Had a fun day playing with the .600Ok and some new 730gr monometal( brass) bullets I designed and made. I fired them for the first time this weekend and was amazed at the accuracy of these loads and basic lack of recoil. They also fed great. With 179 gr of IMR7828 it was fun to shoot at 2200fps. Today I got serious and started with H414, my trusty drop tube and a working Oehler chrono. I started at 175 gr and finally broke 2700fps with a load of 186gr. The powder is so compressed it will only fit in once fired cases. Recoil was HORRIFIC and exceeds my capactity to deal with it for more than two shots. Quick load says 65KPSI and 12,000 ft-lbs. Cases poped out fine and no sticky bolt lift. Reloaded one case twice and the primer pocket still feels tight.
Pretty impressive performance from a CZ550 based gun.-Rob

You don't own a camera Rob?!?!?

Let's see some of those bullets you're talkin' about!!

The one on the left is the 730gr FN and the one on the right is a 900gr RN made using Fritz454's g-code.

Er? Uh? I can't see anything Rob!

Ok now I see them. So what is that material ..... Lead? Or is your color balance all screwed up on the camera?

Sorry- you caught me fooling with the picture size.-Rob

Those will be sure to get the attention of its prey.

Curious about the design of the tip of the flat nose truncated cone... is that a supercavitation disc?

quote:

Originally posted by Robgunbuilder:
The one on the left is the 730gr FN and the one on the right is a 900gr RN made using Fritz454's g-code.

Rob,
If I get those before I head Upstate, I think that old washing machine drum will have met it's match and experience a through and through piercing
Nasty looking buggers!

Boomstick- Good eyes ( if you blow up the picture you see it more clearly)and you have given away my secret! So far penetration into OAK media has been super but I have not tested it enough nor have I refined exactly how to shape the disc integral to the bullet. To be different I am experimenting with programming the tool to produce a supercavitation disc into the front of all my bullets and still be able to feed.I have a new program written to produce a small radius cup into the supercavitation disc to help stabilize the water vapor bubble. That and the simple driven band design( from the civil war rifled cannon) will be my entre into bullet design. The truncated nose seemed the best way to accomplish this. That and gaining max powder capacity were the objectives of this experiment. In the next run its shape will be more dramatic and evident. Remember, I'm just a poor biochemist playing with programing and CNC tooling for the first time.
BTW- As some of my friends have pointed out beats the T-rex with 750gr bullets by over 100fps at only 55KPSI.-Rob

quote:

Originally posted by Robgunbuilder:
Had a fun day playing with the .600Ok and some new 730gr monometal( brass) bullets I designed and made. I fired them for the first time this weekend and was amazed at the accuracy of these loads and basic lack of recoil. They also fed great. With 179 gr of IMR7828 it was fun to shoot at 2200fps. Today I got serious and started with H414, my trusty drop tube and a working Oehler chrono. I started at 175 gr and finally broke 2700fps with a load of 186gr. The powder is so compressed it will only fit in once fired cases. Recoil was HORRIFIC and exceeds my capactity to deal with it for more than two shots. Quick load says 65KPSI and 12,000 ft-lbs. Cases poped out fine and no sticky bolt lift. Reloaded one case twice and the primer pocket still feels tight.
Pretty impressive performance from a CZ550 based gun.-Rob

Mother-of-Mary Rob. That is a nice looking bullet. What do you think of maybe a case full of H-4350 or IMR-4320 for around 2400-2500 and a little more tolerable recoil??

quote:

BTW- As some of my friends have pointed out beats the T-rex with 750gr bullets by over 100fps at only 55KPSI.-Rob

Rob,

What BBL length were you using...

Not sure if I could match that out of my 20" BBL...

My CZ550 has the 26 inch 3 groove barrel. If you guys have the later 6 groove barrels I caution you to work up slowly and carefully watching for pressure signs. Start at 170 grs of H414 and go up carefully. I'd think you'd lose 150fps with a 20 inch barrel maybe more. H4350 or H4320 should easily hit 2500fps or more at the same pressures. They are not as efficient in this caliber as H414 but they will work just fine. VV540, H4350 and H4320 and WW748 will all work just fine.
BTW- I fired the gun at twilight and had little muzzel flash so its a pretty efficient load-Rob

Ultimate handloading requires CNC at home.

Highjack:

Reckon I need to get some biotech patents producing some royalties and then I can get some CNC installed in a log cabin with a 220V line and make some of these for myself ... copper of course for these expanders:

Saeed has said he doesn't mind a variation on the Walterhog theme. Maybe the bands could be spaced farther apart so the terminal band was right at the start of the boat tail, creating a rebated boat tail effect:



And Andre' said a .395 OCCUP similar to his 500 Jeffery was O.K.:



Now back to the 600OK.