From what I can find 0.687 construction falls into the extra full Remington Turkey choke category.
Pattern that.
I use a Hastings Extra Full Turkey choke on a Rem 21" cantelever slugger barrel (is Rem choke compatible) and my choke is 0.663 constriction.
And to shoot buckshot. I
I would use a Modified choke.
Do Not use a Turkey choke.
If you are going to hunt deer. Use a savored slug. Far more accurate and lethal.
Purely my opinion.
JW
That's a " Saboted " slug, and they are designed for fully rifled barrels.