Originally Posted by ajstrider

I do not know the rifling twist on your barrel, but it is common that slower twist barrels stabilize the bigger bore size slugs better. A faster twist barrel will stabilize the newer fancier ballistic tip slugs that are actually smaller diameter better. I know you said you tried a variety of ammo, but if you only tried the newer fancier ballistic tip type slugs, you aren't really trying the biggest variety of slugs out there. You should go get some of those gigantic Brenneke slugs and see if those shoot any better. If you already tried this kind of giant bored slug, well then, I would just zero it at 100 yards and accept the fact that at 50 yards you might be a little off. Better to be off a little up close than a few more inches at 100.