On an bit of a side note ...... A couple of the 35WHELENs I've owned upon firing full 250gr loads at the bench would open the chamber on it's own. I've even had on one or two occasions the empty brass fully eject and fall to the side of the rifle.
At first I was quite concerned about this, but the rifles functioned perfectly otherwise and later found out online that other had had this same experience in their 35s.
This may be a function of how you hold the gun. I've had more than one 7600 and big marlin lever come part way open when shooting from the bench, but never when I'm standing on my hind legs to shoot.
