Firstly, has this been done before? And if yes, what kind of support is there? Are dies and load data available?
I doubt I'm the first to think of this, but if it hasn't been tried, is there any benefit from a cartridge like this. The RUM case should have plenty capacity to launch the heavier 35 bullets. Should handily outpace the Whelen.

Yes, it's been done before by Bryce Towsley. He did a big article about it, titled "A Wildman's Wildcat", in the May 2002 issue of American Rifleman.

He did it by necking up the 300 Rem Ultra Mag to .358 and caling it the 358 Ultra Mag Towsley.

With a 200 yard zero, it dropped 6.5" at 300 and about 10" at 350 with a 255 gr Partition.

His MVs ranged from 2965 with a 250 gr Barnes X and 90 grains of Reloader 25 to 3408 with a 180 grain X and 101.5 grains of MRP.

It's called the .358 Ultramag Towsley, invented by one of the American Rifleman writers.

Oops. Little late.

[ 07-31-2003, 07:04: Message edited by: Urodoji ]

GFP
I'm not sure the 338 RUM necked up has ever been done before. Townsley's 300 RUM wildcat will get better velocities, but if you're using heavy bullets, and are trying to stay in a given mag box length, the 338 parent case might make more sense. Most people who build wildcats of this nature though are going to go for the 300 RUM because of its slightly larger case capacity. Either way, you're going to best the 358 STA, and have one hell of a thunderstick. If I were you, I'd go to the 9.3 MM just to have something different We'll call it the 366 micmac.

GFP,
BTW, if you want to live up to your name, I think Pacnor has a wildcat based off the 20MM. Should be good for deer and antelope.

micmac,

My screen name is borne of Hunter S. Thompson's writing. One of his pseudonyms was "Dr. Gonzo" and his Sheriff's election campaign was on the "Freak Power" ticket. That and he's into all manner of firepower.

But I do think it fits me in many ways. I tend to gravitate to the upper end of the power spectrum in whatever I do, from coffee to beer to firearms.

Thanks for all the input so far. It's much appreciated.

Cool, big things that go boom really loud are a lot of fun. I wanted to build a 358 STA for a long time, but settled for a .338 Win Mag(not that close huh?) Anyway, lets just say a 358 RUM would be way cooler on the big things that go boom really loud scale In other words, hell yes you should build it if you've got the inclination. Dies should be no problem, nor should chambering reamers or load data. Let us know how it turns out.

[ 07-31-2003, 10:44: Message edited by: micmac ]

Z-Hat guys have one they call the 358 Ultra Cat.
There are probably others doing the same sort of thing as well.
I'm working the details out on this very thing as we speak. Working name is 9x72mm Artemis.
It's a blown-out case, .53" at the shoulder, and a 35 deg shoulder, .35" neck.
Dieter Horneber has said he'd make some cases without the rebated rim for me, so there goes my only reservation towards this case.
If you can loose your grip on the old wallet you can do most anything you can imagine!
I'm thinking 280gr at around 2800 fps, and am having it throated for the 280gr Swift A-Frame.
The STA may be able to come close to this, but at the cost of much higher pressures.
I imagine this thing - and others like it - will be capable of pushing 2900 fps if the gunner is.

[ 07-31-2003, 11:35: Message edited by: Bwana-be ]

I have a 35/404imp. which would be essentially the same thing.I have the reamer still and dies came from RCBS 20 yr. ago. I have in my notes it drives 275gr. A Square bullets @ 2800 with no pressure signsMark

I have seen load data for the 338 RUM which shows 2800fps with 300 gr bullets. I would think that by opening the bore .02" you'd get at least this velocity with a 300gr in the 358 RUM, and a little better with the 275gr if you're loading you loads on the warm side.

My stepfather and I were talking about this same thing before that article came out. we looked at the balistics for the Ultra Mag cartridges and said that a 35 would work great. That article came out and I read it and gave it to Jerry to read. We both agreed the guy was either being very conservative or did something wrong because the performance he showed was not in line with the rest of the Ultramag line. I think if done properly you should have one heck of a good cartridge there.

