I didn't unequivocally state that it would, nor did I mean to give that impression. I stated that heat was the issue - manage throat/bore temps and you will manage your barrel life. In very underbore chamberings, lots of rounds fired in very rapid succession may never cause excessive bore temps whereas very overbore chamberings might need significant temperature management.
In the case of the OP, I'm not certain that you can work the CVA break action from the bench fast enough to really damage the bore by shooting quickly. I also expect that the accuracy of the gun will be influenced more by other factors than barrel heating.
I agree. Even in the best case (2-3 rounds, fully cooled) you are only going to slightly delay the inevitable. You aren't going to squeeze 10,000 rounds out of a 300 win mag or 7mm mag by being conscientious of temperatures. You might extend the life a smidge, but not by any meaningful amount. (On the flip side most dudes are far more likely to *damage* a barrel by cleaning it incorrectly, e.g. from the muzzle end, or with a cheap 3 part rod or whatever).
You are absolutely correct in that overbore is going to wear the barrel out faster but I seriously doubt one is going to extend barrel life in any meaningful way by firing 3 shot groups vs. 10 shot groups. (would be an expensive and rather tedious study with a comparator gauge to figure out).
Instead overbore wears barrels faster because of longer sustained high pressures. You're pushing the living snot out of that projectile (e.g. 22-250). My belief concurs with yours - on a bolt or semi-auto gun you aren't going to work it fast enough to contribute meaningfully to the rate of throat erosion. Heat has much less to do with this than the pressure and friction of the projectile. That section of the barrel is subjected repeatedly to the absolute highest pressures and friction factors as the bullet is cut in to by the rifling and the projectile shapes itself to fit the barrel.
This is why you see even well-treated 22-250's and belted 300 Win Mag wear out FAR more rapidly than a 223 or 308 or 30-06 barrel. I considered myself fortunate I got about 2k rounds out of my last 300 win mag barrel before I had Kreiger cut me another. I quit shooting my laser-accurate 22-250 for pleasure and reserved it for purely for hunting use only after about 1500 rounds.
I was always taught to not let the barrel get too hot to touch for best throat life and I still follow that as I have patience and respect for my rifles.
When you fire a round the pressure and heat is truly immense. Feeling whether the barrel is "hot on the hands" isn't a good gauge to go by. The steel has to exceed several hundreds of degrees (500+ depends on alloy) to start the annealing process again which will change it's strength. It'll be glowing in a dim light at that point, and would melt the skin right off your fingers. The heat in the chamber (which isn't soaked and removed by the brass itself) is VERY rapidly transferred through the awesome metal conductor that is the barrel.
Throat erosion on full auto fire is a big concern, which is why most military rifles switched to chrome lined bores. More durable. Prior to that, on sustained cyclic fire, certain weapons would wear out in 1,000 or 2,000 rounds (earlier than chrome lined, there were water cooled machineguns, others had air-cooled fins, such as the MG-37, Soviet DSHK, etc). But you're talking about sustained fire, with no chance for the barrel to "heat soak" and spread the heat out. That doesn't take long, as steel is a reasonably a good conductor of heat.
I would argue that the full auto throat erosion issue has much less to do with sustained fire than changing the steel itself. When you heat a steel barrel above a certain temperature and then allow it to cool slowly, you anneal the barrel. You literally make the steel softer. In a barrel with a hot core and cool outside this will soften the inside (rifling) faster than the outside. Subsequent rounds will burn through the rifling even more than before, because the steel has been softened through the annealing process.
Chrome moly has FAR higher annealing temperatures than carbon steel does. You can heat it 3x as much or more without making it "soft" and more prone to wear. Thus full auto guns last longer - the barrel lining doesn't become soft with repeated high temps (barrel core 700F+) and slow cooling.
You *can* get a semi-auto to that type of temperature but - speaking from my own personal experience - my trigger finger generally wears out and I can't pull it anymore well before the barrel gets that hot. (I did manage to get AK-47 grips to smoulder once but that was on a real hot day after 3 successive 75 round drums.)
You are *not* going to get a bolt action or break open action that hot. I don't care how fast you shoot it.
Bottom line, to damage the steel itself and promote faster throat erosion, you have to get a barrel up to annealing temps. That way the pressure and friction wear are accelerated.
I was curious if there is a recommended max barrel temperature before wear begins to accelerate so I did some searching and could not really find anything except to a reference to the field manual for an M14. It gives the following recommendation.
Rates of fire. The following rates of fire can be maintained without danger to firer or damage to the weapon. This is of course specific to an m14 in 308 and I don't know if there standards for not damaging the rifle mean "didn't erode the throat for 5000 rounds", or if it means "did't set the handguards on fire"
That's the max rates of fire for "I'm going to become hot enough to start cooking off my own rounds and run away on you" table.
