.243Win with Ramshot Magnum - run Mag primers?

[Mikey_B79]

So I finally got my butt out to the range to do some testing on a. 243 Winchester load I've been working on. I'm using Nosler data for Ramshot Magnum with regular 210 Large Rifle primers. Working up in half grain increments from 48.5 to 50.5 have the following results (20" barrel, 5-shot sample sizes) with the 95 grain Ballistic Tip:

48.5gr - 2789fps - SD 27.2 - ES 49
49.0gr - 2816fps - SD 11.8 - ES 21
49.5gr - 2837fps - SD 31.9 - ES 63
50.0gr - 2881fps - SD 25.5 - ES 48
50.5gr - 2838fps - SD 21.3 - ES 42

Even though I've loaded them out a bit longer than the book data (to SAAMI max OAL) the load is most definitely still compressed on the top end. I've been told Magnum doesn't *actually* need a Magnum primer to light it off, but compressed ball powders are notoriously hard to ignite properly. I've got 200 RWS 5333 Magnum primers sitting here and a bunch of prepped brass, I'm thinking of dropping back to 48.0 grains and retrying the ladder.

Has anyone else run into anything like this? I'm sure I'm not the first. The case fill and outright velocity with Magnum is pretty sexy but the poor consistency is leading me to think either 1- time for Magnum primers, or 2- time to crack open this Kg of N555 and try again.

 

[JK47]

I was gonna say, I would try the mag primers and work around that 49 grain rung. The extra heat/spark from the mag primer will probably help that caseful of powder burn more even/efficient. Probably gain a few fps, and hopefully bring the SD down into the single digits. I would try 48.8 and 49.2 grains as well.

If it spreads back out, I would try a little faster powder.

Disclaimer: I’m no master loader, as I taught myself with few resources when I started, but when I have good groups and consistent velocity, I don’t push it and try to get 50-100 more fps. I settle on what the gun tells me it likes.