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What kills barrel life on bigger magnums?

 
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  #15  
Old 12-16-2013, 05:02 AM
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Re: What kills barrel life on bigger magnums?

When fiftydriver speaks I tend to listen. Hard to argue with somebody who does this everyday.
Not too many years ago I was heavily into Title II stuff and you could burn out a barrel throat in a few minutes of pouring ammo through a machinegun. If you loaded up about 500rnds in mags and fed them one after another the barrel would glow. After cleaning it up an inspection of the throat showed it was shot out for anything other than ventilating hillsides and barns. Provided the barn wasn't too far away.

I've known about heating up a barrel for quite some time but there wasn't much you could do but wait it out. No fun just to sit still at the bench. Read about a wand hooked to a CO2 tank and blown through the barrel but it was so fast I wonder if it shocks the barrel, i.e. quenches it.
What kills barrel life on bigger magnums?-picture-21.jpg

This is a barrel cooler my son and I built. Scrap PC fans @ $1 each (3) and a 12 volt gel cell from a computer UPS backup also sold @ the box stores for alarm systems for $25 new. The big hose is a dishwasher hose, same source. The small hose is scrap from the garage and fits the bolt size pretty close (about 5/8"). Two of the fans are stacked and feed the forward chamber. The third fan forms the third stage and pushed the pressurized air from that chamber into the hose. You need to build some pressure not just volume because your going to push the air down a rifle bore, hence the three stages.
It sits on the ground under the bench and we open the bolt to extract the fired round and push the small tube into the chamber and flick the switch. With 45 seconds of run time we keep a barrel that starts at 85F under 100F for five shots. This is for something like a 300 WinMag or 375 Ruger. There is a K type bead thermometer taped to the barrel over the chamber to track it. The air is filtered by a piece of 3M Scotchbrite pad cut to fit the back of the box.

You can watch the temp fall when you turn on the switch. Keeps the barrels cool and our investment in the guns from heading toward the target in the form of vaporized steel. It lets us test a lot more ammo in the course of a day at the range so it has paid for itself in that alone.

Some people may laugh... but I've got one and they don't!

KB
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  #16  
Old 12-16-2013, 06:04 AM
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Re: What kills barrel life on bigger magnums?

Quote:
Originally Posted by bigngreen View Post
Using the trigger as a giggle switch repeatedly! A couple shots then checking conditions and letting things chill will go a long ways!
Lmao well,said sir well said as other said keep it cool and it will last a long long time, also just because your throat starts to error does not mean the barrel,is cooked it means you need to adjust your load.
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  #17  
Old 12-16-2013, 07:32 AM
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Re: What kills barrel life on bigger magnums?

Without getting too scientific the numerous barrels that I have gone through appear to definitely be effected by heat typically caused by rate of fire. My competition rifles that are used in the summer months with strings as high as 30 shot strings at 30 second intervals have half the life of those shot with cooling allowed between shots. Life is measured by accuracy fall off , from .25-.5MOA to .5 to.75MOA. generally, my 308 competition rifles see this fall off at 2200-2400 rounds. Throats erode .060-.120" with a R5 Milpec barrel, that is generally cleaned every 150-200 rounds. Shooting magnums at +3000FPS and the 6.5x284, accuracy seems to fall off at 800-1200 rounds. The low end, or worse for the Weatherby, Short mags, and other overbore designs, high end for the 7mm-300 standards. This is with cooling allowed between shots. Generally, heavier, lower velocity bullets seem to give better barrel life out of the magnums than high velocity, lighter bullets. Barrel quality also pushes life to one end or the other of the range. I'm sure some see better or worse life than I do. Overall, I think barrel life is a function of case/cartridge design, powder charge, shooting style/heat, barrel quality and cleaning procedure. I do keep a round count for all my rifles but generally don't get too hung up on barrel life with hunting rifles if the rifle performs well. For competition rifles, I don't want to have to change a barrel or rifle in the middle of the season. IMO.
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  #18  
Old 12-16-2013, 09:14 AM
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Re: What kills barrel life on bigger magnums?

Quote:
Originally Posted by Kennibear View Post
When fiftydriver speaks I tend to listen. Hard to argue with somebody who does this everyday.
Not too many years ago I was heavily into Title II stuff and you could burn out a barrel throat in a few minutes of pouring ammo through a machinegun. If you loaded up about 500rnds in mags and fed them one after another the barrel would glow. After cleaning it up an inspection of the throat showed it was shot out for anything other than ventilating hillsides and barns. Provided the barn wasn't too far away.

I've known about heating up a barrel for quite some time but there wasn't much you could do but wait it out. No fun just to sit still at the bench. Read about a wand hooked to a CO2 tank and blown through the barrel but it was so fast I wonder if it shocks the barrel, i.e. quenches it.
Attachment 29092

This is a barrel cooler my son and I built. Scrap PC fans @ $1 each (3) and a 12 volt gel cell from a computer UPS backup also sold @ the box stores for alarm systems for $25 new. The big hose is a dishwasher hose, same source. The small hose is scrap from the garage and fits the bolt size pretty close (about 5/8"). Two of the fans are stacked and feed the forward chamber. The third fan forms the third stage and pushed the pressurized air from that chamber into the hose. You need to build some pressure not just volume because your going to push the air down a rifle bore, hence the three stages.
It sits on the ground under the bench and we open the bolt to extract the fired round and push the small tube into the chamber and flick the switch. With 45 seconds of run time we keep a barrel that starts at 85F under 100F for five shots. This is for something like a 300 WinMag or 375 Ruger. There is a K type bead thermometer taped to the barrel over the chamber to track it. The air is filtered by a piece of 3M Scotchbrite pad cut to fit the back of the box.

