Please note that this article looks at research and testing done by a variety of sources. Extreme caution should be taken when creating loads that go against accepted load data. This article looks at theory and our experience, and should not be considered recommendations about primers for 300 Win Mag Reloads. When developing a new load for your 300 Win Mag, or any caliber, you should start with smaller amounts of powder and pressure and work up gradually. Always follow safe reloading practices.
What size primer does 300 Win Mag take?
300 Win Mag is short for 300 Winchester Magnum. The 300 Win Mag takes a Magnum Large Rifle primer, though some have experimented with regular large rifle primers. Most all load data though recommends that you use a large rifle magnum primer, but experimentation may lead you to other preferences.
Hornady Reloading Manual
Best 300 Win Mag Primers
There really isn’t a best primer for the 300 Win Mag that can be universally applied to all guns. Different guns like different powders, pressures, projectiles, and primers, though in our experience the primers had the smallest change in standard deviation of these variables. Our favorite are either the Federal match grade large rifle magnum primers or the CCI magnum primers.
Berger Reloading Manual
Non Magnum Primers in 300 Win Mag
Can You Use Non Magnum Primers in 300 Win Mag?
Magnum primers are generally hotter and faster and ignite the powder faster, so why would you consider a non magnum large rifle primer instead? A non magnum primer may just be more accurate. Sometimes the slower burn rate and the lower pressures are what works best for your rifle. When you’re trying to get sub MOA or sub .5 MOA, it’s worth trying. I’ve seen reports and pictures on forums of guys really tightening up their groupings with the non magnum large rifle primers, and guys that have it hurt their groupings. Best thing to do? Load some up side by side and see what your gun likes.
Large Rifle Primers for 300 Win Mag
- Federal 210
- Winchester Large Rifle
- CCI 200
300 Win Mag Specs
Which Federal Primer for 300 Win Mag?
Federal 215, which is the large rifle magnum primer, or the Federal 210, which is the regular large rifle primer, depending on what your gun likes. You can also get their match large rifle magnums or match large rifles.
Which CCI Primer for 300 Win Mag?
CCI 250 Primers
This is CCI’s large rifle magnum primer and is probably the most popular primer used for the 300 win mag.
CCI 200 Primers
CCI 200’s are the large rifle primer, not a magnum.
CCI BR2 Primers
If your gun likes large rifle primers instead of large rifle magnums, then CCI BR2 primers are a good way to go. They are essentially a match grade large rifle primer, but they are not a magnum. Unfortunately, CCI doesn’t make a match quality magnum primer. Federal does if you’re looking for match grade.
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