Hi
Have made up a batch of 338 rounds and have used standard large rifle primers! It seems many suggest/endorse Magnum primers for this. Will these standard primers rounds be safe to shoot?

Sure it will be safe to shoot as long as you stay within your reloading manuals guide lines for starting and maximum loads listed. I see no reason to use magnum primers as long as your getting the results your after. My 300 Magnum shoots great with federal standard large rifle primers. Magnum primers seem to work best with ball powders in magnum cartridges. Use what it takes to get the job done.

Presume you mean 338 Win Mag. I've done many, many tests with primers and with no exceptions in several rifles chambered for that cartridge the most accurate loads have been with standard rifle primers, particularly Federal 210M's. As a matter of fact with all other elements of cartridge the same, the large magnum primers have been about 10 fps SLOWER. About the only time I'd consider using magnum primers is in super cold weather, or if you use dense ball propellants.

Thanks a million fellas, greatly appreciate your answers. New to the 338 Win Mag..regards
Boris

My 338 isn't picky at all and Fed 210 or 215 shoot equally well with most all loads.

Not only will your .338 WIn Mag loads be safe to shoot when using standard large rifle primers, they MAY perform better.

I have messed with the .338 Win Mag more than probably makes any sense. In my testing I found that I generally had the best luck when loading IMR 4350 if I used a CCI 250 primer. Switching to a Federal 215 primer caused a pretty dramatic pressure increase! (Both are magnum primers)

On the other hand other powders like RL 22 or H 4831 or H 4350 seemed to do well with either one.

But, back to the issue at hand. I did a bunch of tests with several different brands of primers when loading Rl 19 in the .338 Win Mag. In EVERY case, I got better groups and better consistancy on the chronograph when using standard primers vs magnum primers when loading RL 19. (No matter whether the brand was Federal, CCI, Remington, etc.) In some cases I even got higher velocities with the standard primers. Go Figure!

So, I would not worry about the use of standard primers.

R F

Q. What's the difference in "regular" primers and "magnum" primers?

A. The label and the price. The "standard" primer from one manufacturer may have more force than the "magnum" from another.