[LookinSharp24]

I'm between a 42-43R as my chest measures 42.5".

That said, most measurements are pit to pit thus I need to look for 42 & 44 tag sized but what should I be looking for in a pit to pit measurement?

I'm thinking ~22.5"?

 

[LookinSharp24]

The problem with looking at the tag size when shopping eBay is that there's no way of knowing the nature of any previous alterations.

I believe you alluded to something like this is another thread.

As for methods for "nailing the size", I agree with the above.

I did. And what's odd is the jacket that fits me well seems to measure 21" pit to pit and yet when I measure my chest I'm ~42.5".

Makes no sense to me.