Red

I thought this might be an interesting thing to play with. So now that I know, where can I find out more? Any way I can get a look at that May, 02 American Rifleman article? I've tried searching online and didn't get much.

Some sample loads would be really cool. Thanks to everyone for confirming this for me.

Gentlemen -- I shoot two .358 STA's. Both are built on Winchester Model 70 actions, one has a custom Winchester barrel the other a Lilja barrel. I am preparing one or both for Alaska as we speak. My load this year is a 270 grain North Fork that averages 2950 to 3000 fps in the Lilja, the winchester being 50 to 100 fps slower very consistently. I shoot a 280 Swift A-Frame that is approximately the same as the North Fork, yet not as accurate. I have shot Barnes, Kodiak, Nosler Partition bullets with my STA's, with the North Forks coming out on top. My loads are 88 to 92.5 grains of RL-22, depending on the lot and bullet. I can get up to 3200 fps out of the 225 grain North Forks, and up to 3100 fps out of the 250 grain North Forks. Being a grooved shank bullet, the North Fork seats differently, pressures differently, and is amazingly accurate for a tough premium bullet. I thought I would relate my STA experience, to compare to some of your information on the 35 Ultra. I don't have any excess pressure problems with the STA. Good shooting.

[ 08-06-2003, 19:02: Message edited by: phurley ]

just something to consider my smith has a reamer for a 358/378 weatherby. i saw the dummy round. a brake would be mandatory. it is sick. i dont know the comparison between the volume of the rum vs 378 but it knocked the guy off the bench when he decided to fire it with the brake removed on a 8.5# rifle.
dumb ass..
wooofer

Phurley, thanks for the info. Very helpful.
I'm really surprised and happy to see your bullet speeds. Especially with the North Fork. I understood those went a little slower generally. What is the COL difference between those and the A-Frames? My round as I mentioned is being throated for the 280 gr from Swift, and I'm hoping the NF won't be too much shorter (although with these big cases, a couple thousandths doesn't mean the same as it does elsewhere!)
According to my figures, the Norma holds about 86 rains of water to the top, the STA holds about 103 or 104 grains, and my wildcat will hold about 118 or 119. Almost a steady progression. The .358-.378 Weatherby holds about 135gr!
That .358-.378 is pretty much insane. The big Weatherby case is for all intents and purposes a belted Rigby, so you could think of it along the same lines as the new .366 DGR.

Seems to me all of these from the STA up really deserve at least 270gr bullets, Barnes X, North Fork or A-Frames, which going 2800 to 3000 fps will surely stem-to-stern any animal in NA and then some.

I will check the COL tonight and let you know. I questioned my speeds with the chronys, now that I use only an Oehler 35P I feel more confident they are correct. I have found that each day is different, therefore I average several groups to determine the stated speeds, or will add "up to" in the statement. These .358 chamberings mentioned are awesome, no matter what poison you shoot. Good shooting.

PHurley
What's your experience been with RL-22 and lower temps? I've only shot my STA in low 70's to low 80's. Noticed an approx. 40fps average difference in velocity. It was brought to my attention that I may want to try Hodgdon extreme powders for their velocity stability.

Sorry to hijack the thread, just a new reloader trying to learn.

PHurley-

Phurley-

I always look forward to re-reading your posts. You must have typed that data 100 times already. I did catch your expected hunts on another thread. Are the Twins going on all of them???

If you had to do it over again, would this Ultra mag intrest you over the STA?? Seems real easy just to neck up???

As for Bryce's chambering, I didn't read every line of the above and it may have been said already..but. I think his cartridge was called the 358 RUM Dumb (not a typo). I though he used the 338 Ultra case on purpose, as it is a tad shorter.

