My new .300 RUM


Well-Known Member
Jun 4, 2003
Hermiston, Oregon
Hey everybody. Been a while since I've been around a computer. In the middle of moving into a new house but I did manage to acquire a brand new .300 RUM. I had been debating a long time whether to get that or .338 RUM. I figured I could shoot the .300 RUM w/out a muzzle brake so thats what I decided to get. Also for the ranges I am likely to shoot which is a max of 700 yards on elk and bears, the .300 RUM should still knock em dead. The rifle is a Remington model 700 BDL Laminated/Stainless. I opted for the laminated stock over synthetic to help with recoil. Also, I have more than enough synthetic stocks and there getting dull to look at. I also got another Leupold VX2 6-18 Target with leupold bases and rings. I will take the trigger down to 2.5 lbs and start testing it out tomorrow evening with barrel break in. My deer season starts October 4th and I want to have it ready before then. I'm hoping to get it done in time. I am in a dilema as to which bullet to shoot. I dont want to go any lighter than 180g simply for barrel life and long range shots they have more energy. 200g is what im really looking after. I have some 180g b-tips and also 200g SMK's. They'll all kill deer quite easily, but I'm mainly interested in knowing which bullet would be the best for an elk or bear at 500-700 yards across a canyon. Also what powders and combos have you found to work out in the 300 RUM? I have some H-1000. My goal is to get a good fast, accurate, hard hitting load that will knock down elk and bears off there butts to 700 yards with shoulder shots and hope it will shoot 3 shots into 1 MOA at whatever the distance. Thanks for any help or advice you guys can give me.
Congrats on your new purchase!

I have found that RL 25 and .300RUM's, were made for each other. Using a 180gr. bullet.

The only bullet my Sendero SF wouldn't shoot, was the Nosler BT.
Congratulations remingtonman! I've been shooting the 300RUM for a couple of years now and I love it! For your elk and bear I'd pick up some different bullets....I hear the new Nosler Accubonds are the way to go but I haven't tried them yet.You might want to try looking at the for some loads,they have some excellent ones there.Here's a few of my loads to get you started:
1) 96.0 gr H-1000, Fed 215 primer, 180gr B-tip
2)95.1gr RL-25,Fed 215 primer, 180gr BTSP (3244 fps)
3)95.0 gr RL-25, Fed 215 primer, 180gr Barnes XXX (3389 fps)
4) Promise not to laugh at this one!
82gr RL - 22, WRLM primer, 220 gr Round Nose (2910 fps)
5) 91.5 gr H-1000, Fed 215 primer, 220SMK,(3090 fps)
I have also noticed that my H-1000 loads are with the older version of that powder. The newer H-1000 Extreme seems to be a tad hotter. I subsituted it straight across and found my accuracy dropped off and I gained velocity and the pressure signs that go with it.You should take note of which version your going to use.My rifle by the way is the Sendero SF.I have also started playing with the Retumbo powder. I haven't settled on a load yet but I was getting good groups with 90.5 gr Retumbo,Fed 215 primer, 220 SMK.I feel I could go up a grain or so as my velocity was 2930 fps with no signs of pressure.I'll be trying that in the next few days. Hope something here works for you. Good luck in the hunting season.
I think I am going to buy a pound of RL-25 and some 200g Accubonds. I am usually a RL or Alliant fan of powders just because luck in the past with different calibers was always great, but I wanted to try Hodgons extreme powder for temperature sensitivity. I am hoping to get 3400-3450fps with 180g bullets, and 3200fps with 200g bullets. I heard where a couple guys have gotten 3500fps with a 180g out of there factory 26" with the MAX load for that rifle. I was maybe thinking about buying some 180g Combined Technology Ballistic Silvertips. I have shot many of them through several guns and they all shot more accurate and were a little faster then the regular Nosler B-tips. Maybe I could achieve 3450-3500fps out of it with the rifles MAX load. I would think past 300 yards they would work just fine on elk and bears. One of my friends just got back from a successfull bear hunt and he shot his black bear from 320 yards with a 180g Nosler B-tip out of a .300 WIN that I loaded for him. I used a max load of RL-22 out of the Nosler book. It consistently shot 3/4" and moved along at 3150fps. When he shot that bear, it dropped on the spot and left about a 1.5" exit hole. So many choices to try I guess. When I finally get my load with whatever bullet shoots good, I'll be sure to post it and hopefully have a story to tell about the big muley I'm going to shoot hopefully. Ha ha ha. Thanks a lot guys for the suggestions and advice. Good bunch a guys here.
Hey 25-06....I see you everywhere. Welcome to the world of the 300 Ultra-Mag. I came to the same conclusion as Sakofan. I started out with 7828 when there wasn't much data to be found for this cartridge. I drew blood a few times from the scope hitting me in the head. I developed loads with the Re-25, and not only improved the re-coil, but improved accuracy. Also, I had to do some bullet research, cheap bullets will separate the jacket from the core at these velocities. I ended up with Speer Grand-Slams, they get perfect mushrooms on recovered bullets from Elk. is a good idea to do a little reduced load research with heavy bullets. If you are hunting brush with-in 100 yd shots, bullets have a tendency to just 'zip' through with very little retained energy and knockdown power. Accurate Reloading has some excellent data that is safe in the Ultr-Mag with loads all the way down below 2000 fps.
I loaded up some shells with H-1000 and 200g SMK's tonight. Each with 91g,92.5g, and 94g of powder. I got the info from Velocity is in the 3200fps and accuracy is average of 1/2" with those 3 loads. Of course my gun is different, but I thought since I had the bullets and powder I might as well try them out. I wont get to try them out untill tuesday evening. I'll let ya know how they do.

