Please settle a dispute between two hunting buddies……
My friend says that by firing the top barrel first on an over/under shotgun causes severe stress on the firing mechanism and can eventually lead to spring and or firing pin breakage. I say it’s a matter of preference – that the stress is the same regardless as to which barrel is fired first.
What does the Technoid say?
Well, you are both wrong, but you are less wrong than your pal. (Remember, the guy who is telling you this has “Often in error, never in doubt” as his tag line.) Firing the upper barrel first does put a bit more stress on the action, but it really doesn’t affect the pins and springs.
Much of action stress depends on the design of the O/U- whether it uses a full hinge pin (Browning) or bifurcated lumps (like Beretta and Boss) and also whether or not it uses some top latching mechanism (shroud, cones or cross bolt). The further away the top barrel is from the hinge pin, the more stress it will put on the locking mechanism.
That said, the Belgian Browning is considered by many to be the longest lived O/U ever made. It has a low hinge pin and an equally low locking bolt. Beretta’s system with hinge points almost between the barrels and locking cones near the top of the breech has a theoretical mechanical advantage. In practice, it doesn’t seem to be any stronger than the Browning.
As to spring and firing pin breakage, I really don’t see how that would be affected by which barrel is fired first. Any trigger plate lock gun like an O/U is going to have more trouble with the lower firing pin due to the angle required by the design. That’s just built in.
Most O/U shooters prefer to fire the lower barrel first because it keeps the first barrel recoil lower in the gun’s axis and there is less resultant muzzle jump.
Shotgun Report’s Technoid
(Often in error, never in doubt.)
The fact that nearly all fixed choke O/Us made for trap shooting and I guess most field guns also had the more open choke in the lower barrel would suggest the gunmakers also believed this should normally be the first one to fire also (given the fact that all trap shots are closer for your first shot and further out for the second with the target going away from the shooter generally the majority of field shots are like this also except of course ducks coming in to decoys etc. these situations are where you would flick the selector over to fire top first generally, these days you could just swap position of choke tubes to suit