I know the obvious, like pulling the trigger but what is the main cause of barrel wear and how can it be minimised?
I have read posts from the more experienced amongst you and it seems one caliber will chew out barrels quicker than another even though there is little difference ballisticaly between the two.
Is it related to powder burn rates or temperatures, excessive powder residue acting like sandpaper as the next shot is fired, chamber pressure, barrel twist rates, all of the above or am I way off the track?
Boof.
Posts: 90 | Location: Sydney Australia | Registered: 04 July 2003
quote:Originally posted by Boofhead: I know the obvious, like pulling the trigger but what is the main cause of barrel wear and how can it be minimised?
I have read posts from the more experienced amongst you and it seems one caliber will chew out barrels quicker than another even though there is little difference ballisticaly between the two.
Is it related to powder burn rates or temperatures, excessive powder residue acting like sandpaper as the next shot is fired, chamber pressure, barrel twist rates, all of the above or am I way off the track?
Boof.
.....It sems to be a combonation of things given the barrel is the same material and quality...the amount of powder for the bore size....the bearing surface of the type bullet, the heat generated by the large amount of powder and it is increased by fast pace firing of the rounds and heating the barrel .....faster twist rates with fast cartridges cause the bullet spin to have to increase faster from the still coming out of the case and that causes heat and some stripping causing friction and more heat and increasing the wear at the throat ...the lack of cleaning can cause some increase in a very dirty powder/large size high pressure shell...and the high pressure of a high performance cartridge with a shoulder can cause all the things to happen and at a faster rate.....the large bore straight cartridges are seldom thought of as "barrel burners" ......this is from reading and feedback from fellow shooters and limited experience with a few barrel burners of my own....HTH..good luck and good shooting!!
Posts: 687 | Location: Jackson/Tenn/Madison | Registered: 07 March 2001
Quickest way to wear out a barrel is not allowing adequate cooling between shots. I have seen a uncareful shooter wear out a 220 Swift in a few months, I on the other hand shoot a .22-243 with about 1000 rounds down the tube with out any signs of wear. But that is for varmint rifles, where you can shoot all day, for hunting rifles I don't think being overbore will really be a cause for concern because you just aren't shooting frequently enough as long as you are careful when practicing at the range.
Posts: 593 | Location: My computer. | Registered: 28 November 2001
Correct me if I am wrong, when I was in basic training the Military theystated that rifles of the 30 caliber class would maintain accuracy thru 10,000 rounds. The faster magnum would be less also the type of bullets made a difference ie: high sectional densities and harder materials would be harder on barrels
Posts: 2300 | Location: Monee, Ill. USA | Registered: 11 April 2001
The 22-243 is based on the 243, which is in turn based on the 308. The 22-250 is based on the 250 Savage, which is based on the 300 Savage. The 22-250 is .133 shorter than the 22-243. The fastest I have ever launched a 55grn in the 22-250 is 3650fps, I have launched the same bullet 4170fps out of my .22-243, which is 400fps than the fastest 22-250 load Hodgon lists. So as you can see from the data, the .22-243 can burn out a barrel in no time.
[ 08-08-2003, 05:41: Message edited by: DanD ]
Posts: 593 | Location: My computer. | Registered: 28 November 2001
Hot loads fired in rapid succession will do it every time. I've seen M60 machinegun barrels get RED hot, literally. Under sustained fire the barells will actually droop to a certain degree. I LOVED the smell of napalm at dawn. Semper Fidelis.
Posts: 8169 | Location: humboldt | Registered: 10 April 2002
Sorta like this, Craigster? My dad's friend was telling me about a similar experience, he said you could actually see the barrel swell each time it fired a round.
Posts: 593 | Location: My computer. | Registered: 28 November 2001
All the causes mentioned by those responding are quite correct. Basically, a barrel does NOT WEAR out, it is ruined by high-pressure, extremely hot gasses that act like an acetylene torch, actually melting and carrying away a little of the barrel's steel each time it is fired. Naturally, the more hot gasses there are, and the higher the pressure developed, the more gas cutting and erosion there will be. (Read: large cases, lots of powder!) The hotter a barrel is the next time it is fired, the less heat rise is necessary to begin the melting process. So if you use smaller capacity cases developing lower velocities and pressures, and let the heat dissipate before firing the next shot, the longer your barrel will last.
Jim Carmichael's book has the greatest explaination on why barrels go bad. If this brillant man won't mind, I'll try to remember what he said on this problem.
Steel is a blend of different materials, chrome, molybdenum, carbon, nickle,etc. No matter how well blended, there are "islands" of each element. When the cartridge is fired the gunpowder is hottest at the case mouth. The duration of the "flame" and the surface area affected by the heat, burns the carbon out leaving "islands" of chrome, nickle, etc., which gives the frosted or rough look to the throat of the barrel. This erosion contributes to further flame cutting because of an inadequate seal at the base of the bullet.
I believe in Hatcher's Notebook, he tested a barrel to see if the friction of a bullet would wear out a barrel. He check the muzzle where the bullet would be going the fastest. The short of it was, bullets don't wear out barrels. Improper cleaning, no cleaning, and throat erosion is the reason barrels go bad. Hope this helps.
Posts: 426 | Location: Nevada | Registered: 14 July 2003
quote:Originally posted by eldeguello: All the causes mentioned by those responding are quite correct. Basically, a barrel does NOT WEAR out, it is ruined by high-pressure, extremely hot gasses that act like an acetylene torch, actually melting and carrying away a little of the barrel's steel each time it is fired. Naturally, the more hot gasses there are, and the higher the pressure developed, the more gas cutting and erosion there will be. (Read: large cases, lots of powder!) The hotter a barrel is the next time it is fired, the less heat rise is necessary to begin the melting process. So if you use smaller capacity cases developing lower velocities and pressures, and let the heat dissipate before firing the next shot, the longer your barrel will last.
