Need Help Choosing Magnum Caliber

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TA0502

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Alright, so I’m biting the bullet so to speak tomorrow and buying a magnum RPR, I just need to decide between a 300wm or 338lm. I already have the reloading supplies for 300wm but this will be the precision rifle I stick with for the foreseeable future for long range shooting so I don’t want to get the 300wm and feel like I chose the wrong cartridge later on. Either caliber I’ll be reloading for and honestly not shooting a ton so ammo cost isn’t a huge issue for me, I usually blow through a bunch of 5.56 and .22lr to scratch my shooting itch when I get to the range then only shoot a few rounds through my large caliber stuff.

I was told that 300wm is a bigger pain to reload precision rounds for as well because it’s a belted round, any truth to that? I’ve also read that the 338lm is a cartridge a lot of new people get in to for the “mines bigger” factor but ultimately get sold or traded off. I built my last precision rig in 308, I ended up regretting it a few months later and wishing I’d went with the 6.5cm so I just don’t want to make that mistake again. I listed up 3 of my rifles for sale to fund this endeavour so any input would be helpful, thanks.
 
What is the intended use of the rifle? ELR? Hunting? How far do you want to shoot?

Hard to recommend a cartridge if we don't even know what the rifle is being used for.
 
If you are going to beat up your wallet you may as well "go big or go home"...I'd love a 338 Lapua, but I could never justify the cost, other reasons as well, any Magnum for that matter.

As for the 300 WM, I had no problems reloading for it. I was getting really nice results with Retumbo, 208 A-Max, and a 30" barrel. That was really pushing things though, right on the edge. The only problem I ran into (other than being right on the edge) was Copper fouling, peculiar to the bullet I think.
 
I'm going to be using the rifle just for long range target shooting. When I built my 308 I was very concerned with ammo cost & barrel life and that's what made me pick 308 over 6.5. But after I only put about 60 rounds through the rifle all year, i really regretted not going 6.5 because i feel like i put quantity before quality.

Thanks for the input so far.
 
kthomas said:
What are you considering "long range"?
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The range goes out to 2000 yards so my current goal is to at least hit that mark.

I've been reading info on trajectories and BC for each caliber this morning and it looks like the best high BC 300wm will out perform 90% of the 338lm rounds. I didn't realize that these round performed so closely but at the same time the information only reached out to 1000 yards. I could go 1000 yards with a 6.5cm so I'm not sure how useful performance info to 1000 yards really is.
 
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TA0502 said:
The range goes out to 2000 yards so my current goal is to at least hit that mark.

I've been reading info on trajectories and BC for each caliber this morning and it looks like the best high BC 300wm will out perform 90% of the 338lm rounds. I didn't realize that these round performed so closely but at the same time the information only reached out to 1000 yards. I could go 1000 yards with a 6.5cm so I'm not sure how useful performance info to 1000 yards really is.
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Quite a bit of options aren't much different in LR ballistics wrt to drop and drift... impact energy is a whole different discussion and I don't think your targets have fur????

JBM is a great ballistics tool to play around with various options and it will calculate to 3500yds.

Since 2000yds is the goal, crunch these numbers and compare the outcome...

G1 BC of 0.7 at 2600 vs 2900fps.. just set everything the same except change the velocity. Compare the drop and drift each 100yds 1500 to 2000yds.

Also compare the residual velocities. If you can find an answer, will the bullet you want to use go transonic?

I think you will find this excercise very enlightening.

Jerry
 
Since you are thinking "long" term AND "long" range (1800 m), advantage .338 LM. That is, as "long" as you are comfortable with the cost of reloading components. Let us know how it goes.
 
Mad-Dog said:
Since you are thinking "long" term AND "long" range (1800 m), advantage .338 LM. That is, as "long" as you are comfortable with the cost of reloading components. Let us know how it goes.
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A lot better choices than .338LM these days. In order to take advantage of the long high BC .33 bullets in a .338LM, you have to single feed them. The Norma's (.300 and .338) are optimized to send the heavy pills from a magazine.

