I read on a forum awhile ago that some guys where using large rifle primers in there 300 win mag casings instead of magnum primers to get more a more consistent velocity. They reported having a a higher and more consistent velocity on average. Is this something that is safe to do? I'm assuming you would want to start at the start charge or maybe even below it to check for pressure signs. Has anyone had experience with this and if so, what are the pros and cons for using large rifle primers over magnum primers?
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Large rifle vs magnum primers for 300 win mag
Large rifle vs magnum primers for 300 win mag
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Update: I finally did a test using a 220 grain eldx load out of with 300 win mag. 65 grans of rl22 and a seat depth of 3.425".
I accidentally primed a few mag primers in my 25-06. I loaded them to compare with the large rifle primer. I noticed a 1.5 inch higher group with the mag primer.I also noticed the primers flattened a bit more.
Another side to the primer question is outside temperature. If you shoot in very cold temperatures it was recommended to use magnum primers even in 30-06 cases. ( Bob Hagel in his book). We are talking decades ago, and I never tested it myself. Not sure if that theory still stands or not or how much it had been experimented with.
The F215 primer was designed for the .378 Weatherby and similar big case. once I switched to CCI 250 primers in my .300 WBY I got a marked improvement in grouping.
I’ve tried both in my .270 mag primers I think have a better ignition for bigger calibers and I wouldn’t use anything but a mag primer in any magnum 😊
I use federal 210m instead of 215m in my .300 win mag with zero pressure signs and pretty much consistent velocities.
Generally speaking you will get higher pressure and velocity with mag primers.
Some people get more consistency with standard primers, very seldom if ever would you get higher velocity.
You should be OK going from mag primers to standard. You get more pressure when you go from a standard to a mag primer in a load.
Do you have the ability to try both out?