Maximum performance from a .338WM

[Topshot]

I am interested to see what is maximum performance that can be gained out of the .338 win mag cartridge.

Has anyone throated a .338 win mag so that the 300gn Berger pills can be seated out to maximum length, with the base of the shank just about level with the start of the neck. This would maximise powder capacity if used in a single shot format.

Just wondering what velocity would be possible with this type of chamber in a rifle with a 26" to 30" barrel.

I'm not interested in other calibres as I already have a couple of the bigger .338's. Just interested in the maximum performance possible from the boring old .338 win mag.

 

[Long Time Long Ranger]

Best performance for a 338 winchester is the 225 grain D62 Cutting Edge bullet .64 BC at around 2950 fps out of a 25" barrel. Can't get a 300 grain fast enough to outrun it before you reach the max effective range of the cartridge. Recoil negligible in a light rifle also compared to the 300 grainers.

 

[AZShooter]

I long throated a 338 RCM for 300 Sierras and when they showed up switched to the 300 Berger Hybrids. Getting 2575 fps with RL-17 and a 30" barrel. The 338 win mag has approx 17% more case capacity so you should be able to gain 4.3% more velocity. I'd say 2650 fps maybe a bit more with a 30" barrel.

So it won't shoot as flat as lighter bullets, if you have a reliable turret system you can make adjustments. Wind drift and retained energy with that .818 BC Berger hybrid is something. Crunch some numbers and make the decision. I would like to hear your results if you decide to do it.

Her is a pic of the 338 RCM.

 

[Topshot]

AZ,
That is some interesting data. If I can get in excess of 2600fps I would be happy. That would actually make it comparable to some of the short barreled .338 Lapua's that are getting around!

Those rifles with their 24" barrels are beasts to shoot with all the muzzle blast so close to the shooter and only 2650fps to show for it. With the mild .338WM in a 30" tube it would be quite pleasant to shoot and a lot cheaper to shoot than a .338 Lapua.

I have a .338 Edge that is due to have its barrel replaced soon. The existing barrel has a 6" knox so plenty of room to set it back. My plan is to chop off the .338 Edge chamber and set the barrel back chambered in .338WM. The barrel will end up about 27".

 

[Mike 338]

I talked to guys at Berger regarding making a 225 gr. hunting bullet in 338. They have no plans for making that weight as there is no advantage over other bullet calibers offered. I'd like to see them rethink that decision as a 225 gr.'er is much more tolerable to shoot without a brake. I gotta think bullets of that weight would be very popular to hunters. I'm re-barreling a win mag right now (on order).

I've also been curious how a Win Mag would do if set up for long, heavy bullets.

 

[alaska]

I been shooting the 338 WM for many years. I really like RL 19 with 225gr Nosler AB in WW brass with FC215GM primers for 2950 FPS in a 24" rifle. With this load I have taken many Alaskan moose. One of my favorite go to rifles along with the 338-06.

 

[Lefty7mmstw]

I been shooting the 338 WM for many years. I really like RL 19 with 225gr Nosler AB in WW brass with FC215GM primers for 2950 FPS in a 24" rifle. With this load I have taken many Alaskan moose. One of my favorite go to rifles along with the 338-06.

I shoot the same load with either the nos ab or hornady sp in a ruger #1 at 2900 fps. I'm at 75 grains of rl 19 here and I use the 215 not the 215m. The only thing I've killed with it is a mule deer at 550 yards. I use my 7mm's and 30's for deer and have this one to have it. I will use it on bigger stuff when my budget allows.

 

[martyj]

I was shooting Nosler partition 210 grn at 3042. It would hold 1MOA but case life was short.