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BRNO ZKK Project

25 Jun 2015
@ 03:14 am (GMT)

Mike Dewey

Hello All, thanks for the opportunity to blather.

I'd wanted a 'thumper' for a while for moose and elk. Thought 35 Whalen, but hard to find. Saw a picture of a CZ 550 full stock in 9.3x62 and was smitten. Only problem: unavailable, discontinued. Dang. Found an ad for a ZKK 600 Brno, cut down 20" barrel, ugly stock in 9.3, thought and then bought.

On arrival, didn't look as bad as in photo, mostly just awkward black spacers added to increase pull length. Took out one spacer, sanded down the recoil pad, lemon oiled the stock and look: nice checkering and tiger stripe walnut popped out. OK.

Bad job of a front sight on the cut down barrel, too tall. Tried to sight in using the sweet pop up peep in the rear scope base but 18" low at 50 yds. Put on a lower front Marbles and back in business just in time to dispatch a problem bear.

BRNO ZKK 600 on the front scope base and 70 524 17,792 on the right side of the action. I figure this means 1970 circa Brno mid length action (in 9.3x62). Not sure whether the 524 means that it's a Brno made by CZ or what. Sounds like there was an unhappy marriage between the two companies in those years.

Lots of time on my hands and spent a lot of it cleaning. Looked fine but every patch, every oily rag came up brown from surface rust. Took a lot to clean out the bore but seems fine now, no pits that I can see.

Was missing the front 'pillar' between the bottom of the recoil lug and the front bottom metal. Couldn't find anything close to the right inside/outside diameter so cut a piece off a useless tripod leg to fit between the lug bottom and the bottom metal. Used shrink tubing around the aluminum tube to fill the space in the stock hole (don't laugh, I'm Canadian).

Put on a Leopold 2-7x33 VXR scope with Leopold CZ 550 rings and started load development. Understand that powder, brass and bullets take some effort to find here. Started with IMR 4320 and managed a 3 shot group under an inch (100 yds.) with 57.5 gr 4320 and Nosler 286 gr partition. Seems hopeful. Got 2267 fps average and 15fps variation with a very compressed load in a new PRVI case.

Since then found some IMR 3031 and IMR 4064 along with some Hornady 250 gr GMX (copper fouls like crazy) and some ugly 285 gr PRVI round nose (but cheap).

Having fun. Once fired cases (I only neck size and did find a custom Lee 'Factory Crimp" die) take at least 2 or 3 gr more powder so will try some heavier loads. Seems the 20" barrel costs at least 200 fps according to published load data. Thinking the 3031 might be the ticket with the shorter barrel.

No signs of excess pressure. Lots of free bore, couldn't touch the rifling if I tried. Will keep playing.

Rifle supposedly came with two triggers: standard and a single set option. Mine has the standard version. 7# out of the box but luckily did have a lot of creep, almost two stage. Took some research but pull is now 36 oz. and took out all the creep by using JB Weld to glue in a piece of tin to take up all the slack. (Remember, I'm Canadian.) Breaks clean and is stable: can't make it fire except with the trigger.

Will bed the action when I quit playing. Wondering about cross bolts, lots of beef behind the recoil lug and behind the magazine box...

Noisy safety (backwards of course but seems natural now: stalk with forefinger on trigger guard, thumb on safety. Ready to fire: just pull back thumb, as you would anyway, and good to go). Noisy, big click. The bear heard the click and turned towards me just as I fired. Diagonally through neck and out shoulder. No contest.

The adventure continues...


25 Jun 2015
@ 10:26 pm (GMT)

Nathan Foster

Re: BRNO ZKK Project
Nice write up Mike, thanks for sharing.

Yes, she'll handle a relatively fast powder but there is no need to go too fast. 3031 sounds good but I would also want to play with 4895 burn rate and keep filling her up (remember you're Canadian) and see how she goes. The short barrel may or may not be a handicap- you just never know, all depends on the individual barrel.

Yes, a sturdy bedding job will be called for. There is just too much recoil with full power loads for the wood to last without some movement, especially in Canadian environmental conditions. A crossbolt is not completely necessary if using the likes of our compound as it really is as hard as steel. The trick is to avoid piddly skim bedding jobs.

I am not sold on the scope you fitted, the eye relief can be short on this model if memory serves. Check on this when you get a chance please- I could be right or completely wrong. You need to be able to get your fist between your brow and the eyepiece of the scope.
25 Jun 2015
@ 11:05 pm (GMT)

Mike Dewey

Re: BRNO ZKK Project
Thanks for the reply Nathan. Have some of your compound from another project. Ordered two just in case...

Wondering about relief between the front 'pillar' and the threaded projection under recoil lug. Contemplating just filling gap with compound then Dremelling out some relief if needed. What think?

The Leopold 2-7 x 33 VXR is maybe a newer version of what you're thinking of, I can easily fit a fist between brow and rubber eye piece. Put probably close to 150 rounds through without trouble off a rest or sand bags. (Already have a crescent scar over my right eye anyway.)

Wanted 4895 but have to take what is available. Tried 4350 but couldn't get enough into a new case to get dangerous.

Looking forward to your take on 9.3 bullets although Nosler partitions will be my go to for larger game and will likely try the PRVI round nose on deer as softer and should open up quick.

26 Jun 2015
@ 09:40 pm (GMT)

Nathan Foster

Re: BRNO ZKK Project
Thats one way to do it. If a lug is really fiddly, you can try using a thick and bright colored nail polish on the bottom of the lug or areas of the lug, then release agent. After the bedding is complete, use a nail polish remover. This can work well on the Ruger M77 as an example.

Good to hear the scope has plenty of relief.

Keep an eye open for any light bullet options for deer. The European stuff is unfortunately pricey these days which is a shame but still, keep an eye out for anything around the 225-232gr mark to get the most out of the rig on White Tail. Heavier bullets will certainly do the job but the lighter options do it with style. Marty also put up a post regarding swaging the 225gr .375" Interlock down to 9.3. That's an interesting read if you have time.


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