Bolt action overheat

There's not much of a reason that I can think of to shoot a bolt action hunting rifle that fast, that much. Military rifles are different. It's like saying that because I can drive my Vet a hundred miles an hour from Houston to San Antonio then there's no reason I couldn't do the same with a Ice Cream Truck. I've fired a G3 until I couldn't hold the forearm, the gun was designed and built for it. When I really hunted a lot I might have fired 5 to 6 rounds a Deer Season, I'm sure I never got the barrel on a deer rifle so hot I couldn't have put my bare finger against the barrel.
 
tobnpr, a skinny sporter barrel won't string shots as it heats up either. Lenght and thickness doesn't matter. The only thing that does is how the barrel's stress relieved, how external forces on it change as it heats up.
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I guess this is akin to barrel cleaning, where there are many opinions.
Dan Lilja thinks differently (and like I said, his is only one opinion, but one that I respect)...

He does believe that rigidity- obviously a function of length and thickness, does matter:

In another article on barrel stiffness, we outlined the mechanics and math behind barrel rigidity. The simplified version of that article is that a barrel too long for its diameter is not rigid. It can be whippy and accuracy will not be at its best. Generally speaking, a short and fat barrel is more accurate.
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And while I agree that there is more "to" the "skinny barrels heat up and string shots" generalization, I still believe that due to the fact that they are less rigid, any residual stress in the steel will become more evident as the barrel heats up- and strings shots- due to the simple reason that they are less rigid.

I do believe that this would be less evident, in a "skinny" (factory) contour barrel that is of high quality, likely cut rifled and made from stress-relieved steel.

But the stereotype persists- and like most- has some merit- because most light contour barrels are mass produced, not stress-relieved and of high quality, and will be more likely to string shots when hot.
 
most light contour barrels are mass produced, not stress-relieved and of high quality, and will be more likely to string shots when hot.
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I'm glad I caught this post. I thought it was pretty much accepted fact that barrels tend to change point of impact when they got hot, whether stringing or just opening up. When I lived in the South, I just quit going shooting if the temp was above about 90, 95 degrees because like clock work, after 4 or 5 shots my Rem 700 ADL in .30-06 groups started opening up. I typically waited 3 minutes between shots with bolt open. I also noticed that it was about this time that the barrel was too hot to touch.

My barrel is free floated, but action not bedded. I loaded bullets one at time directly to the chamber and kept the rest of them grouped in the same temperature (usually in the shade) and the time in chamber between loading and firing was consistent.

Now in the winter, with an ambient temp of more like 30-40 degrees, if I waited 3 minutes between shots, I never noticed the group opening up (unless it was me of course..). For those of you who say that temps don't open up groups, can you offer any explanations as to why I got the results I did?

But to the OP, if its possible to overheat your rifle, you were no where near it. You would have to do something ridiculously absurd (like fight off the Turkish Army.. great story tiki!) to get there.
 
Here's two barrels fit to receivers bolted in a stock; both 30 caliber. The bore diameter of .306 inch was used to equal what a typical 4-groove area of .308" groove diameter would be (.0736 square inch). My software only uses one diameter for the bore. Use the profile below for dimensions listed:

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First barrel, typical 24" sporter rifle:

bore diameter = 0.306 inch
breech diameter A = 1.25 inch
reinforce large diameter B = 1.25 inch
reinforce small diameter C = 0.8 inch
muzzle diameter D = 0.6 inch
reinforce length AB = 2.75 inch
reinforce taper length BC = 3.25 inch
main taper length CD = 18 inch
total length = 24 inches
total weight = 3.191 lb

Second barrel, typical 30" Palma rifle:
bore diameter = 0.306 inch
breech diameter A = 1.25 inch
reinforce large diameter B = 1.25 inch
reinforce small diameter C = 0.92 inch
muzzle diameter D = 0.82 inch
reinforce length AB = 2.5 inch
reinforce taper length BC = 2.5 inch
main taper length CD = 25 inch
total length = 30 inches
total weight = 5.095 lb

Which one's stiffer and by how much?

One of them vibrates at about 71.5 cycles per second and that's about the frequency where the greatest amount of bore axis angular spread happens at the muzzle as it whips in the vertical axis for that barrel's contour. It goes through one cycle in about 14 milliseconds. Bullets take about 3 milliseconds to go from case mouth to out the muzzle.
 
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The exception to the rule that a little copper is good for a bore is when shooting Barnes all-copper bullets. Sometimes they foul barrels in 10-20 shots, not all barrels, but my .270 Win accumulated so much that pressure was raised and primers flattened, bolt opened harder, and velocity changed. (Coated TSXs may not foul, but I haven't tried them.)

It was also difficult to clean the bore. I could feel the roughness as I cleaned it and was concerned that it wouldn't come out, but it took many bronze brush strokes with solvent to get it clean. I now use Hornady GMX (Gilding Metal) bullets that work just as well as the Barnes TSX on game, but don't foul the bore.
 
Kraigway can probably correct me but, my recollection is that the old M-60 barrels could withstand 5minutes of sustained Continuous firing before the barrel started to droop.
 
Barrel droop?

Reminds me of the old mechanical computers used on battleships and heavy cruisers that had compensating cams in them to correct for 8", 12" and 16" barrel "droop." Their muzzle axis was actually below the breech axis which is used in the primary elevation calculations for where to point the gun to hit the target. Barrel droop was greatest at zero elevation; got less as the gun elevation angle went up. Which is what the droop cam corrected for in changing the elevation gun orders just a smidge to correct for it.

Shoulder fired rifle barrels also droop from their own weight even while at ambient temperature. Put an optical collimator in the muzzle, zero the sights on the collimator with the barrel in the vertical, then lower it to the horizontal and watch the collimator reference go below the sight axis.
 
probably need to clarify. The barrel droop was caused by over heating the barrel to the point the metal lost its strength. In the "test" I saw the muzzle literally moved down about 2 inches.

My point is that I do not believe a bolt action rifle can be fired fast enough for a long enough time to damage the barrel do to overheating.
 
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I am more concerned with throat erosion than the barrel looking like a boiled noodle. A bold gun could not reach the heat that the M60 does, but I would be curious as to how many shots it would take till the throat is gone in the M60.
 
My point is that I do not believe a bolt action rifle can be fired fast enough for a long enough time to damage the barrel do to overheating.
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I know of at least two instances when a new barrel was fit to a 30 caliber magnum 1000-yard match rifle and the owners thought they ought to be "broken in" with several shots. Both had several dozen shots fired 5 to 6 seconds apart.

Sighting them in at the range with scopes installed, neither shot under 2 MOA at 300 yards. Normal for such barrels and ammo was about 1/3 MOA. Bore erosion gauge inserted in their throats showed the same amount of wear as a .30-06 after about 6000 rounds. They were now not fit for competition.
 
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