Or, BIGGER cases developing lower pressures, not necessarily lower velocities! It's the heat from the pressure, not the friction of the bullet. It doesn't matter, within ordinary parameters, how fast the bullet goes, but how much pressure (and its heat) it takes to get it going that fast. The 35 Whelen is often loaded to max peak pressures to get the kind of performance they want on the hunt, but I bet you there are lots of 338 RUM's out there being loaded at "moderate" levels, which are insanely fast, BTW.
Posts: 2000 | Location: Beaverton OR | Registered: 19 December 2002
Heat and friction are the most common culprits. One reason that I like heavy for caliber bullets in fast shooters is to slow the load down a bit and go a little easier on the bbl. The benefits of a larger bullet ballisticly are equally tangible, so in a sense you get the best of both worlds that way.
Posts: 10174 | Location: Tooele, Ut | Registered: 27 September 2001
If it is heat and bad cleaning techniques that does in the barrel, then I must jump in here with some questions for the board.
I was at the range yesterday developing some loads for my 30-06 and I would fire 5 shots in a rapid manner. In only 5 shots the barrel was pretty hot. My loads were loads were as follows:
Sierra 125g. Pro-Hunters, IMR 4895 47-54g. in Win. Super X cases. CCI 200 primers.
Rem 150g. Bronze points IMR 4895 47-51.5 in FA 60 Match cases, CCI 200 primers.
How hot is too hot? Is 5 shots enough to worry about? This is a my deer/elk/black bear rifle with a pencil thin barrel. After the 5 rapid shots for groups I would shoot my .22 untill the 06 cooled off, usually 10-15 minutes between strings.
My other questions center around the use of a bore guide. Since I dont have a bore guide yet should I just use my Bore Snake instead of risking harming my barrel with only cleaning rods? I have two rods, one is stainless and the other is a coated one, is the coated one better? I have a stainless spiral shaped bore brush should I use this or a bronze or nylon brush?
Thanks, Redrider.
Posts: 82 | Location: seattle | Registered: 14 January 2003
When I'm sighting in or shooting for groups, I fire one round every 60 seconds. How hot is too hot? In competition you will fire 10 rounds in 50 or 60 seconds, but that's it. That and prarrie dog shooting is the only rapid fire I shoot any more. Big game hunting, maybe 2-3 rounds at the most and I don't think I'll ever wear a barrel out. If it burns your hand, then it's too hot! I once fired approximately 1100 rounds thru an M16E1 without cleaning it and almost all was fired semi auto. No malfunctions and it took me a half a day to clean it the next morning. After 13 months and untold thousands of rounds the rifle would still shoot a quarter size group a 50 meters. The only barrel I have ever replaced was a .45 acp barrel after 42,000 rounds and the pistol would still out shoot me! I just got offered a free barrel.
As for bore guides, what ever did we do before we had them? Just take it easy and center up your rod until you can get one. I use snakes only for a quickie cleaning to knock out the fouling between groups.
Posts: 426 | Location: Nevada | Registered: 14 July 2003
Barrels are eroded by high pressure loads of slow burning powder, particularly in overbored cartriges.
"Hot" when applied to rifle barrels does not mean warm or hot to the touch. If the barrel will actually burn you then it is too hot.
Sometime ago I put a 200 degree Tempilstik in my shooting box just for shooting buddies that are anal about "hot" barrels. Now they don't hold me up waiting 20 minutes to fire 5 rounds
Wally
Posts: 472 | Location: Oregon | Registered: 08 March 2002
It's pressure. Steel does not vaporise at the temps. generated by gunpowder. If you've ever seen a pressure curve taken with an Ohler PBL or other lab equipment AND seen the interior of a barrel that has been fired a sufficiently to generate wear, you'll see the correlation.
HIGHER pressure rounds accelerate this process. All barrels suffer to some degree. The pressure causes the barrel to swell very slightly where the pressure is greatest, in the first few inches. As they swell, they crack. You HAVE seen the alligator hide look of a well worn throat, right? After they crack, chemical residue from the powder is deposited and corrosion begins. It is a relatively slow process, but quite relentless. It is said that this process can actually DECREASE the bore size slightly forward of the throat in time, a circumstance that can be improved by lapping.
The burning gas behind the bullet is what causes barrel wear,it it well above the melting point of steel,luckily it only has a small fraction of a second to cause wear & only removes a minute layer of metal every time.
The more powder used for a given bore size, the more wear that will take place.
I like the explanation in the back of the sierra reloading manual "Putting it simply,a barrel is washed out by "x" pounds of powder,Whether it's spread out over many small charges or a small number of large charges,it's still "x" pounds of powder.For example,a 308 winchester will have longer accuracy life than a 300 Weatherby Magnum,simply becauses it uses less powder per shot".
Posts: 318 | Location: Australia | Registered: 24 November 2002
Have you ever touched the metal output line of an air compressor, they tend to resemble a fully automatic rifle bbl that just emptied its magazine. HOT is the word and pressure is the cause. The same thing happens with turbochargers, the boost pressure dramaticly increases input air tempratures, thus the need for intercoolers.
If a bbl never got hot it would last an infentesimal amount of time, when the heat reaches a certian point they become much more suceptable to damage. Thats why moly will extend barrel life, its not unlike the thin layer of motor oil that keeps engine bearings intact. And when they loose that oil, first they heat up and then they fall to pieces in a big hurry.
I would be very interested in any barrel wear data that anyone might have reguarding the water cooled barrels used in WWII machine guns.
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Semper Fidelis.
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