I can only speak of spitfires, but as long as the broadhead is going forward the blades stay open, the second they are pulled backwards they close. Trust me on this one, I spined a deer with a spitfire this year, perfect triangular cut in the hide and all the way through the meat, when I pulled the arrow out it pulled real easy, I thought what the heck, the blades were closed, then with a thick glove on I verified forward open, backward close, everytime, they do not lock open.

The Tazman aka Martin Price
Proud father of a Devil Dog