.300 RUM or .30-.378

If you had a single shot action laying around and you were going to put a rifle together in one of the two cartridges listed above which would you pick and why?
Assume throated for Berger 245s and a 28 or 30 inch barrel. Would be for some hunting but mostly just playing.
It appears even with the extra case capacity of the .30-.378 there is not a lot of difference in velocity. The .300 Rum has better brass availability and my guess is dies are cheaper.

IMO you've already answered your question correctly. The 300 RUM has brass, dies, and ammo advantages. Easy button.

For the heavy weights 230, 245 the 30/378 with 28, 30" will perform better with the right powder.
I have both, I am a Rum Fan but I would recommend a 30/378.
You didn't say what bolt face you have, they are different.

RUM simply because because much better brass is available.

built many rums and edges and the case is extremely accurate. h1000 is the ticket. reloading components are easy to come by with many brand options. i haven't built or owned a 30/378. don't just look at speed charts

Left Hand Dave said:

If you had a single shot action laying around and you were going to put a rifle together in one of the two cartridges listed above which would you pick and why?
Assume throated for Berger 245s and a 28 or 30 inch barrel. Would be for some hunting but mostly just playing.
It appears even with the extra case capacity of the .30-.378 there is not a lot of difference in velocity. The .300 Rum has better brass availability and my guess is dies are cheaper.

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If the goal is to propel the 245 Berger fast, "I" would go with the .30-378 WBY. Depending on source, the WBY has ~23g H2O capacity advantage over RUM. The cost of dies are about the same. The RUM has the advantage in max pressure. "I" would still favor the WBY.

Well if you want to discuss the accuracy factor, consider that the late Earl Chronister set a new 1000 yd. heavy gun record at Williamsport in 1986 of about 4" for the 10 shots.
He used a 30x378 built on a Howard Wolfe action, with 250 gr. Sierra Match Kings.
And yes Sierra did make the 250s for a short period of time before they settled on the 240 gr.
Check the size of the current heavy gun record now almost 40 years later and compare it to Earls with the 30x378.
I used a 30x378 for long range hunting for many years.
My advice today for 30 caliber would be to use a 300 Win Mag or a 300 Norma, and for the longer distances go for a 338 cartridge capable of producing 3000 fps or more with a 300 gr bullet.

K.E.C. Darkside said:

For the heavy weights 230, 245 the 30/378 with 28, 30" will perform better with the right powder.
I have both, I am a Rum Fan but I would recommend a 30/378.
You didn't say what bolt face you have, they are different.

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I don't think the bolt face would be an issue as long as someone makes a the correct bolt face for the Savage 112 Magnum Target. I guess I did assume that action would be compatible with the .30-.378 but you know what they say about assuming.

If you look closely at a 300 Rum case you will find that the head of the case is rebated so as to fit a standard size magnum bolt.
My first 30x378 was built on a Hart #4 custom single shot action with a standard size magnum bolt face.
We used 338x378 Wby brass necked down to 30 cal, as the 30x378 brass wasent available at that time.
And we turned down the case heads so they fit a standard magnum bolt face.
The head of a case is solid brass, the heads of the larger diameter cases is simply more solid brass.
But that was back then, and this it now, when better options are available to us.
And a better option for any large capacity case like the 30x378 is one of the many custom actions available today.
I am a very old fan of Savage rifles, i currently own five of them.
But i wouldnt even consider building a 30x378 or a 300 Rum either on one of their actions.

In the 30 cal range, I have 308/26-Nosler (a bit bigger than 30 Nosler) and 300 RUM. The RUM is a 30" Bench Rest on a R700 accurized action. I have not made 4" 1000 yard groups.

I would choose the 300 RUM. "Practicality" over absolute speed. The why is below.

"There is no replacement for displacement" is true to an extent. Ballistics, like motorsports reaches a point of diminishing returns.

Case capacity and fps with 28", 245 Sierra: using QL and "knowledge" of shooting chamberings close to....
Approximately:
30-378 133 = 2950 fps
300 RUM 112.5 = 2850 fps
30 Nosler 99 = 2750 fps

Each step down is worth about 100fps with the same bullet at about the same PSI and "optimal" powder and charge. Not most accurate. Not the best COAL. Just "same" to "same". Can you "go faster", sure.

so, to me...

The 300 RUM is practical in most magnum class long actions, has the speed to reach 1000 "easy" and 1 mile practically.

If you already have the single feed action, please share which one and the bolt face and maximum COAL it handle.

Hard do advise without data.

Rum for the brass, I don't like Norma brass. I find it soft.

HSmithTX said:

Rum for the brass, I don't like Norma brass. I find it soft.

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WBY has several sources for their brass, other than Norma.

FEENIX said:

WBY has several sources for their brass, other than Norma.

View attachment 625836

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OK, good to know, everything I have seen personally has been Norma.

HSmithTX said:

OK, good to know, everything I have seen personally has been Norma.

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I have a .257 WBY but not sure who the source was, but I do not have any issues.