How effective is a 32 inch barrel for slugs on a 12 gauge Browning Auto-5 and what is the best slug length to use?

Please dont shoot slugs through a 32" barrel A5. That is undoubtedly a full choke and shooting slugs through it can damage that barrel, which by itself is worth $300. Slug barrels are typically 24" in length with an Improved Cylinder choke.