Attaching rifle to pack

[Hunter mike]

corral gunslinger, best $35 you can spend to pack a rifle!!!!!

How does this work wearing a full external frame pack?  I really like it for having the option to use it without the pack on day outings as well. 

Thanks everyone for the replies - lots of good ideas!

[fillthefreezer]

works killer! just hook it to a compression strap down down low and put the grip of your rifle in there, the loop a top compression strap and barrel up high and good to go