300 RUM vs. 30-338LM

[machineman98]

300 RUM w/250gr. vs. 30-338LM w/250gr.

Is there an advantage in one over the other?
Long range target shooting only.
If these are fairly equal, would the 30-338 AI LM gain me anything?
Bullets would be seated for single shot.

 

[B23]

Off the top of my head, the advantages of the 300 RUM would be if you already have a LA Rem 700 you want to use and since you said you are single feeding it would work fine in a 300RUM build without going to a custom action with the larger super mag .588 bolt face and the RUM has tiny advantage over the straight 300 Lapua. ADG makes great 300RUM brass so I don't see any brass advantage for either.

Personally, I would never do a straight 30-338 Lapua or 30-338 Norma. If I didn't want to fireform and "improve" the Lapua or Norma I would stick with the 300RUM. BUT, if you are ok fireforming and you want to sling the 250's I would head straight to the 30-338 Lapua Improved. Improving the 338 Lapua case has a pretty healthy amount of pick up over the none improved version.

I have one of Kirby Allen's 300AX which is his version of a 30-338 Lapua Improved with 35° shoulder. I'm sure some will gasp but mine is actually built on a chromoly LA Rem 700 and wears a Lilja #6 finished at 28 less brake. Mine was built a number of years ago when the heaviest available bullets were the Berger 230's so mine is a 10tw, not sure I can shoot the 250's. I have a Seekins det mag setup in my build, don't think Seekins makes the one I have anymore, that allows a max OAL of 3.900 and if I recall I'm seating the Berger 230 Hybrid Target 3.850. I'm sending them at 3250fps which is a full load but nowhere near redline. I've pushed those 230's as hard as 3400 testing max pressure but that was definitely redline+. In my gun 3250 w/230's is it's happy place. I will say, it has been one of the easiest to load for and most forgiving rifles I've ever owned.

FWIW, if you're considering a 30-338 Lapua Improved you may want to talk to Defensive Edge Rifles. Shawn builds quite a few 300 Terminators, that's his version of a 30-338 Lapua Improved, and he even has dies and already formed brass available for purchase.

As for case design and which one is inherently more accurate, talking to someone like Alex Wheeler or some of the others on this forum would probably be much more beneficial to you.

 

[machineman98]

Off the top of my head, the advantages of the 300 RUM would be if you already have a LA Rem 700 you want to use and since you said you are single feeding it would work fine in a 300RUM build without going to a custom action with the larger super mag .588 bolt face and the RUM has tiny advantage over the straight 300 Lapua. ADG makes great 300RUM brass so I don't see any brass advantage for either.

Personally, I would never do a straight 30-338 Lapua or 30-338 Norma. If I didn't want to fireform and "improve" the Lapua or Norma I would stick with the 300RUM. BUT, if you are ok fireforming and you want to sling the 250's I would head straight to the 30-338 Lapua Improved. Improving the 338 Lapua case has a pretty healthy amount of pick up over the none improved version.

I have one of Kirby Allen's 300AX which is his version of a 30-338 Lapua Improved with 35° shoulder. I'm sure some will gasp but mine is actually built on a chromoly LA Rem 700 and wears a Lilja #6 finished at 28 less brake. Mine was built a number of years ago when the heaviest available bullets were the Berger 230's so mine is a 10tw, not sure I can shoot the 250's. I have a Seekins det mag setup in my build, don't think Seekins makes the one I have anymore, that allows a max OAL of 3.900 and if I recall I'm seating the Berger 230 Hybrid Target 3.850. I'm sending them at 3250fps which is a full load but nowhere near redline. I've pushed those 230's as hard as 3400 testing max pressure but that was definitely redline+. In my gun 3250 w/230's is it's happy place. I will say, it has been one of the easiest to load for and most forgiving rifles I've ever owned.

FWIW, if you're considering a 30-338 Lapua Improved you may want to talk to Defensive Edge Rifles. Shawn builds quite a few 300 Terminators, that's his version of a 30-338 Lapua Improved, and he even has dies and already formed brass available for purchase.

As for case design and which one is inherently more accurate, talking to someone like Alex Wheeler or some of the others on this forum would probably be much more beneficial to you.

Thanks for the info. I have a 300 RUM shooting 230 A-tips @ 3100. OAL is 4.0 Haven’t tried 250’s yet.
I was thinking of something that might have a little more speed with the 250’s, I’m going custom action. I’ve had a 338LM, I like the cartridge but want to run a 30 cal. Yeah, I’m thinking
30-338LM Improved.
I didn’t think there was much difference in the 2 cartridges, but I was looking for opinions and experience from others.
Thank you for taking the time to respond.

 

[DaveTooley]

I've built several 30-338L 30 degree shoulder in 1K BR rifles. All very accurate but too much case capacity for pure accuracy work. But they are fun to shoot. May still have a die set somewhere. I have a reamer for a 7-338L. That would be a laser though briefly.

 

[David Milisock]

I've built several 30-338L 30 degree shoulder in 1K BR rifles. All very accurate but too much case capacity for pure accuracy work. But they are fun to shoot. May still have a die set somewhere. I have a reamer for a 7-338L. That would be a laser though briefly.

My experiance too, I did the shooting for an armorer many years ago as he experimented with big 30's. By the time you could really tweak the loads the barrel was gone.

 

[Ray123]

I have a 300 RUM and a couple of yrs ago toyed with the idea of improving it ...milled the action, set back tbe bolt stop, so it could feed 4.020" cartridges out of the mag, this was a factory Remington with a 26" barrel. With the long throated 4.00" cartridges with 250 Atips reached 2985 fps in the 26" ...but would not stabilize the bullets in a 10 twist. So I ordered a 30" 8 twist Bartlein barrel...but always wanted to try the 308 in a long fast twist barrel, in a long action ...so I chambered the barrel for 308 as I could always rechamber it for the 300 RUM...right? But I liked the performance and economy of the long action & long barreled 308, which fit 95% of my needs so I haven't went back to the 300 RUM project... but it's still there, just need another new barrel, a reamer, and more importantly, the inspiration to complete the job...just lost interest in Long Range shooting after 30 yrs of it...plus the time and costs...especially today...been there.

 

[effendude]

Ryan Pierce has a long thread on this forum about his 300 Norma Mag Improved. So does Alex Wheeler. I own one of Ryan's rifles and it is incredible. I came from having several 300 RUM rifles and there isn't really much advantage to the NMI over the RUM other than exceptional brass life and maybe a tiny bit more performance. Brass in my RUMs would last 2-4 firings, but I didn't really care, it was a 1/2MOA hunting rifle that I shot 10-20 rounds a year through.

300 Norma Improved

Heres my 300 Norma Improved I built for myself. Figured I needed a personal one to test with since Im building quite a few for customers in the near future. I used a Kelbly Atlas Tactical with a .750 bolt diameter/retail is $1100. I talked to Ian, Ryan and Jim Kelbly and the rest of the...

forum.accurateshooter.com

300 Norma Improved 35 degree

Im starting this thread for load data for those that are using my reamer design. There are a lot of different 300 Norma improved designs out there, do not assume the load data is interchangeable because there are slight case capacity differences. I am finally getting back around to tuning my...

forum.accurateshooter.com

Scott

 

[martyj]

I just had my 300 rum rebarelled to a 1-9 for heavier bullets.
Due to shortage started with 220 smk and they hammered the targets out to 1800 yards and never missed a beat. Nailed the 1800 yard steel 3 times in a row before and did very well.
I often thought I needed something a little fancier or better but its hard to improve on that.