Pick up the SMLE ( Short Model Lee Enfield) , the standard arm for the British soldier in WWI, and it very much feels like a club: it was something that was designed to be treated very roughly. Military rifles were supposed to be durable. Hunting rifles regularly get broken ( lots of graceful Kentucky rifles have been broken through the wrist, a weak spot) but the hunter isn't going to expect to fight with his rifle like a club to survive, vanquish a deer. A hunter is happier trading off some of that durability to reduce the weight of the gun, in order to be able to carry it further, so sporterized military rifles typically will have the stock cut down to a half stock, and, since the gun isn't going to be used as a pike, a long barrel is often cut down as well. Maybe one of the better examples of this was after WWI, when the NRA bought a huge number of obsolete Krag Jorgensen rifles from the US government and re-sold them to its members, wanting to improve civilian marksmanship. Each had the barrel and stock shortened first.

Also important: the hunter is not going to let off a quick hundred shots in a firefight. Put a dozen rounds quickly through a high-power rifle, and you will notice the barrel getting warm. The full stock on a military rifle also keeps your fingers from getting accidentally burned. Even the AK-47 or AR-15 ( which also are cut down and designed to be lighter than older weapons like the Garand) have stocks designed to prevent that.