better accuracy with the mag primer in some standard cartridges.