I have a question about getting a barrel to hot. I have been told not to get the barrel of my rifles to hot. If you can't put your hand on it comfortalby then the barrel is to hot. Is that about right?

Another question is what happens when the barrel gets to hot?

And does it make a differance on what rifle you are shooting. For instance a 22-250 or a 22lr or wiill it do the same damage with either?

If you get it hot enough, erosion (wear) will be greater. Barrels genearly don't "wear" out, they brun out from the breech....hotter yu let them get, the faster that is going to happen (but it will happen sooner or later no matter what).

Hot metal expands...which changes the contact points.

A free floated barrel has no contact points, but you aren't home free yet. Barrels often have internal stresses...as they heat, these stresses can make barrels warp slightly...and that will "walk" your point of impact.

In at least one test by a barrel maker, if the barrel blank before rifling is stressed, even if the rifling and chamber job goes perfectly, the barrel will tend to walk its groups as it heats up.

YEs...all barrels heat...but considering you are burning about 3gr. of powder at a shot, ate much less pressure, with a .22LR, it takes a whole bunch of shooting to warm up one of those barrels.
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Something to think about. Fat barrrels heat slower than thin barrels (more mass). Thin barrels cool off more quickly than fat barrels (more surface area for the mass).

Sorta hard to get a .22LR rifle REAL hot, due to the reduced charge and the soft lead bullets not causing all the friction heat of a larger jacketed bullet.

Yes, if you continue firing a rifle with today's chamber pressures exceeding 40K for the most part, you're contributing to faster bore erosion and wear than if you will pace the shots and keep the barrel no warmer than what you can hold with the bare hand comfortably.

Having said that - where I live, just ambient conditions can warm a barrel up to uncomfortable temps, even without firing the rifle. Have learned to take a 12 pac cooler to the range with previously frozen hand towels/bath towels in it. Break out a towel, drap it over the barrel and receiver area for a minute or so to soak up the heat. Shoot until hot again and put the towel back on. Continue this until the towel no longer cools the barrel down quickly. Put that towel around my neck and get another from the cooler. Keep my ammo in the cooler with the frozen towels.

Looks goofy, but I've seen guys dunking their muzzles in a 5 gallon bucket of water and pistoning the water into the bore with a cleaning rod and patch to do the same thing. My method is neater and I get personal relief with the cool towel! :D

To answer your question, when you can't hold onto it, it's too hot. Stop shooting immediately until it's cool. Yes, cool. Heat will destroy that barrel. Nothing else will. Use two guns.

Yes, it does matter what you're shooting. While I don't believe bullet friction has much effect on barrel heating, the amount of powder in the charge definitely does. Every grain of powder has to burn to create the hot gas - the more powder, the more hot gas. The hot gas is in contact with your steel barrel, and transfers a significant amount of its heat to the steel, so the more powder that's burned, whether by few large shots or many small ones, the more the steel heats up.

I would disagree that fat barrels heat more slowly. It's steel - it heats exactly the same speed as thin barrels, it just has more mass and takes longer for you to feel it with your hand. It's in the inside of the bore and chamber that erosion takes place, however, and a thick barrel will be just as hot in there as a thin barrel. (Steel has a very poor ability to transfer heat - the reason your wife's kitchen pots have copper bottoms - so the thicker steel barrels really don't provide much protection from barrel erosion. Thick barrels do provide strength to resist heat stress induced warping, however.

So, let your barrels cool to at least where they're comfortable to hold in your hand. While they're cooling, rack the action open, barrel up (or down) rather than horizontal, so that natural heat rising will suck cooler air in the bottom and force the hotter out the top. Then, have a nice .22 to entertain you while you're waiting.

When in a hurry, I've used wet towells to speed the cooling process, but it horrifies people around me, so I don't do it much anymore.

Jaywalker

#1 thing, yes heat makes steel expand in every direction, thusly a hole will actually get smaller ie your bore and groove as it gets hotter. Then by all physics principles your pressures will get higher as you shoot the same load. This is the reason some guns will shoot better when the bbl is warm. To answer the question, pace your shots when doing target or load testing allow at least 3 mins between shots with a hunting rifle, and 10 mins between test loads. With this given, you should take at least two more guns with you, a .22 just to practice your offhand, shooting, your favorite deer rifle just to make sure you are honoring your quarry when you next hunt it. This practice will help you immensly during the hunting seasons, and give your bbl a chance to cool between groups.

