Magnum Primers?

[doublebarrel]

Are magnum primers required in 300 blackout loads? I found some data that lists them and some doesn't say what primer is used.

[shtgnr]

Not required most of the time. I got my hands on 15,000 of them when primers were scarce so I use them on both subs and supers. I do start a bit lower when working up a load and I have had no issues.

[TX Sapper]

I use CCI 41, which is a magnum primer with a hard cup (for my AR).

Load data varies with just a primer change so be careful. Magnum primers use less powder to get the same velocities.

-Sapper

[rebel]

I use magnums, cci 450's, because of consistant ignition. In my handi I use regular primers because the hammer extension slows lock time and I get ftf issues with the harder cups of 41's and 450's. So I tailor the primer to the rifle I use.

[L1A1Rocker]

If you experience any vertical stringing with your reloads - switching to magnum primers may alleviate this problem.

[doublebarrel]

Thanks for the advice. I've been reloading for 40 years but this is new territory for me. My experience is with lever and bolt guns not semi-auto.

[steven11b]

I have used both types and never seem to notice any speed or consistency differences as in SD/ES. I use fed205 and Remington 7 1/2 99% of the time now in my AR's and they both work well and basically equal performers. This is has been my experience using 400's, 405, fed205 Remington 71/2 in 300blackout loads. One note is I am currently in Texas and it doesn't get below freezing much.

[TX Sapper]

I have used both types and never seem to notice any speed or consistency differences as in SD/ES. I use fed205 and Remington 7 1/2 99% of the time now in my AR's and they both work well and basically equal performers. This is has been my experience using 400's, 405, fed205 Remington 71/2 in 300blackout loads. One note is I am currently in Texas and it doesn't get below freezing much.

It doesn't get below 90 degrees much either!

-Sapper

[tXr]

The 300BLK was designed and intended to use NATO spec primers which are magnum primers. I have seen lower performance with the standard small rifle primers of all makes and they also show pressure signs when there is none. They are also prone to being expelled when fired in supersonic loads that are near max charges.

[Sharkbite]

Some of the powder used in the blackout are harder to ignite in COLD weather. Ive had issues with H110 giving pretty extreme velocity spreads in the winter (Colorado). Switching to mag primers cured this issue