338 RUM vs. 338-300 RUM
1. With 338-300 RUM you have the trouble of necking your brass from 30 to 338 caliber and fireforming. With the 338 RUM just buy your brass and load it, easy. Advantage 338 RUM
2. Price of brass is the same. Just buy 338 RUM brass, easy. Advantage 338 RUM.
3. 338 RUM is simple to reload. 338-300 RUM is trouble necking and loading for a wildcat cartridge. advantage 338 RUM
4. Both send 300 SMK's happily on there way at the same velocities with top accuracy loads with the exact same degree of accuracy. Both even use the same accuracy loads most of the time with 92-93 grains of H-1000 or 95-96 grains of retumbo. You can push both to 2900 fps with a fast 30" barrel or either may get top accuracy in the 2700's. This one is a wash. Take your pick.
5. The 338 RUM feeds better through standard magnum actions with less modification using long 338 caliber bullets. Advantage 338 RUM.
In 2001 when the 338 RUM came out I tested it head to head extensively on my range against the 338-300 RUM I had been doing for 2-3 years. I am an engineer and look at things very logically. There was no logical reason that I could see doing the 338-300 RUM after the 338 RUM came out. After doing many 338-300's in the late 90's I did my last one in 2001. I still have two of those original rifles and they get hardly any work. I always end up shooting my 338 RUM hunting. If the 338-300 gave me an advantage I wouldn't mind wildcatting the brass. I just got the same numbers with both so I go the easy route with the 338 RUM. The 338 Lapua across the weight range of bullets has always shot about 50-75 fps faster than either of the RUM's and the 338-378 wby's 200 fps faster. The lapua probably because of higher pressures with the lapua brass, the wby because it is a monster. At a thousand yards I could kill an elk just as effectively with any of them and include my 28" barrel 340 wby in the mix which shoots the 300 smk at 2735 fps with the best accuracy load.
I know my results continue to offend some guys who shoot the 338-300 RUM and I am sorry because I have no intentions of offending anyone. I just state what my results have been because I have quite a lot of experience with these two cartridges. The 338-300 RUM is a very good cartridge. But it is what it is and gives the shooter no advantage over the 338 RUM that I have found. Both are great long range cartridges. If a guy took a hundred guns in each and worked up loads until he blew the primer pockets out would the 338-300 win the velocity battle by a couple fps with slightly more powder capacity? Maybe. But the fact is they shoot identical numbers with accuracy loads with 90% of each one shooting 2750-2850 fps with 30" barrels. If I had to make a million dollar shot tommorrow it would make no difference to me which one I shot. Take your pick.
I am just reporting results from my personal testing. I welcome anyone to do that and it does not offend me. I look at the data and go from there. I have no favoritism toward any cartridge. I have and shoot many in all calibers.
