Can Jumbo coteunix hens varying aignificantly in size?

[SMMS3617]

Hello,

I have 8 Jumbo Coturnix hens that i got when they were about 4 weeks old and now are 18 weeks old. I've noticed some variety in size amongst them and I haven't tried weighing them yet. But there is some significant variation. They have constant access to a gravity-fed three-port feeder and they live outside in a metal pen.
Is it normal that some may be smaller? At what point do they reach adult size?

Thank you in advance.

 

[Kiki]

Males are usually smaller.
Can you post a few clear pictures of your birds?

 

[SMMS3617]

Males are usually smaller.
Can you post a few clear pictures of your birds?

I will tomorrow in the daylight.
I've checked my birds to see them, and I haven't noticed any displaying male behaviors. So I'm pretty certain by now that they are all hens

 

[Nabiki]

Coturnix normally reach their full size by 12-14 weeks. There can be variation in size, especially if they've been in any situation where larger, more dominant birds can keep smaller ones from the food.

 

[Charlie Wooster]

They may or may not all be jumbos, standard Coturnix and Jumbo Coturnix look alike until you really pour the feed to em.. next question is what are you feeding? At 12+ weeks they are fully mature so definitely by 18 weeks they are full grown.. show some pictures front view and side view if possible..

 

[SMMS3617]

They may or may not all be jumbos, standard Coturnix and Jumbo Coturnix look alike until you really pour the feed to em.. next question is what are you feeding? At 12+ weeks they are fully mature so definitely by 18 weeks they are full grown.. show some pictures front view and side view if possible..

I have them on a layer feed, 16%: Scratch and peck feeds layer mash.
I have noticed the queen of the flock, she is super curious with everything I do and she will go after the others if I throw them worms or treats to take it away.