primers 300 win mag

Can i use large rifle primers # 200 for my rem 300 win mag with retumbo powder?

I always use magnum primers for my 300 WM loads... anyone have any other advice?

Read a bit on the net and it's a toss up.. Maybe chad will chime in

I just know I'm going by published loading data

You can use standard large rifle primers in for loading .300 Win Mag. Magnum primers may or may not work better. The conventional wisdom says that you probably should use magnum primers when loading heavy charges (it's all relative, though...a million shades of gray) of slow-burning powders and especially if it's a "difficult-to-ignite" powder, which I would suppose means ball powders. Some say that magnum primers can improve performance in extremely cold weather.

Use your standard primers, and if you aren't satisfied then try a magnum primer.

If you can get your hands on magnum primers, do so. I've only loaded magnums in my 7 Rem Mag loads with Retumbo, and have never had a fail to fire or a major flier from 30F to 100F. Can't say yay or nay on the standard primers, though.

Win LR Mag primers in my .338 Win

I would use magnum for a 300WM, especially for Retumbo. I use magnum for some 270 Win, 30-06 sized cases, if that tells you anything. If you used a standard primer with a slow burning powder like Retumbo, you can get hang fires. If you were using 4350 or something faster burning, I think it would be ok. But Retumbo, which is a very slow powder, I wouldn't do it. I was having hang fire issues with Retumbo and R25 with a CCI #250 primer in my 338 Lapua ammo. Retumbo in a 300WM tells me you are in the 77 to 85 grains of powder, which is a lot of powder, and getting close to the same amount in a 338 Lapua case.

Also, a CCI #250 primer is between a standard primer and mag primer. It is "rated" as a mag primer, but not as hot as other primers. The 2 hottest primers are the Fed 215 and Rem LR mag primer. This is what I was told to use by the main ATK tech guy on primers for my 338 Lapua ammo. I use the Fed 215 for 99.9% of my mag primer loads.

I use the Federal 215 as my magnum primer too. I'm not saying other magnum primers are bad, just that the 215 has never failed to ignite for me. Consistency seems good too, plus, I still have around 13,000 on hand.

FWIW, Weatherby, Inc. has recommended the Federal 215 for reloading its overbore proprietary cartridges for many decades.