Posted: 12/8/2014 8:51:12 PM EDT
| Is there any way to cool a 308 barrel after shooting it so it won't effect the accuracy? |
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Heat (& Pressure) kills barrels (wears out the throat), so you should avoid them at all costs if possible.
Not always possible, so what can you do? Buy a Quality Barrel - there are barrels that are properly heat treated / stress relieved that will not be as negatively impacted by the heating. Poor quality barrels are going to do all kinds of things that you do not want when heated. Add a Cooling Device - you can run something like the JP Rifles Thermal Dissipator http://www.jprifles.com/1.4.5_hs.php. There are also designs like the POF that incorporate an Oversized Heat Sink Barrel Nut http://www.pof-usa.com/pof-rifle-overview.html Physically Cool It - you can put wet towels on them, run a fan blowing across them, I have even seen water jacketed barrels. You just have to watch, because having a barrel going through multiple thermal cycles can do some weird things. Also "thermally shocking", meaning heating and cooling a barrel very rapidly, can actually cause damage to it. Two Schools of Thought: - Run a very Thick/Heavy Barrel Pro: they can handle more heat delaying the impact on performance/accuracy Con: once the heat is there, it takes longer to get it out, and keeping the heat there can have negative impacts on barrel life - Run a Thinner/Lighter Barrel Pro: they will allow the heat to escape quicker and the barrel will cool quicker Con: you have to limit/manage the heating, or deal with the impacts when it heats up Best of Luck, M Richardson |
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In the summer at the range when it is 95+ when I shoot say 100 rounds over a 2 hour period with some 20 shot strings over a couple minutes. I don't notice a loss in accuracy or POI change with my heavier profile barrel.
I don't worry about temp, I am there to shoot not wait for steel to cool. 4400 rounds and she isn't burn out yet and I can count on 1moa 10 shot groups. In my recent Forster seating die test with concentric ammo I had 11 or 12 7shot groups that averaged .686moa(factory 700 bbl'ed action) When I am shooting for absolute accuracy I do monitor barrel temp just to keep make sure I don't let it cool. The hottest I have seen is 130 at the chamber, 30-50 more toward the muzzle. But so far over a 30 degree range I am not seeing a difference with my heavier 20" bbl. My cold bore shots are on and my hot bore shot are on, so I am not worrying about the barrel temp. If you have a real light barrel then you may have an issue. I don't care that my barrel life will be a bit shorter , I like to shoot. I should add one very important thing, I never close the bolt on a round until I am set-up and ready to fire. If you chamber a round in a hot gun then fuck around for 30 seconds before sending it you will have problems because the ammo temp will be all over the place. Posted Via AR15.Com Mobile |
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A simple way is if you cant keep your hand on the barrel ( its too hot ) cool it down standing it upright, with action open or bolt out. Let the cooler air draw up the barrel from the chamber to the muzzel.
Think of it like this. If one was to place a bit of metal on the cement on a hot day. It will get hot very quick, now do it again but this time stand it up right and you'll fond the steel to be much much cooler then when it was placed on the ground flat in for the same time. Where i live 95-135f isnt uncommon for most of the year. Regards Skip |
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Seeing as how this thread is for bolt actions both of the good captain's
proposed cooling devices are not applicable, they are for AR pattern rifles. Water cooling jacket on a bolt action? Really? Placing a wet towel on a hot barrel will induce the worse kind of stress as it affects the metal by uneven cooling. Make a practice of this and you'll anneal areas of your barrel. Bad idea. Best idea is to let time take its course. The normal rate of cycle for a bolt action rifle, even timed and rapid, shouldn't be sufficient to damage your barrel. Will it get hot, absolutely, hot enough to cause damage, doubtful. Now full auto, that's something else entirely. Sooner or later you'll realize that the barrel is just another tool that will eventually wear out. Get used to the idea of re-barreling when you see your accuracy degrade and it stays that way. Ted |
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Quoted:
A simple way is if you cant keep your hand on the barrel ( its too hot ) cool it down standing it upright, with action open or bolt out. Let the cooler air draw up the barrel from the chamber to the muzzel. Think of it like this. If one was to place a bit of metal on the cement on a hot day. It will get hot very quick, now do it again but this time stand it up right and you'll fond the steel to be much much cooler then when it was placed on the ground flat in for the same time. Where i live 95-135f isnt uncommon for most of the year. Regards Skip EXCELLENT! Sage advice Skip! Ted |
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You could take an idea from the prairie dog shooters that shoot a lot in hot weather. They keep a cylinder of nitrogen and a hose with them and place the hose in the chamber and open the valve and let the cold nitrogen cool the barrel.
I've seen bench rest shooters do this also. |
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Quoted:
. . . . SEE ABOVE . . . . Ted The cooling devices that I posted were simply examples. Actually as long as your barrel diameter is the appropriate size, there is no reason that you couldn't put one of the JP models on a bolt rifle. I have seen bolt rifles with similar devices. Those aluminum cooling devices are actually more functional at cooling than fluting a barrel. There are water jacketed designs used in certain applications, primarily Benchrest, but I have also seen them used on F-Open rifles. Per my original comments, placing a cold towel on a hot barrel thermally shocking it, is a bad idea. Using a wet towel evenly wrapped around the barrel to slow the heating process is a practice used in some applications. Shooting applications rule & dictate what is reality. Things that would be asinine for an average shooter, are the norm for some forms of shooting. Rates of fire may be up to an average shooter, but they may also be dictated in many forms of shooting. Using a .300 WM, an average shooter/hunter with a lax firing schedule could get 1,500+ rounds out of a barrel, where a competitive shooter routinely firing rapid strings could burn out a barrel in less than 1,000 rounds. There are examples where an excessive firing schedule with an overbore round in a bolt rifle had damaged a barrel to the point of being marginally serviceable in as few as 500 rounds. The US Army Sniper School has learned a lot of this the hard way over the last couple of years with the introduction of the M2010 in .300 WM, versus what they had been used to with the M24 in .308 Win. This has also been documented in a competitive shooting like F-Class. Yes barrels have a finite life, how finite can be dictated by how they are used. Best of Luck, M Richardson |
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Quoted:
. . . . . SEE ABOVE . . . . While there is obviously value to this, be careful if you are utilizing a public range. Per firearms safety rules, many ranges require that a rifle remain pointed down range in a safe direction at all times. I know of plenty ranges where if you pointed a rifle up in the air and set it down, that you would have a RSO in your case immediately! Thanks, M Richardson |
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Quoted:
. . . . SEE ABOVE . . . Posted Via AR15.Com Mobile Per my comments in the response above, it comes down to what you are shooting, and how you are shooting it? You could fire something like a typical .308 that may be producing something in the area of 50,000 PSI at a leisurely pace and see a serviceable barrel life of over 5,000 rounds, versus firing an Overbore round at 60,000+ PSI at a rapid pace and see a barrel life that is less than 1,000 rounds. Pressure & Heat destroy barrels (along with other things) Practical Tips To Extend Barrel Life Can you "externally" cool a barrel to offset the internal temperatures to a point where it will have a significant impact, not under most normal shooting situations/circumstances. Thanks! M Richardson |