I'm wanting to build a 30 caliber magnum and I keep waffling back and forth over just sticking with a tried & true 300 Win Mag, throated long, 30 Nosler throated long or 300 Norma mag (or improved).
I ran some hypothetical numbers through Quickload, all using 230 Hybrids, N570 powder and a 26" barrel. For those of you that are familiar with QL I used the same weighting factor of .5 even though the Nosler and Norma are probably more overbore than the 300 Win Mag.
I was quite surprised to see how little difference there was in velocity.
- 300 Win Mag - 83.3 grains - expected velocity 2,940fps
- 30 Nosler - 88.4 grains - expected velocity 2987 fps (6.12% powder increase, 1.6% velocity increase)
- 300 Norma - 90.2 grains - expected velocity 2991fps (8.28% powder increase, 1.73% velocity increase)
- 300 Norma Mag Improved - 94.5 grains - expected velocity 3009 fps (13.45% powder increase, 2.35% velocity increase)
Keep in mind the 300 WM & the 300 Norma have a lower listed max pressure than the Nosler so I'm sure that contributes to their lower velocities.
I would like to hear from folks that have a 300 Norma or 300 NMI as to what real velocities your are seeing when using the 230 Hybrids.
I'm trying to decide if the modest velocity gain (calculated) is worth the extra cost of the Lapua receiver, brass and the recoil penalty over the old school 300 Win Mag.
If the Norma is more overbore and I change the weighting factor to .4, the spread jumps quite a bit. 300 NMI - 95.6 grains - expected velocity jumps to 3068fps (14.77% more powder, 4.35% velocity increase).
That's 128fps faster than the 300 Win Mag but at the expense of 12.3 more grains of powder.
Thoughts?