I do think there is some variation in Bur oak acorns in the depth of cap and some of them even have a shallow enough cap that some of the acorns fall free. Those are the Bur oak acorns I’d plant if I were to plant Bur oaks for deer particularly on large acorns but I could be completely wrong and the deer chew threw the large caps to get to the acorns no problem idk. This is why I normally don’t plant Bur oaks in my deer orchards.