Could be "The Dream" - but I've had several .300 mags of various lineage and case, hated every one of them after a very short time, from .308 Norma, .300 Winchester, .300 H&H and .300 Wtby - gues that's 4, not 3.

Disliked the .300 WTBY the most. The amount of powder it took to reach a descent load, compared to the results on game didn't add up to anything I saw as being better than an '06 inside the ranges I used them. The lack of anything I could see of being superior with their added cost of shooting, along with increased sharpness of recoil just did not suit me. I know guys who love their .300's - I simply do not share their opinions in this regard.

I do love the 3/8" bore - metaphorically speaking of course.

The only kinda .300 I do like, is the .311 Express on a #4 Enfield - Ken Waters variety (I didn't know of Ken's round at the time I chambered it up) of the .350 Rem case necked for .303 bullets. Mine runs 174's at 2,960fps - quite easily at that, with 1 1/2" groups using the battle sights. I used a .300 Win mag reamer and "held it back" for the 2.07" chamber, then cut the belt groove with the lathe. It feeds 3 rounds perfectly with a tich of bending on the magazine lips. It isn't any better than the .30/06 however it pleases me to have 'dreamed' it up & chambered it, although it was already around.