Shouldn't be a problem. You will want an open choke though, like an Improved Cylinder or Modified choke. You can use a full without damage to the weapon but it will deform the slug pretty bad and accuracy will probably not be that great.
I would suggest setting the friction rings to the heavy load set up and wiping any oil off that may be on the magazine tube. Then see how it cycles, if it jams maybe add a VERY light coating of oil with a rag and see if that helps. With an A-5 you always want the heaviest recoil setting you can get and still get consistent reliability. Since they are recoil operated it is better on the action in the long run. That being said they can take a significant amount of abuse and still last for decades.
Keep in mind it will recoil, slugs will not feel the same as a field load when you pull the trigger
.
If you want better accuracy I would suggest getting some fiber optic clamp on sights that go on the barrel rib. Shooting with a bead sight and slugs takes some pretty great shooting form. You have to be lined up with the bead perfect and have a very repeatable cheek weld to the stock to pull it off.
Don't bother with a scope or any other type of sights mounted to the receiver since the barrel recoils on every shot I don't see them being very consistent.
Don't be afraid to try different slugs as well, it will like one brand or type over another most likely. Don't shoot sabots out of it either, complete waste of money in a smooth bore. Stick with the rifled/foster slugs. I have good luck with Winchester slugs, but the brenneke/rottwiel slugs are pretty popular in the U.S. so I don't think there is anything wrong with them.
I have an A-5 stalker light with the 22 inch barrel and with clamp on sights off from a bench it will group around 5 inches at 100 yards. I wouldn't expect that from every gun though, I think I got lucky with mine. Some can't do that good at 50 yards.
Good luck,
Paul