Your from Hood River huh? We just went over and got our butts kicked in football from you guys on friday night. 28-6 I recall. We really suck this year. Thanks for the recomendation of RL-25. I get paid wednesday so it will be time to buy a couple different powders and bullets. Good to see another long ranger from Oregon.
Forgot to mention a couple things. Can I necksize using a FL die? I thought I read somewhere you can. IF you put the press handle all the way up with the shell holder and screw the sizing die untill it touches the shell holder or something like that? Im not positive, but I would rather neck size than full length size. Right now all I have is the RCBS FL die set. Also the first bullet I seated dented the hell out of the shoulder right up near the neck of the case and it ended up looking like a weatherby double radious shoulder. What the heck happened there? I was seating them to 3.6" which is the OAL for the cartridge. Maybe I need some tips for loading this cartridge. Its a new cartridge to me and have heard that some people have had trouble with the RUMS. I hope I dont have any serious problems, but I ran across those tonight while loading up a couple test rounds. Any information why or what caused this is more then greatly appreciated.

I'm shooting 90gr Retumbo under the 200gr Accubond and all I can say is that it shoots great in this sporter I have.

Are you sure you didn't get the dent from too much lube when sizing the case? Dented or collapsed? Outside diameter of the neck before seating should be no more than .003" - .004" less than it is after the bullet is seated, for a press fit of that much. .002" is what I use, but My die uses neck bushings, so I do have better control of it than you may. Excessive press fit, lack of a mild champfer is the only thing I can think of that would collaps and round shoulders tho.

My loads OAL is 3.660", as long as the mag box will allow.

After you fire the cases once, you can partial full length resize (P-FLR), but you need a neck sizing die to just size the neck and leave the body alone.

To P-FLR cases, run the FL die down to the shell holder and back it off a turn or so, enough that when you size a case, the case will not chamber in the rifle. The reason it won't chamber in the rifle now is that the body has been squeezed in and the shoulder has actually moved forward as the brass worked forward. The die is too far up to make contact with the shoulder when it's sized, at this point this is what you want. Now that the case is too long to the shoulder at the datum line, adjust the die down 1/16th turn at a time until the case just chambers in the rifle with not too much effort on the bolt. Remember to lube the case each time you run it back in with the die a little lower or
. What you want, and are trying to achieve, is a case that is forced against the shoulder and the boltface with zero headspace and is thus centered up in the bore perfectly, just allowing you to close the bolt.

You can monitor the headspace length with a Stoney Point tool or just use an empty 44 Mag case slipped over the shoulder to measure it. The length to the shoulder on your once fired cases will probably be a little shorter than the number your looking for (a thou or two).

What you're trying to do is to keep the cartridge from laying on the botttom of the chamber by forcing it up tight against the shoulder which will center it up, this way there is clearance between the neck and the chamber all the way around, and the bullet is thus centered to enter the bore perfectly when fired.

Properly set up this way, headspace will always be the same from one loading to the next, not getting tight after a couple as it will with only neck sizing, thus requiring a run through the FL die, which will possibly change the way it shoots when you do.

If case neck runout becomes a problem, and it easily can if you neck size, P-FLR or FL sizing will eliminate it or almost completely do so, neck sizing will not, and can multiply it as well.

Good luck this season.

[ 09-29-2003: Message edited by: Brent ]

It was not caused by to much lube. The whole top of shoulder right below the neck was collapsed and totally transformed. It looked like a Weatherby design of the double radius.

My rounds are loaded to 3.6" which is shorter than yours of 3.660" and about 6 of my shells are pretty hard to get the bolt to shut, although when I resized the cases, before putting powder and bullets, there was no problem getting the bolt to close. The bullets aren't anywhere close to the lands.

I tried the Partial Full Length Resizing on a couple caes and I think I'll probly stick with that. It sounds better than neck sizing, and I wouldn't have to buy another die.

Would the set up I have be good to hit a 27" tv screen at 1000 yards? There is a local competition every year and this year I want to enter. My scope is a Leupold VX2, 6-18 Target with Leupold bases/rings. I am more than likely going to use the 200g SMK.
Since I just got a 700 LSS in .338 RUM, and I've been going through the process breaking of it in and working up loads, I can share a few observations:

1. Your cases might be getting squashed because there is no chamfer in the factory cases. Take your little tool and chamfer the inside of the mouth just a tad. My factory cases were nice, but still had a few questions when loading them up for the first time. Once I started chamfering the mouths, which is normally not a big concern, the force to seat the bullet dropped in half. It was an unusual occurance.

