Gents just wondering if the factory CZ straight american stlye safari stock( not the older style garbage hogsback CZ first came out with) is strong enough to handle a large calibre conversion?

I was toying with leaving the original stock on a CZ550 416 rigby I am converting to 530 calibre ( weatherby case- 500 A2-ish power). Its a cheap fun gun, and stock idea is laziness motivated really, too hard to get the B&C style here in Australia Any thoughts or guesses on how it might go?

My ZKK602 458Lott with original factory stock has held up so far (a rechambered 458Win issued to Jon Speed when he was a game ranger in Tanzania).
If I were rebarreling a 416 CZ550 to something bigger, I would add a barrel mounted recoil lug.

Sure it will work, as long as the wood is good.
Proper grain in the grip area is important.
The laminate Phat American CZ may be heavier, and eliminates grain concerns in the grip area,
but it is still subject to longitudinal splitting within a lamination.
Take care of that with proper cross-bolting, secondary recoil lug on the barrel, pillar bedding, and relief of the tang.
Do that to either good-grain-flow walnut or laminate.
Also add an axial bolt (allthread in epoxy) through the grip,
for the +50-cal.

Here is a 500 Mbogo (.510-cal, 3" Rigby) with a laminate Phat American stock so treated, it is solid:



Here is what happens with a Phat American walnut stock when the grain flow is bad in the grip.
In photo below, at top a gentle little 404 Jeffery breaks it grip,
but with better grain, the .505 Gibbs holds up (bottom):

Several years ago, I had one of the early CZ .505's before they started adding crossbolts from the factory. Even without the crossbolts, I never had any issues (probably more luck than anything else). I eventually sold that rifle to ISS, and can't remember ever reading of him ever having any issues with it, either.

Now that I'm a little older and wiser, if I had it to do over again, I would definately take the time to set it up the way RIP described in the previous post. Follow those steps and I doubt that you will have any problems.

For a hard kicker, the sheetmetal factory box must be reinforced at the front. Otherwise the bullet noses will batter feed-stopping dimples into the front of the box.
Rusty McGee did these: