The 600 overkill project is coming along nicely. This is the first barreled action. The action is a highly modified CZ550 Magnum. The barrel is a 26 inch long Pac-Nor 3 groove 4140 CM tube. The pictures of the second barrel mounted recoil lug show how closely this was machined before it was hi-force 44 soldered to the barrel. These barrels were pre-threaded and long chambered at Pac-nor and had to be headspaced against custom headspace guages. The muzzel brake was built by george Vias. All this work was done in my shop this weekend. The stock is curtesy of 470 MBOGO and has been drilled for three Mercury recoil reducers in the butt and about a lb of lead under the barrel channel. The gun is targeted to weigh about 14 lbs when done.-Rob

Rob,

It looks like the project is progressing nicely. Very impressive muzzle break! I had wanted to get in on the deal with you guys, but the money was not there.

Could you post a picture of a 600 OK next to another, easily recognizable, round for comparison? It is hard to imagine a round that big.

Shawn

Nice Rob!

Has everyone gotten their barrels? Mine didn't get here yet.

What's the diameter of that brake!? Is that 2"?

[ 01-21-2003, 10:20: Message edited by: GeorgeInNePa ]

Rob that is totally awesome. When do you think the first firing will be. Make sure you take some video.
470 Mbogo

George- Pac-Nor shipped your barrel last week. It should be there any day. I have a list from them of people to who they shipped barrels.. If not call them immediately. Yes the brake measures 2 inches. It's a 7/8X24tpi thread 1 inch long.
470MBOGO- We unfortunately have to wait for the brass! It will probably get fired in late Feb/March. I'm working on your stock as we speak.-Rob

[ 01-21-2003, 10:42: Message edited by: Robgunbuilder ]

Rob,
Cool, now I have to come up with money for an action. Is John still making the turned brass?

Beautify work, Rob. I don't care what AXEL says.

Looks awsome Rob, I really want one now !!

Thanks for the the update, Rob.
This Hi-Force 44 ... a prefluxed silver solder? Is it a "Eutectic" offering?

AWESOME Rob...
Can't wait to see it blued and stocked... and then the video...

jeffe

Rob, that is very rapid progress.

Keep blazing the trail for us!

Thats serious artillery. Looking good Rob.

Rob, most impressive! It appears that you are utilizing a stock magazine box, is this indeed the case? It also looks like the arrangement provides a near single stack, is this also the case?

What modifications were required to the action, besides the obvious clearance cut into the rear bridge?

I read your essay at AHR. Very interesting. Unfortunately, $1250 is too much for me currently and I don't have the proper equipment handy to do it myself. If however, in the future I decide to pursue this chambering, how would I get brass, dies, and head spacing gages?

Axel

Rob,

Does Pac Nor have their own chamber reamer, for those of us that didn't have the coin to get in on the barrel deal, but would like to build one down the road?

Looks awesome, and I can't wait to see the project progress.

Paul H- No Pac-Nor doesn't own a chamber reamer or headspace guages. I had the only one made, at my expense. I'm in the process of considering registering this cartridge with SAAMI so as not to lose the proprietary nature of this and to document it's lineage. I will probably not send the reamer out again, but will ream chambers for those who want a 600 Overkill myself. I may also set this service up with AHR in the future. I've informed PPG and JGS not to give out the specs unless they get my approval first.
The action has been extensively reworked for this cartridge. It's worth the $1250 price believe me!The obvious stuff is just that obvious. The more complicated part lies in the magazine dimensions, rail and ramp work needed to get this thing to feed. It will hold two down and one in the snout.
Brass is being made for the original group as we speak and I'm sure Horneber will make more since he now has the tooling. The first test firing should be in a month or so! I'm gonna go very slowly and work up the loads carefully-Rob

Rob,

As much as I'm interested in the 600, I won't be in the market for one for a couple of years. I did finally get confirmation I'll be recieving my 500 Jeffrey barrelled action in the near future, after a long wait. That still leaves me with making a magazine, getting it to feed, and fashioning a stock from a blank, which I figure at my pace is a few years work.

BTW, what do you tap your auxiliary recoil lug? I'm planning on tapping mine 1/4-28, and bedding the barrel from lug to lug, then free floating the rest of the fore end.

Rob,
Looks very menacing. I just sent my barrel to Ed, so hopefully I will have it back in a couple months.
-Is that one of John's lathe-turned bullets?