2. My factory barrel was ROUGH! I had 160 rounds down the barrel and it was still fouling really bad and the accuracy wasn't all that great. That was after pillar bedding the laminated stock, floating the barrel, and adjusting the trigger to 3 pounds, AND installing a Vais brake and re-crowning the muzzle. My 'smith scoped the bore and the last half of the barrel was STILL very rough. I talked to a guy that had a .300 RUM that had the same problems. Very rough bore and poor accuracy. He had his barrel lapped and it solved the problem. I ended up fire lapping my barrel using Tubbs Final Finish. Check it out, it works well. Now it's shooting well.

3. The factory crown was BAD! The factory tool chattered on the crown. Not a pretty sight. Check it over closely.

I'm now getting a 9/16" pattern, which is a ragged hole with this using 250 grain GameKings and 83.2 grains of IMR4831 scooting along at 2859 fps. I got up to 3004 fps, but the accuracy wasn't there.

The loading charts are very conservative. I ran out of space using WC872. 104 grains is a compressed load, and is about the same speed as H870 or H1000. I've put up to 93 grains of WC852 (mil-surp 4831) and got 3077 fps. So far no visible pressure signs. Your .300 may like slower powders more, but don't be afraid to give 4831 a try.

4. Plan on bringing a towel soaked in ice water to the range to cool the barrel. I can get off about 20 rounds an hour and keep the barrel cool enough to hold with my hand. Shoot 5 shots, wrap in cold towel, clean barrel if needed. When cooled, shoot 5 shots and cool it down again.

5. Recoil will be about double that of a 7 mag. Plan on it. Take the appropriate precautions. A 10 pound bag of lead shot I've heard does wonders. My brake works well for me.

Have fun and burn LOTS of powder!

Mark in Utah
25-06 you are probably over crimping the case!!! The RCBS seater dies are meant to have a crimp feature which if you mean to do it has to be set up properly. If you do not want to crimp all you have to do is back the die out of the press slightly and adjust the seater stem down with the screw. If you are trying to crimp with this type die your trim heights and chamfers all have to be perfect!!! If you must crimp I would suggest seating your rounds with the die and getting a Lee Factory crimp die for crimping!!! Personally I do not crimp my ultra rounds.
Good luck!!!
25-06 PS I use the same load of reloder 25 at 95 grains and 178gr Amax. I get 3300 out of the 26" barrel. I wouldn't even try to get 3500 as you suggested before because it will be way high on pressure!!!
I bought a box of the factory 180g Nosler Partitions to shoot for breaking in the barrel and to get me started with 20 pieces of brass. I shot and cleaned after every shot for 10 shots, then shot 3 shots and cleaned till I was out of shells. 3 shot groups were a little over an inch with a flyer because of cleaning. On all my groups, the 1st shot was always a flyer but the 2nd and 3rd were 1/2" groups. They chronied an average of 3245fps 15 feet from the muzzle with no more than 30fps being the maximum deviation in velocity, and on a 80 degree day. I then shot 3 shots at 300 yards with the 180g Nosler partitions and it measured just over 2 inches. Next I tried my reloads of H-1000 and 200g SMK's. I loaded up 3 different loads or 9 shells altogether. 91g, 92.5g, and 94g of H-1000 seated to 3.6" They all gave me 1/2" 2 shot groups with the 1st shot on all of them being a flyer due to cleaning the barrel I suppose. I chronied the 94g load right at 3200fps. Maximum deviation was 25fps. I will try them next at 300 yards then sight in dead on at 100 and get my ballistic charts ready at least out to 600 yards on Friday and shoot a couple at milk jugs at 500 and 600 yards to test out how close they are and make any final adjustments. My deer season starts Saturday so I will be hopefully done just in time. I'll keep all posted on how everything goes.

PS. I got the small problems fixed. Thanks for all the helpfull advice.

Good to see you get that rifle! I was wondering what happened to you. Last we heard, you were thinking of getting a 300 Win Mag heavy barrel but opted for a Remington 243 ADL synthetic, I think. Anyhow, I'm glad you were able to get a big game gun for Long Range. I have been testing my 7 RUM and found, so far, that it likes H-1000 too. As for neck sizing, I wouldn't worry about it too much. The latest Sierra Manual said that "contrary to popular belief most bench rest shooters don't strictly neck size but full length size" I have always FL resized and haven't had any problems. However, I am new to shooting 700 + yards too with rifles (well hunting rifles anyway, Uncle Sam let me fire all sorts of **** much further than 700 yards!) So, unless I can't get the accuracy I want from FL sizing, I'm not going to worry about buying the dies. Being new to this LR stuff, there's a learning curve which we're going to have to go through. Anyhow, keep us posted. Those 700 BDL laminates really look sharp!

Good luck!
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