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jim boyd's picture
Grand Slam Challenge Winner!
Joined: 07/06/2010
Posts: 889
300 Winchester Ultra Mag

Hello Folks -

We all know some lucky BGH member is going to own one of these 300 Remington Ultra Mag - or 300 RUM...

I admit now knowing anything about this cartridge, so I did some research...

It is a BEAST!

Below is a photo of a .308 WIN, 30.06, 300 Weatherby and a 300 RUM... just look at the cartridge size difference.

With recoils of the 7mm-08, 308 WIN and 30-06 - all throwing 140 - 150 grain bullets in the 10.8 to 11.9 (foot pounds? is that how these are rated), the 300 RUM is up in the low 30's if I read the chart correctly!

Throwing a 150 grain bullet at 3450 FPS, this thing is a screamer!

Here is a link to a good ballistics table:


This is a superior prize, of that there is NO DOUBT!


308 3006 300w 300rum.jpg
308 3006 300w 300rum.jpg15.66 KB
Tndeerhunter's picture
Grand Slam Challenge Winner!
Location: Tennessee
Joined: 04/13/2009
Posts: 1136

The .300 RUM is most certainly an interesting round and concept. By concept I mean how Remington has attempted tp increase it's appeal by offering three different power levels in the ammo they sell for their UM. Power level One has the power of a typical 150gr 30/06 loading. Power level Two has the power of a standard 180gr .300 WM loading. And, of course power level Three is the full tilt boogey .300 RUM power.

This concept should raise it's appeal accordingly as some owners might figure they do not need that powerhouse level three loading for say deer-sized game. Being as how they can purchase a lower level load for this type hunting can appeal to a good number of hunters, especially those that do not handload or don't have the desire to have to experiment and work up reduced power loads for game where high velocity or energy is not really needed.

I read an interesting article a while ago where Craig Boddington was testing the .300 RUM and the three power levels of ammo for it. He actually shot a three shot group with the three different levels (1 round each) and ended up with a three shot group that went MOA. Interesting stuff.

As with pretty much any chambering there might be a down side too. To actually pull all the performance out of that huge case a pretty long barrel is needed and if I'm not mistaken, Remington uses a 26" barrel for this big case. Not a bother to some, but no doubt on the longish side for my tastes. Again, that's just me and surely many hunters do not mind having a 26" barrel on their hunting rifles (repeating rifles). 

bitmasher's picture
Location: Colorado
Joined: 02/27/2002
Posts: 2974
300 Winchester Ultra Mag 

300 Winchester Ultra Mag  Confused

Thought it might be a new cartridge.  Here are some other fun names

300 Winchester Super Short Diminutive Ultra Magnum (WSSDUM)

300 Remington Ultra Compact Super Magnum (RUCSM)

Gotta love the trend of describing cartridges as small (short, compact), but powerful (magnum, ultra magnum).

300 Itty Bitty Super Duper (IBSD)