Letting Barrels cool down - is there a standard routine you follow?

[jacobhh]

Barrel heat is a variable as is barrel fouling, both will effect accuracy to
some extent. Excessive heat swings ( ie. 4" ) may indicate a problem on
your bolt guns, such as a tight stock or metal bearing on the barrel.

Improper/aggressive cleaning is the quickest way to lose accuracy. This is
especially true of the M1A's muzzle. But you must keep the M1A's chamber
clean for safety.

I also start low reloading and try to keep loads as light as possible
for acceptable accuracy. That's the point at which my shooting, or
reloading technique is the primary accuracy constraint. A hunter will
likely have different concerns.

I always fire a 'fouling' shot, only load and fire five at a time, walk down
and check/change my target every ten and run a couple of patches after
twenty. I don't claim this is the best way, it's just my way.

 

[pilot teacher]

Experimented at the range today with my Savage 10 .243
In cold wx, can shoot about 15 rounds w/o groups opening up.
Today temps +92 here in central FL. The first 3 went into 3/4 inch. then opened up to 1.7" After cool down, groups again 3/4 to 1". After 3 shots about 1 min. aprt, groups opened up even more than before. May replace barrel with a heavy Adams and Bennett target configuration like I did with my 03. Very happy with that.
Spent a day in the sweat and fired only 30 rounds before stopping the waste of powder and bullets. Would do no good hunting PD's in hot wx.

 

[Slamfire]

On very cold days, after shooting rapid fires, I have wrapped my poor cold hands around my rifle barrels to get a little bit of heat.

On something like a service rifle with all that wood hanging on the barrel, those things will walk as they heat up. So have my featherweight M70's. Lightweight barrels are the worst in terms of moving when hot.

I think a lot of old barrels were "straightened" at the factory, which means they have internal stresses. Heating them just creates strange movements.

Of course shooting things like Rattle Battle will eat up a barrel throat, but even though I have fired close to 40 rounds in 50 seconds in Rattle Battle, my zeros are unaffected.

* Used to hear that the smaller the caliber (centerfire) the longer the wait between shots. Ditto the shorter the barrel. Have no idea if that is valid.

This is what happens when people skip heat transfer. They come up with some wierd correlations.

 

[goon]

It's largely dependent on the barrel more than how old the rifle is.
Heavier barrels are more rigid and dissipate heat better so they stay more accurate for more rounds.
Thinner barrels are less rigid so they can flex more as they heat up.
I had a Savage scout that would put the first two rounds touching at 100 yards. The third shot was about an inch higher, and the fourth was 4" above that. By the fifth shot it was nearly off the paper.
I never had that problem with the M-39 I had. I've also not noticed it with any of the FAL's I've owned - they all seem to shoot about the same sized groups no matter how fast you shoot or whether or not they are allowed to cool between shots or strings.
On the fouling shot, with some guns it's a necessity. My dad's 99 Savage won't shoot from a clean barrel. If you want to hit anything with it, it's gotta have a minimum of two or three shots down the bore. His standard routine is to go out after thanksgiving dinner and fire his fouling shots until he is sure the rifle is hitting where the crosshairs are. None of the rifles I've owned seemed to care one way or the other though.

I guess it can be hard to make generalizations sometimes.

 

[RaspberrySurprise]

If the hand guards ever burst into flames I'll stop. I have a WASR-10, SKS, and two Mosins so I expect them to take it.

 

[LAK]

I don't worry about .22s heating up. I'll let a centerfire pistol or revolver cool off if I should a couple of mags or cylinders quickly.

Rifles get a cooling off if they involve a twenty or thirty rounder emptied quickly. Bolt guns generally shoot two-shot groups and I let them cool alittle between shooting.

 

[borntwice]

Yeah, if the barrel burns my finger, I try to keep my finger off it. That's my standard procedure.

 

[geim druth]

I watched a movie called 'Wild Times' last night. A pretty good one as a matter of fact.

But, one of the characters did something that really surprised me. During a long shooting competition he kept dunking his rifle barrel in a cask of water to cool it down. An older shooter specifically tells him that this won't hurt his rifle.

I've never heard of such a thing, is this just Hollywood or is it for real?

 

[Horsemany]

I think a lot of old barrels were "straightened" at the factory, which means they have internal stresses. Heating them just creates strange movements.

I saw a TV show about 2 years ago where they toured the Savage factory. There's an old guy there who does nothing but straighten the already made barrels. He had a fixture that held the barrel up about 45 deg. He had a light at the other end. They said he could look down the bore and see shadows. Then he rotated the barrel where he needed it and used a special bar to slightly bend (straighten) the barrel. It was all done by a well trained eye. I do not see this act of straightening to be a negative since almost no gun mfg. can make a barrel that shoots as good as a Savage IMO.

I'm not saying you're wrong about the internal stresses. I just thought I'd point out some of the best barrels made today are built this way. Perhaps the barrels who need the most tweaking or bending will be the ones that shift more when they heat up.

 

[USSR]

I do not see this act of straightening to be a negative since almost no gun mfg. can make a barrel that shoots as good as a Savage IMO.

I'm not saying you're wrong about the internal stresses. I just thought I'd point out some of the best barrels made today are built this way.

Where do I start? First, SlamFire1 is indeed correct about the stress that is induced by "straightening" a barrel, and it's impact as a barrel heats up. Second, while Savage barrels are good, there are plenty of barrels made that will shoot as well or better than theirs. Lastly, the best barrels made today, yesterday, and in the future DO NOT involve straightening the barrel. The best barrels made are drilled properly and require no straightening.

Don

 

[Art Eatman]

Don, the unknown factor in that barrel-straightening is whether or not the barrels then were run through the stress-relief oven. That's easy enough. (More of a hassle when the item is a tube-frame race car chassis. Big, expensive oven. )

 

[Slamfire]

Used to hear that the smaller the caliber (centerfire) the longer the wait between shots. Ditto the shorter the barrel. Have no idea if that is valid.

I was thinking of how could someone come up with this idea.Then I thought, on the same barrel contour, a smaller caliber would leave more metal in the tube. So I think whoever came up with this thinks that with the greater barrel mass, the heavier barrel would take longer to cool.

Which could be if the heat inputs were the same. But since smaller cartridges (except for things like the 22/375H&H) tend to have less powder, they produce less heat input.

Heat transfers faster, the greater the difference between hot and cold. Metal also transfers heat within its self exceptionally well, so for a barrel, the limiting factor should be the transfer of heat to air.

Which may be the thought on the idea that longer barrels will cool down faster than shorter barrels. More surface area.

That would be an interesting calculation to make, since this is a non steady heat transfer problem, is there a significant time difference in reaching room temperature between a .22 barrel and a larger caliber (lets say 30 cal?, how about 45 cal?), assuming same exterior contours and same starting barrel temps?

 

[USSR]

Art,

Since we are talking about the way

some of the best barrels made today are built

I will only say that the two barrels I had made by arguably the two best barrelmakers in the country (Boots Obermeyer and Jack Krieger), were not straightened or stress relieved. When these guys have an "oops" moment, it goes in the scrap bin. To say that straightening and then stress relieving is de rigueur in quality barrelmaking is rediculous.

Don

 

[mndfusion]

The M39 has a full length handguard. I'd bet that the warm barrel is flexing and putting pressure on the wood, thereby changing barrel harmonics in a negative way.

M39 barrels are free floated....the stock's brl hole is larger than the brl -- but some m39 brls do have minor contact with the bottom part of the stock where it exits the stock.