when you have the bolt locked back and you hit the stock right on the end does the bolt release. mine does with or without a mag. its a panther AP4 pre-ban with the ajustable stock.

Yes it's normal without a magazine, but it shouldn't with an empty mag. I'm sorry I don't have an answer for you as to why it does it with a mag. I am assuming you mean it does it with an empty magazine.

Mini 14 did it
Mini 30 did it
M1 did it
Havent tried my AR15`S

I believe what you are describing is defeating the bolt catch by inertia.

The bolt catch is lifted up into the path of the bolt by the follower after your last shot. (Or can be engaged manually)  The bolt travels well past the bolt catch during rearward movement, the bolt catch comes up as the magazine follower engages it after the last shot via the power of the magazine spring.

As the bolt returns home, it is caught by the bolt catch. The bolt coming to rest against the BC via the action spring.  When you slap the ass end of the weapon aka the butt of the rifle, the bolt is "bounced" backwards, relieving the pressure from the bolt catch.  When the pressure is relieved, the bolt catch returns to rest in it's downward position via the bolt catch spring.  You can perform this with and without a magazine inserted, but not with an empty magazine as the follower will hold the BC in the upward postion.  With the loaded magazine, it will strip the next round into the chamber.

If you can do it w/ an empty magazine- you have a weak mag spring or other woes such as a defective follower.

HTH,

Sly

ETA: That is why it is not wise to store you're weapon w/ loaded magazine inserted and bolt locked open.  A bump to the butt of the rifle and you're rifle will chamber a round...  Couple that w/ a primer strike via inertia on a soft primer, you just might have more fun than a Barrel O Monkeys...

I refer to the method above as "Spanking" the rifle...  What on earth did your AR do to deserve a spanking?

Sly

it does it with a loaded mag haven't tried it with and empty, an empty mag is useless