Brno ZKK 600 / CZ550 series, ring sizes and pos welding

Just to pre-empt, I'm not planning on welding anywhere near a receiver ring, bolt lugs or any cams! I have no intentions of claiming a Darwin award.

Does anyone know whether the receiver ring on the Magnum length Brno ZKK 602/CZ 550 is the same diameter as on the shorter 600 and 601 actions?

has anyone attempted to cut and weld one of these (or other CZ centrefire) actions? how did it work out?

were you able to re-finish the metal without the weld showing as a different colour? or it taking the bluing or parkerizing in a different manner?

what filler metal did you use?

Many Thanks

PS
does anyone have a section of a Ziess Jena 4x scope that came with these rifles? I've just got one that Bubba has had the back element out of, and he didn't get the rearmost rubber gasket back into place properly.

The price was right... and I have a friend who has an optical clean room and dry nitrogen for reassembling it, once it is properly cleaned.

Not same..... 602 is ~1.430 OD of ring. Smaller actions ~1.340

Bolts same OD, but locking lugs are ~1mm longer on 602, Bolt/action length shorter, on 600 601 of course.

Brownells 3.5% Nickle steel welding rod works, and blues perfectly.. Blending matte finish would be tough.

I have found parkerizing shows welding HAZ color changes... Blued finishes are not as picky.

With dozens of available rifles and actions, welding a valuable magnum action makes no sense.

And with 602's longer lugs and larger receiver ring/magwell, you are not going to turn a standard into a 602...

Best QD CZ scope mounts $$$$ EAW brand German...

Thanks for the info.

I've never actually had my hands on the mag length Brno/CZ action. They're way out of my price range. Would love to have one though.

I've picked up an abused 06 length 600. The 06 length cases are out of fashion here, and tired rifles chambered for them are not good sellers.

If it's throat is still good, it's staying exactly as it is, but if the throat is tired...

I've been itching to play with longer wildcats on the .470 base diameter cases, so it would be getting stretched rather than shortened.

Personal opinion and not to hijack my own thread, I think that from a bolt back thrust, aysymetric receiver ring stretch and barrel hoop stress point of view, the ongoing fashion for short fat cases and short actions is seriously misguided...

I think that from a bolt back thrust, aysymetric receiver ring stretch and barrel hoop stress point of view, the ongoing fashion for short fat cases and short actions is seriously misguided...

That was P O Ackley's opinion also. It wouldn't be so bad if receiver and bolt diameters were increased in proportion.

Have it rebored to 338/06 or 35 If needed. Or rebarrel to .270...

Restocking takes any savings out of welding receiver, Add in guard and mag/follower mods..

Bolt action rifles cover the tables at gun shows here. Far easier and $$$$, to just get what you want, instead of dinking around on a project that will only reduce value of rifle. And end up costing what 2 rifles would.

Wildcats make NO sense.. Dies, extra work forming brass, more powder, less throat life.. All for 100 fps more velocity, lose your ammo in a raft flip, your hunt is done.. No wildcat factory ammo around.. Many cartridges started out as wildcats. But there is just not a lot of gaps between available factory cartridges anymore.

Not a fan of brick shaped cartridges, they feed poorly, and will not chamber if dropped wrong way on that sharp neck.. All for a half inch shorter rifle.....

My 602 was about $300.00 in 84 in Germany.. Not much need for one in Ireland, but an Alaskan Brown bear is getting close.

Wildcats make NO sense.. Dies, extra work forming brass, more powder, less throat life.. All for 100 fps more velocity, lose your ammo in a raft flip, your hunt is done.. No wildcat factory ammo around.. Many cartridges started out as wildcats. But there is just not a lot of gaps between available factory cartridges anymore.

Click to expand...

I think there was a quote from an old P O Ackley, close to the end of his life, when someone asked him about wildcats, his reply was:

"save your money instead."

I'll keep my eyes open for a tired, long action Remmington 700. At least it comes with a mag cut out that is long enough for H&H length cartridges.

I'll still be getting some 9.3x74R empties to play with from a friend who shoots them. to see how well they form and how large actual side clearances are with my chamber.

At half as long again as a .308, they should form to give a capacity of around 75 grains of powder, compared to around 80 grains for a 7mm Rem Mag, but with only approx 60% of the bolt backthrust for equal pressures from the 06' case head. Pretty much what the 1939 7x75mm Vom Hofe Super Express did, and allowing 9 or 10mm of burned throat to be removed, and Gibbs like capacity with a sensible length of neck.

The only pay off with things like that seems to be with high ballistic coefficeint bullets out of very long barrels, otherwise, as you rightly point out, with normal weight bullets out of normal length barrels, there is under 100 feet per second difference between a .280 Rem and a 7mm Rem mag, and about 20 grains more powder burned to get it.

Incidentally, something occurred to me that I want to do the calcs on. the slight push forward of the .280 Rem shoulder - I know it is officially said to be to stop it from chambering in a .270, but is it also to give just enough extra capacity to match the .270 at much more reasonable operating pressures than the .270 uses?

The metalwok has cleaned up far better than I ever dared to anticipate, and a try (striker removed) with a friend's 150gr starting load resulted in the bullet stuck in the throat, so there's plenty of throat left to play with.



got me an unexpected bargain that.\apart from a cleaned up crown is going to be staying very much as it is