A recent experiment with necked down .600OK brass shows great promise. I chambered a .375 barrel for the .375/.600OK and simply screwed it on my test action a CZ550. The cartridges actually fit in the mag box and fed! 300 gr brass FN solid( Bridger) hit 3950fps and went lenghthwise through 7 ft of solid OAK logs into the dirt backstop! Thats penetration! Even the 12ga FH won't do that. With better powder selection I think 4000-4100 should be doable. I fired some ten rounds and could still see some rifling was left in the barrel. Load was under 65Kpsi and recoil was stout. Of course at these pressures a muzzel brake made a considerable difference. I wonder just how many of these rounds a barrel can take? Twist? fast becoming a smoothbore! I'd be happy with 500 or so, just like a .30-378 which this round resembles. Buffalo beware! -Rob

Good to hear Rob. A couple years ago I bored out chambers based on the 600 OK in 375, 416, 458, 475, 510, 550 and 585. I've got them fit to a GMA action but have only gotten to test fire a few very light loads. My first impression is that the 510 is the best of the bunch but the 475 is a personal fav. I love the caliber. I thought he 375 would be too much overbore and though of trimming the barrel to use a shorter 600 case. 300 grs @ 4000 fps or so would be a hell of a good long range rifle.

I went with a one caliber neck and a 40° shoulder. What did you use?

As always, nice going.

rob...thanks for doing some background work for pc's 395 nyati!

https://forums.accuratereloading.com/eve/forums/a/tpc/f/4711043/m/199102295/p/1

and without a belt...

Rob,

Sounds like the ultimate long-range buff gun! I’ve read a lot of posts about the CZ 550 bolt (.700) being too small for large case heads and high pressures. What size case head does the .600OK and its long-range counterpart have? Have you had any issues with bolt thrust in the CZ with these large cartridges loaded to these pressures?

Matt V.

p.s. congratulations on a successful wildcat

Rob, how was the accuracy? You may have created the next generation of long range SNIPER round. Get Bridger or North Fork to make up some mono-metal 270gr sptizer, boattails. Could be a 1 mile rifle.

Keith

pics please

Holy spit!! Thats about 11,200 ft lbs of energy at the muzzle! Not to mention the banjo string tradectory. Can you get a hold of some GSC HV's for testing?

Rob has gone where most fear to tread.
Another successful stunt with another impractical wildcat.

Personally, I wouldn't settle for anything less than a full length .395/50BMG.

quote:

The cartridges actually fit in the mag box and fed! 300 gr brass FN solid( Bridger) hit 3950fps and went lenghthwise through 7 ft of solid OAK logs into the dirt backstop! Thats penetration!

Man, you gotta start video taping that shite!!! That would be very cool.

Congrats!

Cheers,
canuck

Fritz 454 and I had this idea at least three years ago and just never got around to it. Yes it has a 40 degree shoulder. I made a half reamer and just cobbled it together for Ha ha's. It's stupidly overbore and barrel life will be proportional to running a plasma torch through the barrel. It will generate some impressive numbers though. I suspect a .395/.585 Nyati will be nearly identically useless but won't have enough powder capacity to breaK 4000FPS WHICH WAS AND IS THE DESIGN GOAL.. Accuracy will be great for 100-200 rds or so then fall off steadily as the bore burns out. Same as a .30-378. I have to rebarrel my .50BMG 1000yrd gun every 1000 rds and I see accuracy drop off after 500 rds. The .700 bolt body with a .600 OK case HEAD is not a problem. Sure there is little rim left but so what. There are at least 10 .600 Ok's running around just like it with no problems.
As for wildcats, its not exactly the first that I've designed and completed.-Rob

By the way,I did once make a .375/.50BMG. Talk about scary. Talk about a plasma torch. I never pushed it over 3700 fps.-Rob

jesus rob... you and spare time and a shop!!!

LOL

keep up the good work!
jeffe

Rob, is this using CM or SS barrels? Would it make any real difference?

Keith

300 gr brass FN solid( Bridger) hit 3950fps

Wow that's just a Thousand fps Faster than my 375 ultra

Hog Killer. SS barrel soon to be very corroded SS. I doubt it matters in .375. Yup given enough powder capacity you can get lots of speed. The 600Ok basically optimizes with case loads of Varget and RL-15.Way more than you'd ever put in a Nyati. The .375 bullet also doesn't rob case capacity like the 900 gr woodleigh does. Shooting this thing is kinda like shifting at the red line.-Rob

Oh My! 300 gr at 4,000 fps. Who said a cannon had to be crew served?

Guess the only question has to be something like "but do we need a 400 yard Buff cartridge?"

Wow! 3950 fps with the .375/600-OK rig is incredible!
My .204 Ruger just shoots about 4150 fps.

What powder did you use?

If you backed off to 3200 fps for a long range hunting load, would it require a filler for the case?

Dak

The .204 Ruger actually gave me the idea for this thing and I was really curious to see what the limit could be. Theoretically, the .375/.50BMG shold well exceed 4300fps, however, after borescoping the barrel I deceided it wasn't worth the effort.
I'd doubt you'd need a filler to hit 3200 or even 3500fps.. I'd think Rl-22 or 25 would deliver those velocities and still fill the .600OK case. -Rob

rob...what about wildcatting the 416 barrett???

700 barrett!

Did it 15 years ago in the .600 and .700 RLG. .50BMG based. The .416 Barrett will also have a very limited barrel life, but given their accuracy level you would never know the difference.-Rob

Rob, I suggest getting a Half Moon barrel, it is my understanding that they are popular with NASA because of their durability. they are so hard that some smiths don't like using them because of the wear and tear on tooling. Probably just the ticket for what you're doing.

Red

Rob,

I wonder wether one of the big BAT actions would hold this round...................what kind of accuracy do you expect to get, also are you willing to list your loads ??

I wonder what one would get with a 235 gr speer ??

Or how about a "short action cart?"

torque...all that cart needs is a rebate

what gun can shoot that?

This is the 50 Fat Mac. That's all I know.
A rebate probably wouldn't hurt.

There are at least 10 short .50BMG varients including a .458 and a .585 that I know of. I personally use a Mcmillan repeater action for my .600 and .700 RLG. I even have one with a .378 wby boltface. With that action I suspect I could get 4200fps with the .375/.600OK. Then there is the OK-2 and OK-3 cases with even more capacity. -Rob