... a hole will actually get smaller in your bore and groove as it gets hotter..
That turns out not to be the case - the hole gets bigger. It's one of the basic questions on engineering tests - they heat a ring and the ball which could not pass through it now suddenly can. The metal does try to expand inward, but the whole field is expanding outward faster. The proof is to figure the circumference of the two "rings," the inside of the barrel and the outside of the barrel, and what happens to the radius.

http://www.phys.washington.edu/facilities/lectdemo/thermo.html
Ball and Ring -- a metal ball and ring on handles are constructed so that the ball will just pass through the ring at room temperature. The ball is heated and will not pass through the ring. The ball and ring are both heated and the ball now passes through the heated ring.

Ball and Hole -- a ball which is too large to pass through a hole in a square metal plate will pass easily through the hole after the plate has been heated in a flame. Many students expect the hole to shrink upon heating, but it actually expands along with the rest of the plate.

Pressure does rise when shooting a hot barrel, but from temperature transfer to the powder inside the cartridge case, rather than constriction. Use of less temperature-sensitive powders, such as Hodgdon's Extreme powder line, minimizes this heat/pressure effect. It also helps with maintaining velocities and accuracy after working up a load in the summer, then hunting with it in the winter.

Jaywalker

Jaywalker, They do heat the whole ring? Not just the inside first? Them engineering students and their studies, are correct. I may be wrong, but the physical reaction is to push the hot against the cold outer, thusly making the inside smaller. When the heat transfers enough to make the whole bbl hot then it will get larger. In the mean time we are being driven nuts, as to why the groups we are shooting are going all over, and now we have another thing to worry about ha ha. This given the bullets do obturate to fit the bore whether oversized or not, but at different rates. Bottom line take several guns to the range and very slowly work on your load testing without the bbl heat to be in the equation. The more we learn about this the more confusion. Do take care and have fun. Swany

When the heat transfers enough to make the whole bbl hot then it will get larger.
Swany,

Interesting point. You're correct, the "hole getting bigger" does assume uniform heating, so I can understand why we might think the barrel has no place to go but in, when it first starts heating from the inside. It just seems that it can't do it, since atoms get farther apart when heated, and if the radius gets smaller, they'd be getting closer. I pass.

Jaywalker

Was it here or somewhere else that I read someone de-bunking the fluted barrel theories, is nothing sacred?

Evidently not, JB -

Have several with fluted barrels. Some may debunk them, but all I can say is - the next custom barrel I have installed will be fluted like the others. Seem to work well for me. Shooting several at a time, the fluted ones noticeably take longer to heat and cool faster than plain barrels.

To each his own.

I will try to find the link and post it here, I don't really have a preference one way or the other

Get a gallon can. put two holes in it just big enough for attatching rubber hoses, sized to fit in your chamber. Put dry ice in the can, See where this is going? Push air from the dry ice into the barrel slowly. It aint scientific, but it does work.

r

Slightly involved, isn't it?

When thinking of the fluted bbl, I often thought about using a round nose cutter and a say 4 turns per inch cut and see how much extra surface I could get for cooling purposes. Guess thats why the spiral flutes anyway. That way the bbl could double as a corkscrew in a pinch ha ha.

I have a question about getting a barrel to hot. I have been told not to get the barrel of my rifles to hot. If you can't put your hand on it comfortalby then the barrel is to hot. Is that about right?

Another question is what happens when the barrel gets to hot?

And does it make a differance on what rifle you are shooting. For instance a 22-250 or a 22lr or wiill it do the same damage with either?

I have heard there is a way to take the heat walk out of a barrel. Cryogenic cooling along with phased reheating. I mean realy cold. There are companies that will do this for you for about $100 if you send them a stripped barrel. I think some "accurized" custom rifles are treated this way by the manufacturers.

Yes, the cryo treating of metals is supposed to realign the grain structure and remove the stress of being machined. The barrels or bbl'd actions are dropped into liquid nitrogen to attain just about absolute zero, then slowly allowed to warm back to ambient temps. There's a place over in Scottsdale near me that does this. Haven't used their services, however.

This thread was concerning the cooling of rifle barrels during firing.

Seem to remember Layne Simpson having an article a few years back about canned coolant that was made for this purpose. A long tube was used to give a blast of CO2 down the bore - like using one of the CO2 fire extinguishers. Was sorta expensive as I recall, that's why I never gave it much thought.

