Gosh, I haven't even given this a thought for years. I never did name a rifle, but I had two old H & R single shots that I did name. One was a 10 gauge mag with about a 36" full choke barrel named "Big Ben". or just Ben for short. The other is a 12 gauge 3" mag which I sent to Marble Arms for a vent rib and poly choke - total barrel length is 19", if I recall. It is legal - neither I nor Marble Arms would have it any other way. Named it "Hubert". Hubert is very compact and seems to weigh about 5#. With a 3" magnum load, it is easily the most punishing gun I have ever shot, and I have shot .460 Weatherbys.
Used to keep "Ben" in the duck blind for geese. Sold it over 25 years ago. I still have Hubert. I don't know why, after all the guns that I have owned, I named these two.