I'm looking for a new elk rifle and I was thinking of a 300 RUM but I ran across this 358 UMT and I read that it's faster than a 300 win mag. and shoots flatter than a 7mm. does anybody know about this cal. I did some looking and found this. Home » Technical » Product News » Publication Mentions » Shooting Illustrated Shooting Illustrated Shooting Illustrated March 2005 Home Grown By Bryce Towsley Unlike most of the American big game hunting public I have always been a fan of .35 caliber rifles. Physics is physics and big bullets simply hit harder. The downside, even in cartridges like the .35 Whelen, has been a trajectory that is too curved by today’s magnum-loving standards. But when Remington brought out the .300 Ultra Mag in 1999, I saw an opportunity. Even though they had plans for a family of cartridges based on the parent case, I knew it would be a long wait for a .35, so I built my own. I decided to keep it simple and necked the .300 RUM case up to .358 with no other changes. It maintains the same body taper, the same 30-degree shoulder and the same datum line for headspacing. The only difference is a larger, slightly shorter neck and the resulting shorter shoulder. I called the new cartridge the .358 Ultra Mag Towsley (UMT). The .358 UMT shoots flatter than a 7mm Remington Magnum with a 160-grain bullet or a .300 Winchester with a 180-grain bullet. In the .358 UMT a Nosler Partition 225-grain bullet at 3,225 feet per second that’s zeroed for 200 yards is only 5.72 inches low at 300 yards. The .300 Win Mag with the same zero is 7.60 inches low at 300 yards and the 7mm Rem Mag drops 7.24 inches. The .358 UMT with a 250-grain bullet produces 5,388 foot-pounds of muzzle energy. That is over 1,000 foot-pounds more muzzle energy than the .375 H&H 300-grain factory load. The .358 UMT has more energy than the .416 Remington 400-grain factory load at any range, including at the muzzle. At 100 yards it still has more energy than the .375 H&H has at the muzzle and at 200 yards it retains 3,676 ft-lbs, almost as much as the .338 Win Mag has at the muzzle.