Paul h- I just tap mine for a 6-48 socket head screw. It's No. 31 drill and countersinked. I drill the barrel only .075 and there is only a few threads worth of engagement.. The single screw just holds the lug in place while it's Hi-Force 44 soldered in place. The solder flows under the lug and wicks into place and flows into the screw hole. This way there is no slippage while soldering. The Hi force 44 solder needs a flux and is resistant to blueing bath chemicals. It melts well below 500 degrees but is quite strong! You do need an air/acetylene torch to get it to flow properly though.
300H&H- Yes that's one of John's Go- Gages in the chamber. The action will actually FEED one of them nearly perfectly! Amazing-Rob

Rob,don't understand the tech stuff, but that barrel looks like it belongs on a recoiless rifle

Some important observations to pass on. This cartridge is humongous. It barely feeds through the primary torque ring. The cartridge must be crimped solidly on a 900 gr woodleigh to feed smoothly. When this is done , it feeds like it's on ball bearings. No crimp. no feed. It looks like CH4D's dies will crimp nearly perfectly. Dave and I got the dimensions nearly perfect-first try.
The magazine is nearly a single stack by default. two down, 1 up is the best you can do without those stupid coffin mags. -Rob

[ 01-22-2003, 08:18: Message edited by: Robgunbuilder ]

I cant wait to hear how the test firing was, and then the MAX loads

Rob, it sounds as though you may need to keep a
watchful eye on the crimps of the rounds in the magazine at firing. Two shots and the mouth of the lower cartridge may want to ride up out of the cannelure. Just thinkin' out loud.

After two shots, I'm not sure who will be hurting more, the shooter or the buffalo. -Rob

Pretty impressive, Shot once,dropped once,sold rifle . Probably going to split the stock into a million pecies,the muzzle break where did that come from,a feild artillery piece? Hope you dont plan on packing this around,at 14 lbs(why bother with mercury recoil reducers?) you will be to tired to shoot it,that is if you can with stand the recoil!

Rob,
I think the actual shots on buffalo will go quite well .... it's the load development and practice sessions that worry me!

My personal goal is to be able to handle 900 grains at 2000 fps. I am thinking of 13 pounds with a brake.

Trust me, the stock won't split under recoil!!! I kinda know what I'm doing here and after carrying a M60 around Vietnam for a short period of my life,(albeit awhile ago), 14lbs is not a problem for anyone in good shape. They will also have willing gunbearers where this gun is going -Rob

I never meant to imply that you do not know what your doing. You seem very willing to put your two cents in on everything in this forum! Just giving out my thoughts as well! It is a cool idea but the muzzle break is way to big!

My barrel got here yesterday! It does look like a shotgun barrel. In fact, it's kind of funny. You expect it to weigh more when you pick it up. DAMN big hole!

Looks good RGB - keep us posted on the progress of this monster - Diesel Dude, keep us posted on your 577 also - this should be an interesting spring / summer shooting season

DAMN! I thought my 500 A Square was big, boy was I wrong! What is the quarry for that thing, Mack trucks?

Looks great.

Lucs

Diesel-Dude- That brake was built that way for a reason. It may be big, you may not like it's looks, but there is no doubt in the world that it works. It's already been on something much bigger than the 600 OK and proven that point unequivocably. George Vias and I spent alot of time on it. From the pictures you can't see what is built in. When your dealing with something that can dish out a level of recoil that is physically dangerous (i.e. over 200 ft-lbs), every known method of recoil reduction is perfectly acceptable in my book. That includes stock design,recoil reducers,pads and weight. This gun has only one purpose to prove the 600OK is a viable big game cartridge and I'm gonna do just that!-Rob

Rob, DD..
I think this is a misunderstanding... I think DD was being humorous, and Rob wasn't, which is why this looks like a "rub" but really isnt.

I might be out of my mind here, but I think DD was giving a back handed compliment. AND joking that lots of big bores a S1,D1,S1, as we've all said.

just trying to prevent a war that might just be a misunderstanding...

you may now return to your regularly scheduled jeffe-message

jeffe

So than that is the "infamous" brake that I heard about. Would you mind telling us what the barrel length was on the "other" barrel that it was on? How would you describe the recoil with that brake.

FWIW- I estimate the recoil reduction of this brake to be about 35-40%. It is not as effective as a clamshell, but it will in and of itself convert the nearly unshootable to a "experience". I have some photo's taken of this firing at night and there is some measure of the gasses being directed backwards for some pull effect. I believe my personal recoil limit to be about 150ft-lbs, based on alot of experience. That's about where this will probably wind up with a 900 gr bullet at 2400+ fps. That's the goal. I'm certain that if the loads are kept to the 1800-2000fps level, lesser efforts to control recoil might be effective. We will soon find out!-Rob

Rob,

What would a 1200 gr cast bullet @ 1800 fps calc out as far as recoil?

Rob

I am glad it is you shooting it and not me.

Please have some one video tape you at the range and when you actually shoot a live creature with it. I want to see what happens to a buffalo when you thump it with that monster.

Is the wood going to be as nice as the rest of the gun?

Jim

At 1900 fps with a 1200 gr bullet. Quickload says free recoiling mass is 181 ft-lbs in a 14lb rifle. Now you can start to see why a brake which gives a 40% recoil reduction is so critical.-Rob

I am sure the 600 OK will be able to handle anything on this planet,I hope it works out the way you want it! RGB,lighten up a little,have some fun,life is to short to be so serious,remember there is no such thing as too much!

Diesel Dude,

We've had a rash of trolls, well, one troll with multiple looser personalities that has put some members of this board on edge. Thus, I think there is a bit less patience when new members make jokes, especially when it's sometimes hard to tell if it's a joke or not.

RGB,

I think we need a new raffle on the African board, but this one requires the shooter to use the 600 OK