Don't know how much is average on a BCM, but that is one reason I thought I would breed to my EE's and also got a few purebred BCM. Well, It has been a crazy year because my first to pullets went broody before a year old. they will be 2 june 27, and I have already had to break them both again. I have a crop of 1 yr old pullets that are half BCM and white leghorn (5) now 1 yr old. All 5 have been broody multiple times since they were only 7-8 mo old. Really! white leghorn and BCM broody constantly. Now I am breaking EE's from going broody. 4 so far. Never had so many go broody, usually NO or maybe 1 EE go broody. Buff Orpingtons and Barred rock I always had 2 of each go broody each summer but only one time each, not constantly. I no longer have the buff's or barreds. But I will likely get me some of those again next time. Mine did hatch some chicks, but I don't have the space for this constant broodiness Hope someone that Has FBCM and breeds them will come on and tell you more. Good luck.