How do I know if I can put an Apo Ronar in a #1 compur ?

[Laurent]

Hello,

I've seen a not-too-expensive 300/f:9 Apo-Ronar but it is in a barrel.

How could I identify if it would fit in a #1 Compur I happen to own ? SKGrimes reports there are several types, so I'd like to avoid buying the wonrg one.

Thanks in advance

 

[bnstein]

Im not sure if you can short of having someone spin out the cells and measure their diameter. I have one of the wrong ones!