300 Win vs 300 RUM vs 30-378 Weatherby

[Fiftydriver]

No that is not true. The 7mm RUM gets a bad rap all the time but its no harder to load for and get good loads then any of the other RUMs. Use the right powders and use a heavy for caliber bullet and you will not have any problems at all.

I would think RL33 would be pretty **** impressive in the 7mm RUM with the 180 gr Bergers. Where most get into trouble with the 7mm RUM is that they shoot to light of a bullet. You need to use at least 160 gr bullets and heavier the better to get the best velocity spreads. If someone wants to shoot a 140 gr bullet, get an STW or Rem Mag.

Another thing people do is think they can get extreme velocity with the 7mm RUM by using the lighter weight bullets. This is true but generally, the powders that work best in the 7mm RUM DO NOT care for lighter bullets and will produce much better consistency with heavier bullets.

Plus, light weight bullets do great out to moderate ranges but past around 600 yards, there is no comparision between them and the heavy for caliber bullets. Let the bullet do the work for you, its easier on the rifle and brass!!!

Finally, one has to understand that the 7mm RUM is a very low expansion ratio chambering, as such, limit shot strings to three shots and no more without letting barrel cool and clean often.

Most of the bad press with the 7mm RUM is opinion or someone that is not using it correctly or loading for it properly.

That said, for an all around chambering, the 300 RUM is a more flexible chambering for sure. Is it a BETTER choice, depends on what you want to do with the rifle.

 

[Trickymissfit]

Very close. I do not know the exact dimensions on the 338 RCM but they have to be very close.

Wyatts makes a 3.000" extended mag box that you can install that offers enough length for the 338 WSM but with tipped bullets or match bullets, its VERY tight and you really have to pay attention to your throat design to be able to reach the lands and still fit in the mag but it can be done.

I built a browning earlier this year in a 338 WSM with a very short throat and it worked very well with the 200 and 225 gr Accubonds.

now I'm big on the good old .338-06 improved. I have the donor sitting in my safe right now, and just gotta get the time. The .338RCM fascinates me. It'll push a 225 grain bullet to a little over 2600fps with an over all length of 2.83". That's close to a .308 Winchester! But I suspect that the round is good for 2750 fps! That's .338-06AI velocity in a short action. A sure fire win win in my book
gary

 

[Sral1987]

not a flame, as I really don't car that much.

Virtually all the big mags are overbore from the start. the Ultra mag and the 30-378 are borderline ridiculous. Lots of powder for maybe 170fps at best. The Op never said what kind of bullets he was thinking about using, and I just grabbed two manuals for a quick scan.

In the Hornaday manual using 190 grain bullets (I didn't have any load data on the Sierra 220 and 240 grain bullets to go by), I was kinda stunned at what I saw in there:

* .300 Rem short action ultra mag will do 2900 fps with 62 grains of 4350 in
a 24" barrel!!

* .308 Norma mag will do 3000fps using 73 grains of RL22 in a 24" barrel

* .300WSM will do 2900fps with 74 grains of Magpro and a 24" barrel

* .300 Win mag will do 2900fps using 68.6 grains of 4831 and a 25" barrel

* .300 WBY mag will do 3100 fps using 75.7 grains of 4831 in a 26" barrel

* .300 Ultra mag will do 3200 fps using 92.3 grains of H1000 and a 26" barrel

* 30/.378 will do 3200 using 114 grains of 8700 an a 28" barrel

now what we see here is that when the barrel lengths are somewhat close to being equal the only thing that's happening is making Hogdons and AA richer! Maybe if you had a 34" barrel you might pick up 250 to 300fps, but you'll also need a number one gun bearer to carry that thing! The .308 Norma mag just steps out and says "I can!" Of all these rounds it's common knowledge that the Norma mag thru the .300 WBY are by far the most accurate in very long distance shooting. The short action Remington looks to be a fairly good case design, and also very efficient. Same could be said of the .300WSM. The .300 WBY, .300 Ackley mag, or the Jarrett are the best in case design, but starting to show some serious overbore unless you move up to the 220 thru 250 grain bullets and a 28" barrel. All three are known to be very accurate in the right chambered barrel. Plus they have by far the best shoulder neck design (throw the WSM in that mix as well). The ultra mag beside burning a bunch more powder has the issue of the T.P. point out on the lip of the case. Meaning a short throat life. Still if your somebody like Dan Lilja (a fine gentleman I might add) this means little. For me it would.

The .300 Win mag would be the cheapest of the bunch to get into as cases are cheaper. Still you could make Norma cases out of Win mag brass! The Ackley and Jarrett can easily be formed from either necking up 7mm STW brass, or necking down 8mm mag brass. Easy enough to do. The .300 WBY brass is a go from the start. But once again I'd start with a .300WSM, or do a low free bore chamber in the WBY (all will have free bore in a factory barrel!)

What we see is very diminishing returns for as much as 33% more powder in the big cased mags.
gary

What you say here is certainly true, the efficiency goes down past the winmag by a lot! A velocity advantage of 900 feet a second from a .308 to a .30-378 bascially only means that the .30-378 will do anything the .308 does just about 300 yards farther ...

 

[Aoudad shooter1975]

Depends on what you want to do where. I have owned 2 30-378 accumarks--they both were 1.5 in guns...cut them into 300 Norma's and they shot great...that is not to say that a 30-378 would not be Incredible. I ran 210 berger at a bit over 3050...fairly easy and 230s 2875 "ish" incredible hammer in a accurate rifle. If I were you if I handloaded...300 rum, if I bought ammo off the shelf 300 win...and if I wanted to yank my hair out--and spend tons of money...then by all means....

 

[Sral1987]

If you cannot do it with a .300 winmag a .30-378 wont be able to do it as well ... thats the truth.