thesheepdog
New member
Hi guys!
Well I have been working on something special for the past few months that I thought might interest you:
I was in need of a magnum cartridge that could go well my beyond what I do with my 308 at 1200 yards.
So I began the seemingly endless journey of selecting a caliber to the job.
Long story short I wanted a .338 bore so I selected the .338 Edge....but that's not the "special" project I was referring too.
I also had a barrel chambered in 338-300 (338/300?) Win Mag.
So what is this? It's simply just a 300 Win Mag necked up to 338. My favorite reamer company actually makes very nice reamers for the caliber with long throats and such.
So what does a 338-300 Win Mag do that a 300 Win or 338 Edge won't do? The short answer is "nothing really!". I wanted it merely for redundancy as RUM brass isn't very readily available. Essentially, all I have to do is neck up some 300 Win Mag brass and boom! I am shooting all day long!
I had no load data for this cartridge to start with, but after measuring similar cases and their H2O case capacities, I started developing my own loads.
After spending multiple hours slowly incrementing loads with different powders, I ended the with the following results:
285 AMAX
28" Bartlein MTU
80gr Retumbo
3.785 OAL CIP mag length
Rem Mag Primers
LC brass
2773 fps
2768 fps
2770 fps
No bolt lift or flat primers. YMMV
Second load:
Same specs but as the above load except a different powder-RL19
2731 fps
2740 fps
2735 fps
I have yet to work on some other loads with the target load being a 300gr Berger RL33. I plan to test this powder/bullet combo in the next few weeks. I expect to be able to hit the 2800 fps range as I have quite a bit more throat room in my chamber from the 338-300 match reamer. Currently I am loading all bullets to AICS CIP Mag Length
If these loads seem impossible to any of you, just for some perspective, I am shooting 208 AMAX out of my 308, 24" barrel at 2600 fps with RL17.
Anyway, here are some pics.
Well I have been working on something special for the past few months that I thought might interest you:
I was in need of a magnum cartridge that could go well my beyond what I do with my 308 at 1200 yards.
So I began the seemingly endless journey of selecting a caliber to the job.
Long story short I wanted a .338 bore so I selected the .338 Edge....but that's not the "special" project I was referring too.
I also had a barrel chambered in 338-300 (338/300?) Win Mag.
So what is this? It's simply just a 300 Win Mag necked up to 338. My favorite reamer company actually makes very nice reamers for the caliber with long throats and such.
So what does a 338-300 Win Mag do that a 300 Win or 338 Edge won't do? The short answer is "nothing really!". I wanted it merely for redundancy as RUM brass isn't very readily available. Essentially, all I have to do is neck up some 300 Win Mag brass and boom! I am shooting all day long!
I had no load data for this cartridge to start with, but after measuring similar cases and their H2O case capacities, I started developing my own loads.
After spending multiple hours slowly incrementing loads with different powders, I ended the with the following results:
285 AMAX
28" Bartlein MTU
80gr Retumbo
3.785 OAL CIP mag length
Rem Mag Primers
LC brass
2773 fps
2768 fps
2770 fps
No bolt lift or flat primers. YMMV
Second load:
Same specs but as the above load except a different powder-RL19
2731 fps
2740 fps
2735 fps
I have yet to work on some other loads with the target load being a 300gr Berger RL33. I plan to test this powder/bullet combo in the next few weeks. I expect to be able to hit the 2800 fps range as I have quite a bit more throat room in my chamber from the 338-300 match reamer. Currently I am loading all bullets to AICS CIP Mag Length
If these loads seem impossible to any of you, just for some perspective, I am shooting 208 AMAX out of my 308, 24" barrel at 2600 fps with RL17.
Anyway, here are some pics.