You can watch the temp fall when you turn on the switch. Keeps the barrels cool and our investment in the guns from heading toward the target in the form of vaporized steel. It lets us test a lot more ammo in the course of a day at the range so it has paid for itself in that alone.

Some people may laugh... but I've got one and they don't!

KB
Most impressive setup!!! I have always been a bit nervous about the fast barrel coolers out there as well. Just do not like thermo shocking metal. Just not a good idea in my mind.

Congrats on the creative solution!!!
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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  #19  
Old 12-16-2013, 09:17 AM
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Re: What kills barrel life on bigger magnums?

Quote:
Originally Posted by Greyfox View Post
Without getting too scientific the numerous barrels that I have gone through appear to definitely be effected by heat typically caused by rate of fire. My competition rifles that are used in the summer months with strings as high as 30 shot strings at 30 second intervals have half the life of those shot with cooling allowed between shots. Life is measured by accuracy fall off , from .25-.5MOA to .5 to.75MOA. generally, my 308 competition rifles see this fall off at 2200-2400 rounds. Throats erode .060-.120" with a R5 Milpec barrel, that is generally cleaned every 150-200 rounds. Shooting magnums at +3000FPS and the 6.5x284, accuracy seems to fall off at 800-1200 rounds. The low end, or worse for the Weatherby, Short mags, and other overbore designs, high end for the 7mm-300 standards. This is with cooling allowed between shots. Generally, heavier, lower velocity bullets seem to give better barrel life out of the magnums than high velocity, lighter bullets. Barrel quality also pushes life to one end or the other of the range. I'm sure some see better or worse life than I do. Overall, I think barrel life is a function of case/cartridge design, powder charge, shooting style/heat, barrel quality and cleaning procedure. I do keep a round count for all my rifles but generally don't get too hung up on barrel life with hunting rifles if the rifle performs well. For competition rifles, I don't want to have to change a barrel or rifle in the middle of the season. IMO.
I would agree that the lower velocity rounds do seem to offer longer barrel life but again, it has more to do with actual bore temps then anything else.

Slower rounds tend to use powders that generally burn mostly in the case compared to lower expansion ratio designs where a significant amount of the powder charge is burnt in the throat and first portion of the barrel. When this happens, it simply takes longer for the bore temp to cool off.

Have tested different neck length designs, shoulder angle designs and I have never seen any of these make any real difference to throat life if the barrel was kept cool.
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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  #20  
Old 12-16-2013, 09:27 AM
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Re: What kills barrel life on bigger magnums?

One test I did many years ago that pretty much solidified my opinion on what keeps a barrel shooting well is when I tested some forward ignition systems in some of my wildcat chamberings.

Not to get to detailed, forward ignition systems use a brass tube connected to the flashole in some manner that carries the primer flame to a position in the powder charge just under the base of the seated bullet. When the primer is ignited, the hot primer gases ignite the powder just behind the base of the bullet and the powder burns progressively from the front of the case to the rear.

When you fire a case in a modern rifle, the ejected cases are hot at first but not DRAMATICALLY so and the first 1/3 of the barrel heats up quickly.

With forward ignition being used, the ejected cases are NOTICABLY hotter then conventionally ignited cases but the bore simply does not heat up early as fast. Why, because the only thing going through the case neck is gas, no burning powder. As such, with nearly 100% of all the powder charge burning INSIDE the cartridge case, the case insulates the bore from the heat generated and the bore stays very cool.

One test was with my 7mm Allen Magnum. In a sporter weight rifle, with conventional ignition, three rounds and the barrel was to hot to hold with a bare hand for more then a few seconds. With forward ignition, you could shoot 9 shots before the barrel temp reached the same temp as with conventional ignition systems.

Barrel life also increased dramatically, 2-3 fold!!!

You do have to change what powders you use for a given chambering because you are no longer PUSHING the weight of the powder charge and pushing ONLY the bullet weight. As such, you need to go to a slightly faster burning powder. In the end however, this system frees up pressure dramatically, again because your not pushing the powder charge throught the throat and in most tests, 100-150 fps performance increase was realized with same chamber pressure.

With all these advantages however, its a PITA to fit each case with a flash tube and there is always a chance the flash tube could come loose and go down the bore. This is a liability issue I just could not live with so I stopped this testing until I figure out a better design that positively locks the flashtube in the case 100% of the time.

It did however prove that bore temp was dramatically reduced and as such, barrel life exploded!!! Did not seem to matter what powder was used, ball, stick, it all showed similar results in the end. Also did not really matter what the case capacity was, in fact, the larger the case capacity was, the larger the difference in barrel life between conventional and forward ignition.

Was really amazing results, just need to figure out the reliability of the system to bring it to the market.
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Kirby Allen(50)

Allen Precision Shooting
Home of the Allen Magnum, Allen Xpress and Allen Tactical Wildcats and the Painkiller Muzzle brakes.

Farther, Faster and Flatter then ever before.

Web Page: www.apsrifles.com

allenmagnum@gmail.com
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  #21  
Old 12-16-2013, 01:46 PM
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Join Date: Oct 2013
Posts: 64
Re: What kills barrel life on bigger magnums?

I gave thought to using a small rag of some sort, soaked with light oil,
and kept in a chilled picnic basket. After each firing or two, just lay the
chilled rag on the barrel to wick some heat out. I figured the rag would
not be cold enough to alter the metal's temper, but by the same token,
not work lightning fast either in removing heat.
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