Live to dressed ratio -- bourbon reds and Narragansetts

[brandywine]

No nibbles on this question over on meatbirds, so trying here.

I'll be butchering five toms -- 3 bourbon reds and two Narragansetts -- for Easter, and am trying to get a sense of the dressed weight to expect.

They range from 17-25 pounds live.

Anyone got a formula, chart, etc. on the relationship between live and dressed weights for heritage birds?

 

[turkey guru]

take live weight, less 38% thats your carcass weight!!!!! tom!!!

 

[brandywine]

Thanks -- so if 62% of live weight is the rule of thumb for heritage birds, what is it for broad-breasted?