I found a Brno ZKK-601 at auction in .25-284 caliber. The description says the bore has corrosion and the rifling is worn. I am thinking this would make a good candidate for rebarreling to something like 7mm-08. The plus is that it is a CRF rifle.

Ammo is readily available for the 7mm-08 and it is not outrageously priced. Unlike the .25-284, I wouldn't have to reform brass, buy expensive dies, or even reload.

How hard is it to rebarrel a Brno? I would have a gunsmith do it.

Gunsmithing question.
Done many of them; just like anything else, it is easy, with Metric threads. Not inch. If you can't cut metric threads, then it would be hard. As in, impossible.
CRF? Way over hyped. I never got the advantage in a sporting rifle (military, with untrained soldiers, which is why it was developed, yes), and I have hundreds of them.

First I would try some 7mm08 rounds in the magazine to see if the rails will keep them down. The Win 284 case is fatter than the 08 case and may have had the rails opened up. Just confirm before committing to a rebarrel to the 08 cartridge, which by the way is a good choice.

I had someone mention that could be a problem elsewhere. By my calculation, the .284 rails would be .021 narrower than for the 7mm-08 to account for the wider cartridge.

If .284 were still common, I'd probably go with that.

It will still work with 7-08.

I need to make a correction. I made the wrong assumption that it was a Brno ZKK-601. The action is either a Brno M98/22 or vz24. I should have looked more closely for a picture of a ZKK-601 before I assumed it was one.

Then it has inch threads,1.1 inch OD and 12 TPI and makes it easier. For some lathes.

I would go straight 284 win.

The 6.5-284 would also be a great candidate.

+1 for 6.5-284, have it chambered in no neck turn and brass is available from Lapua. It is a stunningly accurate round without faffing with cases. They like common powders too.