338-300

[muleyman]

I've done lots of reloading, however no experience with wildcatting or new cartridge development. What if any advantage would a person get if they necked up a 300 Win Mag to 338. With a little more case capacity then the 338 Win would there be a big enough jump in velocity to make it worth while or is it the same as the 338 RUM. I don't want something as big as an EDGE, but something for a little more poop with the 225 type grain bullets.

 

[davewilson]

300 win mag is a cartridge that has very good brass.

 

[jwp475]

The 300 Win necked up would gain very little in capacity over the standard 338 Win. The next step up is the 340 Wea and then the 338 RUM in factory loaded guise

Hogdon list the 338 Win at 2792 FPS with 74.5 grains of H-4831
Hogdon list the 340 Wea at 2889 FPS with 86 grains of H-4831
Hogdon list the 338 RUM at 2977 FPS with 93.5 grains of H-4831

The 338 RUM breaks 3055 FPS with 103 grains of Retumbo with the 225 grian bullet in a 24 INch barrel according to Hogdon...

 

[Jumpalot]

I had checked into doing this same thing. But decided if I was going to go through all the necking up and everything, I'd just do an Edge. I didn't figure I'd gain enough over my 300 mag to justify the effort. So, I changed my whole project from a light pack around rifle to a full blown dedicated long range rig.
I don't thik you're going to get anywhere near the performance this route as a RUM.

 

[muleyman]

According to Nosler's web page, they show that 71.5 grains of IMR 4350 has a MV of 2882. It doesn't list a barrel length. Does this seem a little fast or is it correct. I thought about calling them jus to double check......

 

[royinidaho]

Here's what I did.

I started with a 338 Win Mag. Bought it as a donor action. However, once reconfigured stock wise and a brake added she did really well.

Typical velocities:

225 class bullet - 2880 FPS
250 class bullet - 2800 FPS

I posted my velocities and people like GG indicated it was a bomb waiting to blow.

Accuracy and consistency was super @ 200 yds but ES was in 30s and couldn't hit for squat beyond 800 yds.

I kept looking longingly at the 300 WinMag case and wondered why it was so much bigger. but I don't like belts ........

I also looked longingly at the 300 SMK but it was too much weight for the Winnie I thought.

So........I scored a 40 buck new take off 338 Rum bbl from Kirby and had it fitted locally (that took only 7 months - a real bummer) Swapped brake also.

Final results with the Rum. 300 SMK @ 2737 +/- 1 FPS. Unspeakable group size @ 200 and enough energy etc. to make a LRH rifle out of a sporter weight rifle 10 LBS 'all up' as they say across the water.

BTW, she wouldn't shoot 225s and 250s to my liking but with 101gr US-869 and GM-215s its a real dream to shoot.

I've noticed that several fellas shoot their Edges down around the 2700 mark though she'll do at least 150 more.

With the proper stock, bipod and scope she's good for consistent hits at the "range" on the 1000 meter gong. In the field we're not quite that far yet.

I use the 270 AM for reaching out and touching things. But for a carry gun that will reach out an do in an elk or bear the sporter weight 338 RUM is a real sweet heart.

The part of me that still dreams is dreamin' of a 338 AM or some such thumper. The time of flight of that cartridge is awe inspiring.