Thread: Switch barrel Brno Fox

Hi All.

I'll add photos later on and build this up.

I had a Brno Fox 2 here in the safe which had a .17 mach iv barrel on it I got the rifle off an elderly friend who could no longer keep his licence. Being in South Australia (here for 9 years now) I couldn't even test shoot it with out lodging a permit to acquire as it was at a gunshop for safe keeping. So it took 6 week for the permit to come through. I've shot a few foxes with it and bunnies (also the occasional skippy) and had it for nearly 3 years now. I saw Wingman's thread on his switch barrel CZ527 and it got me thinking.... I've always wanted a 300 Whisper/BO so a couple of pm's to Wingman (probably should have been more) I dropped the barrel off to Sprinter Arms 2.5hours drive from me. By this time I had also found the original .222 barrel the rifle came off that had done minimal work .

Sprinter is a barrel maker and I have a stainless 1:12 twist on a BSA Hunter in .222

So the spec was to fit a 300Whisper barrel to the Fox and set it up so I can switch between 17mach iv, 222 and the Whisper. The Gunsmith wasn't keen on a hand tight setup for the barrel seating so they do require some torque on them.

Flats were machined on the sides of the barrel for removal with a spanner. When I post the pictures up you'll see some machining marks visible, I'm not worried about the looks but the whole job cost $650 and was turned around in 5 weeks .

More to come.

thats a cool idea, Im guessing theres no chance of suppressing the 300Blk with auzzies stupid laws?

Originally Posted by Bill999

thats a cool idea, Im guessing theres no chance of suppressing the 300Blk with auzzies stupid laws?

We live in hope but doubtful

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Oh Bill we shouldn't throw rocks bud !

Not the way ours are going !!!


Actually we may be down to throwing Rocks in the end lol !

Not so funny either really !

Pics

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The shanks of the 3 barrels
Unthreading 300whisper barrel, barrel is loosened with a spanner I didn't take a picture but it works better with the barrel held in the vice and spanner going over the top and bottom of action next to the scope ring. I'll slip the scope ring further forward.
Original 222 barrel spun in
And now I've hit a problem the ribs inside the magazine will not allow more than 1 round in the mag as it the projectile contacts the side of the magazine.
I will find another magazine and will cut out the centre of the rib and trim the length down so it will become a 3 round magazine.

Did the smith stamp any witness marks on the action and barrel to align for repeatable head spacing? All of those cartridges only have 2 thou between go and no go so it would be very easy to get it wrong without some marks to line up. I would have thought he would have milled some tidy vertical flat slots for a spanner closer to the shoulder rather than ramping it off with a file like that or better yet used a grub screw through the action into a dimple of the barrel thread section which means they could be changed without removing the action from the stock each time.

Interestingly I also see the .300 whisper barrel and .17 Mk4 barrel have been externally shouldered, the 300 whisper also has a deep thread relief cut, this is not a good way to set up a Fox/527 as they are designed to headspace and pull up square against the internal machined face in the action to the rear of the tenon face. The outer front of the action is not machined flat or square to the bolt/lugs. It is best for accuracy to machine the knox right down to 26mm like your .222 barrel to allow the barrel to seat on that internal machined shoulder only where it is supposed to.
I know you said you weren't worried about cosmetics but as a gunsmith he should have a bit more pride in his work than that.

Did I send you those pics of how to mod the mag for .300blk?

Hi Wingman

Yes there are witness marks on the underside of the barrel and action.

The 17 barrel had been setup with the shoulder in the early 80s. My preference was to have the barrels the same as the Brno original without the shoulder and once I have had a play I'll get someone closer to me to turn the shoulders down to 26mm to match original.

No you hadn't sent through the mods for the magazine to suit blackout.

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I cant seem to find the mag mod pics other than this one




https://www.nzhuntingandshooting.co....-length-60532/

Did the 'smith' do those flats with an angle grinder? I dunno if I'd be particularly happy with that work to say the least

Originally Posted by Tommy

Did the 'smith' do those flats with an angle grinder? I dunno if I'd be particularly happy with that work to say the least

Don't know haven't looked hard enough not all that tidy though, put all three barrels in and out to see how much tightening they needed to index properly then put the 300 whisper barrel on and went and sighted it in. Of course there would be a horizontal difference between the supersonic and sub loads to make it more interesting. 100 yard zero for the 125grain bullets works out to first hash mark on 6x for the 190 grain sub-x load using the bdc reticule and 2 inches right close enough to use the right edge of the hash mark as aiming point.

I'll get the barrels with the shoulders turned down to match the 222 barrel and the eye sores will be tidied up when I go back north and past the workshop, after I have shot a deer or two with it.

Originally Posted by Wingman

I cant seem to find the mag mod pics other than this one

Attachment 144259


https://www.nzhuntingandshooting.co....-length-60532/

Ahh shit, when you don't subscribe to your own starting thread and miss some vital information

@Tuidog, if your rifle is shooting well with the externally shouldered barrels, leave them as they are .

When I rebarreled my fox, I trued the front face of the action and set up the shoulder on the front instead of the back and it shoots very well like that.
Technically, the Mauser 98 ( like the cz527)principal of having an internal abutment to tighten the barrel against is very good and helps to get away with a shorter threaded length. The Barnard action has both , an internal abutment and the front face of the action.
Most of the rest of the rifles have a front shoulder abutment.

Originally Posted by Friwi

@Tuidog, if your rifle is shooting well with the externally shouldered barrels, leave them as they are .

When I rebarreled my fox, I trued the front face of the action and set up the shoulder on the front instead of the back and it shoots very well like that.
Technically, the Mauser 98 ( like the cz527)principal of having an internal abutment to tighten the barrel against is very good and helps to get away with a shorter threaded length. The Barnard action has both , an internal abutment and the front face of the action.
Most of the rest of the rifles have a front shoulder abutment.

Yes.. what he said.
If you turn the shoulder off now you may have to ream the chambers again to reset the head space depending on how your smith has set them up. My Desert tech barrels mate up on both faces like the Barnard too but the difference here is I doubt the front of your action has been trued to the internal face.
Just shoot them the way they are, its a hunting rig not a match rifle.

man it is nice to see two professionals AGREEING with each other and being polite too.......
its a neat concept but a .223 would do the job of all 3 without faffing around LOL.