If you want a magnum you would be better off buying a new one in .300 WSM or the real deal .300 Win Mag.

I just had a .300 Win Mag T3 Lite rebarreled with a Bartlein light Palma, along with an integrated lug and brake. Still developing a load, but got a 4 shot .57 MOA group on steel at 335 yards a couple of weeks ago with 208 A-Max. If you are having a new barrel fitted, you can go for a longer OAL to get the most from the cartridge. Mine is cut for a 3.5″ OAL, which still allows me to extract loaded rounds, but is far too long for the mag, so I am single loading.

Happy to help if you would like some advice.

I will write up a report with pics sometime soon in case anyone else is thinking of something similar.

………… Just thought – you could go with a 7mm Rem Mag with the 180 VLDs too, or even more extreme with a faster twist and the 195 EOL Hybrids.

You may find one with a shot out barrel that you can get cheap, or perhaps get one from an owner who can't cope with the recoil in the Lite configuration. My .300 Win Mag kicked like hell with the Lite barrel. With the Bartlein and a brake it's more like a .30-06 now.

I'm looking forward to seeing what you come up with.

Obviously not on a 30.06 but I bought a 7mm rem mag and re barreled it to 375.300 win mag, easily equals 375 H&H ballistics , good for big critters, I use it on water buffalo, camels and scrub bulls here in Australia 🙂

Best 'magnum' without going to a different bolt face than the .30-06 is probably going to be the .280 Ackley Improved.

You're not going to find 'true' magnum performance in the .30-06 bolt face, but it comes the closest that I've been able to find, and uses the incomparable ballistics of the 7mm platform. If you end up getting a barrel with a twist of 1:7.5 of 1:8 you should be able to handle the heaviest of projectiles, including the esteemed Berger 195gr EOL. (Still jealous that I've only got a 1:8.5)

With the .280 AI you can still fire factory .280 Remington from it in a pinch, and can find factory loaded ammo since the cartridge was standardized by Nosler.

If you're really feeling the need to go to a true 'magnum', you're going to need a different bolt face.

Good advice. The .284 Win offers almost identical performance as the .280 AI and is well suited to a T3 action with the long action bolt stop. You will be able to load 180 VLDs as far out as you like without having mag length issues. Either chambering would be good, and I'm going with one of the two when my 25-06 barrel is shot.

I had my 30-06 rebored to a 35 whelen. 

the 30.06 bolt face will also work with the 6.5×55; you could chamber a 6.5×55 AI barrel and have close to the performance of the 6.5-284

Why 6.5 for elk when 7mm or .30 cal would be far more suitable? Let's offer advice based on the application, not what our favorite chambering happens to be. Straight .284, .270, .280, .308 or .30-06 would all do fine, don't need fire forming and barrels last more than 1000 rounds that a 6.5-284 would.

Keep in mind J that you can purchase .280 Ackley brass from Nosler, now that it's standardized. They also sell loaded ammunition.

The .284 Win is also a winner when you consider that it's fairly easy to get components, and it's not as difficult to load longer bullets since it's a shorter fatter alternative. I've also never understood why 6.5mm is more popular than the 7mm when the 7's have better ballistics.

Fair point on the Nosler cases. I use Nosler Custom cases for my .25-06 and like them. That rifle will become a .280 AI or a .284 when it needs a new barrel. From what I hear .280 loads for fire forming to AI shoot pretty well for hunting purposes. Have you tried that?

I have tried that. My fireform loads group quite well and spit a 139 Hornady Interlock on average 2870 fps. It doesn't compare to what I'm getting with full up AI loads of 180 Berger Hybrid Targets and around 3000 fps. I haven't tested enough to see what works best, and am still waiting for the long action DBM to be able to load a longer COAL.

I don't know how typical similar results would be for someone else, my barrel's 32″ and not the easiest to unlimber in the field. Sitting down or prone though… Just about anything you see, you own.

Asgen,

I see that MT are now offering replacement DBM for the factory plastic piece. They mention that LA, AI compatible version will follow. We may yet get to complete our respective .280 AI and .300 Win Mag builds?