Been out at the range with my black powder kit along with me. In it is one of those CO2 ball ejectors (for when you get the order wrong and put the ball down before the powder).

Just for fun, tried the CO2 ball remover on a hot centerfire rifle barrel....just plugged it into the muzzle (being careful not to damage the crown) and pulled the trigger.

CO2 did a fine job of cooling things down...and considering it was being cooled from the "hot side" it seemed to work very well.

SO...while at the computer store looking at geek-gear, noticed a little air squirter than looks a lot like the ball ejector. Was made for blwoing out key boards. Can easily be modified to run on CO2 cartridges (as is, is made to run an an ari cartidge that is about 1/4" longer)...and the little oriface enlarged... bought one, modified it to take CO2 cartridges, and opened her up so that you only get three or four good blast from a cartridge. Added on a length of larger diameter plastic tubing and a rubber washer made for bathroom faucets so that the crown won't get dinged. I just mash the beveled rubber washer onto the crown and pull the trigger...wait a bit...pull the trigger again.

Could get creative and run it from the chamber end...but this way is more "universal" and seems to work just fine.

BUT CO2 cylinders aren't all that cheap and it takes most of one cylinder to really cool a hot barrel.
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OH...if you ever get a case stuck in the chamber, the above is worth a try at getting it out.

I'd been thinking about a battery-powered air pump, like the kind aquariums use for oxygenating fish tanks during power outages. Rack the rifle, barrel up, and run an air tube from the pump to the action and into/near the chamber, duct tape it in place, and turn it on. More air flows than normal convection currents would allow - I expect it would cool the barrel three times as fast as normal. Not as fast as CO2, but it would be reusable.

Jaywalker

I'd been thinking about a battery-powered air pump, like the kind aquariums use for oxygenating fish tanks during power outages. Rack the rifle, barrel up, and run an air tube from the pump to the action and into/near the chamber, duct tape it in place, and turn it on. More air flows than normal convection currents would allow - I expect it would cool the barrel three times as fast as normal. Not as fast as CO2, but it would be reusable.

Jaywalker

Why so exotic? Just use a car vacuum cleaner and suck instead of blow:) I just bring another rifle or two.

Why so exotic? Just use a car vacuum cleaner and suck instead of blow:) I just bring another rifle or two.That sounds like it would work fine, if you're within electric cord range of your car. Might need a more elaborate mounting system, since it's heavier than a plastic tube, though.

Jaywalker

Some Military longarms have chrome lined barrels which not only help to fight corrosion but also provide a harder surface==more difficult to erode from heat.

I found this information on another forum.Buy a bottle of rubbing alcohol and bring a clean cloth with you to the range ,dampen the cloth with rubbing alcohol and wipe on the barrel after firing,it's supposed to cool it down.

I found this information on another forum.Buy a bottle of rubbing alcohol and bring a clean cloth with you to the range ,dampen the cloth with rubbing alcohol and wipe on the barrel after firing,it's supposed to cool it down.


When I ust to be in a hurry, would take a CO2 ball ejector (they sell them for muzzle loaders)...made a tapered plug to fit most breeches...gun got too hot, would give here a few squirts of CO2.

(Althugh i haven't tried it, suspect (if fitted to the muzzle) also eject a stuck case.)

Just a thought that crept into my head. I'd believe the heated ring would still be round. But, is the round hole in a square piece of metal still round when the metal is heated? If not, by the same token wouldn't the bore in a fluted barrel get out of round when heated due to the differing amounts of metal in the flute valleys vs. the full diameter of the barrel? If hot enough, obviously.

Just a thought that crept into my head. I'd believe the heated ring would still be round. But, is the round hole in a square piece of metal still round when the metal is heated? If not, by the same token wouldn't the bore in a fluted barrel get out of round when heated due to the differing amounts of metal in the flute valleys vs. the full diameter of the barrel? If hot enough, obviously.

Better use some bug killer to get the creepers. The barrel may get some deflection from the heat (no longer straight), but the bore is the same all around. The diameter might change, yet it would stay as round as it ever was.

There is a procedure (cryogenic cycling) that "equalizes" the barrel metal so it does not bend the barrel when it all gets hot.

Acually, I once had an H&K with a twisted eliptical bore, no rifling. The bullet got its spin from the elipse. This was essentially a machine gun barrel on a sport rifle.