ScottinPa -- I have shot RL-22 powder in temps as low as 20 below. I do my testing from 95 degrees down to zero at home, in hopes of having a load that will perform in all the temperature ranges I might encounter in the field. I didn't detect any difference in POI on the Bull I killed at the low temperature. --------- Jessee Jaymes -- I look at the efficiency of the cartridge when I first get that glint in my eye for something new. I opted for the .340 Wby some years ago, knowing the larger case capacities of the .338-.378 case available at the time. Yes more speed can be obtained by the larger case, but an additional 50 to 150 fps at the expense of 10 more grains of powder were not my idea of efficiency, nor was the additional recoil wanted. That approach led me to the .358 STA in the first place. I also got an opportunity to get a good buy on Gunsamerica on a Winchester Custom rifle I could not let pass. Immediately after I bought that rifle I found another STA at a steal, that rifle had a "Lilja" custom barrel. The Lilja barrel shoot all bullets 50 to 100 fps faster than the winchester, with the Winchester barrel getting normal STA speeds and the Lilja exceeding them. -------- Back to your question Jessee. I have not seen speeds exceeding my STA's from the larger capacity cases, nor have I seen any that match them. I would never tell anyone to cease looking for more and better and different combos, I just think at this time the STA is hard to beat for it's efficiency and speeds. I do know I don't want to withstand much more recoil at the expense of minimum more speeds. Good shooting.

Jessee Jaymes --- I just noticed your other question about the twins. I don't have twin grandsons, but I do have five for those rascals that we all dream about. They range in age from 16 down to 1. The 14 year old is my only hunter at the present and he is going on an Elk hunt to Colorado with me this year, along with my son. The older grandsons are shooters, the 16 year old being an avid golfer (his dad is a high school golf coach), yet he shoots .5 in groups with two of my rifles. I guess the eye-hand coordination of a good golfer helps in shooting also. The 14 year old just shot an inch group with one of my .340's in preparation of the hunt. Happiness is a grandpa with five grandson's who all will need a rifle all their own when I go to the happy hunting ground, and of course each rifle must be fully tested with proper loads, etc. Good shooting.

Sorry, I meant your "Twin" STA's. How many can you get down in your magazines with the STA??? Anyone know if Remington or others have managed to get three down and have them feed???

My STA is built on a Rem 700 and feeds without a problem. Of course its still cherry and hasn't had a lot of reps except on the range.

From a practical perspective, the 358 RUM is best made by necking 375 RUM brass down...this keeps the neck from getting shorter and everyone is better off with wildcats that have bullets that are too SMALL for the bore headstamped on the parent brass. The 35 cal bullets are not especially long for their weight and they will work great in a 3.6 inch magazine witout encroaching on the ogive of the bullet...this is not true of the 338 cal bullets and the main reason Remington pushed the shoulder back a bit on the 338 RUM.

The 358 RUM will drive a 225 gr partition 3300 fps, no problem, and a 310 Woodleigh 2750 fps, so its a hammer. You can load it down to 35 Whelen or 358 Norma with XMP 5744 and keep very good accuracy, so its quite flexible.

Jesse Jaymes -- I will be taking only one of my STA's to Alaska. The flying in the small planes up there requires a minimum luggage weight, the extra rifle would take up poundage needed for cloths, etc. The flyboys frown on anything not absolutely needed. I always take both to Colorado for Elk, the second for backup. The truck and trailer I take out there have plenty of room. I have been known to take three, one for deer, the other two for Elk. One year all three were hunted with every day because other hunters had rifles that weren't accurate or operable after the first day. They made fun of my three rifles until they had to borrow one. Good shooting.

[ 08-08-2003, 17:26: Message edited by: phurley ]

Bwana-be:

If you start at the tip of a spitzer and work back along the jacket, there is some point where the bullet becomes 100% of bullet diameter. In an effort to maximize long range effectiveness, some bullets have this point moved further toward the base, and you can't seat them as deeply without having the mouth of the case forward of the max diameter point.

Some of the long range, heavy 338 bullets out there would have passed this point in a 338 RUM based on the 300 RUM when held to COL 3.6 inches, so remington pushed the shoulder back. You don't find this type of design in 35 cal bullets, as they are not typically used for extreme long range shooting.