Form question: back muscles

[FrankM]

I see that you pull your back muscles together to "set" your form.

But when you begin to fire, do you pull your back muscles together more with the arm moving back? Or should your back muscles already be as together as they can go and you only move your arm back?

[magnus]

You might get quicker answers if you post this in the shooter's forum.

[FrankM]

OK, did that, ignore this thread. Thx!