They do everything a .338LM does, and better.

300 PRC is another great option.
 
serious question for you,
can u start a thread about the 300mwin mag and it’s comparables out to 2000 yards
thinking of a 300winmag due to cost,
might just spin on a barrel to a 700 long action and single load it

Your thoughts on caliber just looking to play for a year or two and mot wishing to breaks the bank by building a 338 wizzes in a new custom action

just looking to play at steel for what is called ERL. extended long range as a beginner

kthomas said:
A lot better choices than .338LM these days. In order to take advantage of the long high BC .33 bullets in a .338LM, you have to single feed them. The Norma's (.300 and .338) are optimized to send the heavy pills from a magazine.

They do everything a .338LM does, and better.

300 PRC is another great option.
Click to expand...
 
If you are doing a max of 2,000 the 300WM with a proper twist barrel and bullet will be plenty.

Wanting to go past that with consistency you'll have to step it up if pushing the limits.

Two animals yes, similar up to a certain distance, yes, but they aren't the same animal.

.223 can get to a mile with the right setup.

Think of these things like golf clubs , you can really push a smaller one to it's limits and make it reach but using a bigger club makes life a lot easier.
 
kthomas said:
A lot better choices than .338LM these days. In order to take advantage of the long high BC .33 bullets in a .338LM, you have to single feed them. The Norma's (.300 and .338) are optimized to send the heavy pills from a magazine.

They do everything a .338LM does, and better.

300 PRC is another great option.
Click to expand...


It's actually the 7mm and 30 cal that are getting too long for magazines, the .338 offerings aren't changing a whole lot , the Sierra and Berger bullets are pretty much the same as old, when you have 7mm knocking on 200gr and .308 in the 230gr area you are definitely getting into very long bullets.

But trying to reach the lands in a long throated barrel will make any chambering a single feed.

As well like others have stated, you get a 300gr projectile moving in the 2800-2900 ft/sec department with B.C.'s in the 8's , you better be bringing your a+ game if you want to stretch it out with them.
 
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Kelly Timoffee said:
It's actually the 7mm and 30 cal that are getting too long for magazines, the .338 offerings aren't changing a whole lot , the Sierra and Berger bullets are pretty much the same as old, when you have 7mm knocking on 200gr and .308 in the 230gr area you are definitely getting into very long bullets.

But trying to reach the lands in a long throated barrel will make any chambering a single feed.

As well like others have stated, you get a 300gr projectile moving in the 2800-2900 ft/sec department with B.C.'s in the 8's , you better be bringing your a+ game if you want to stretch it out with them.
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The .338 LM cartridge was designed around a 240 SMK if I remember correctly. The ~300 grainers won't mag feed if loaded to optimum COAL to get proper powder charge.

No such issues with the Norma's. But yes, other .30 cals would have issues with the heavier pills.
 
kthomas said:
The .338 LM cartridge was designed around a 240 SMK if I remember correctly. The ~300 grainers won't mag feed if loaded to optimum COAL to get proper powder charge.

No such issues with the Norma's. But yes, other .30 cals would have issues with the heavier pills.
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What are the loads/powders you find weak with the 300gr projectiles?

Haven't had a problem yet of not having enough case capacity with H1000 , Retumbo or 7828.
 
Kelly Timoffee said:
What are the loads/powders you find weak with the 300gr projectiles?

Haven't had a problem yet of not having enough case capacity with H1000 , Retumbo or 7828.
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I don't have a .338LM. I just know from others that in order to optimize it with the long high BC projectiles, you end up having to single feed it. Otherwise you may not get the proper COAL to get the bullet where it likes to be in reference to the lands.

The .300NM will also have less recoil than a .338LM, and it's more ballistically efficient (I.E. "flatter). Personally, I see no reason to go with a .338LM with the .300NM available.

https://precisionrifleblog.com/2018/06/06/300-norma-mag-custom-elr-rifle/

http://www.accuracy1stdg.com/content/docs/binder7.pdf

https://gununiversity.com/300-norma-mag-vs-338-lapua-vs-30-nosler/
 
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