Yes, but you can shoot it with mid pressure loads while fireforming brass. My rifle shoots great with virgin unformed brass. Just can’t run loads anywhere near max when fireforming. And like Alex said, a barrel really doesn’t calm down and come into its prime until after the first hundred rounds or so.
The difference between the 300 Norma and 300 NMI is pretty significant as well. The standard 300 Norma isn’t going to perform much better than a 300 PRC or the Nosler cases. If I had to choose between the PRC and standard Norma, I’d keep it simple and use the PRC because I wouldn’t be losing much.
But when you add 7gr of increased capacity by going NMI and fill it full of Vihtavouri N570, now you’ve got one hell of a mean animal on your hands
The standard Norma with Lapua brass has about 102-102.5gr of H20 capacity. My NMI with straightened body and 35 deg shoulder in Lapua brass has 109-109.5gr of capacity. That’s a pretty significant increase of around 7gr.
Standard Norma on the left, Fireformed 300 NMI w/35 deg shoulder on the right.
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