polishing a barrel?

S

skeetlee

Active member
Will polishing a chambered barrel on a polishing wheel ruin the barrel? What i am asking is, will the heat from the polishing wheel cause any damage to the steel as far as stress is concerned? The polishing wheel can cause the metal to get fairy hot. Is this a bad idea? I dont want to polish anything and find out later that i ruined a barrel. Lee
 
I don't believe it could get hot enough to change the temper, and that would be the main issue.

If it gets too hot to hold, polish more gently...........
 
That's what i wondered Roy. I have polished butt plates and other items including an action one time and the items can get a bit to hot to hold. I read a post in the archives here thus bringing this question to mind. I know nothing about steel, and its properties, so i thought i ask. thanks man!! Lee
 
With a polishing wheel you are not going to get a proper heat treated barrel to "change the temper" (this would be above 1200F) but you could possibly get a spot, locally, hot enough to induce stress. This would be an extreme and your buffing wheel would be on fire if you used enough pressure like in trying to buff out a ding or occlusion. After all a rifle barrel is a pretty big heat sink.

http://www.speedymetals.com/information/Material50.html#Heat Treating

Over the years a few people have gotten hurt by "spinning" a barrel between centers made of wood or plastic and the center gives way while the barrel is spinning very fast. This is where they were spinning the barrel with something like a belt sander or buffing wheel.
 
One Reason Not To Polish

TB on polishing competition barrels.

"I do not want my barrels polished or have patterns put on them. The way they come out of the lathe is fine by me. Polished barrels take longer to cool between rounds. A rough surface provides more surface area so the barrel cools faster."

Source; The Book Of Rifle Accuracy P. 196
 
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I don't think you could get it hot enough by buffing to harm anything other than your hands...

...and a barrel painted flat black will cool off faster than one not painted...
 
Not that I know of... but it is easily touched up...
 
do you really think the cooling time differences is significant that one would really even notice??? I really wonder/ Thanks fellas!! Lee
 
I don't think the cooling times are significantly different between a polished barrel or rough turned or painted...
 
Remember the FAD - - -

where folks were running coolant through they barrels after each match? Haven't seen anyone doing that in a few years - - - -
 
Dennis Sorensen said:
I don't think you could get it hot enough by buffing to harm anything other than your hands...

...and a barrel painted flat black will cool off faster than one not painted...
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Dennis- I'd like to know where I can find info to support this claim. I used to work in Cryogenics and recall that a black body will absorb radiation at a greater rate than a reflective one.....a term called "emissivity" . The emissivity value for polished steel is ten times greater than iron painted black. I believe the difference will be very small at any rate to the point of being negligiable in what we do in competition.
 
LHSmith said:
Dennis- I'd like to know where I can find info to support this claim. I used to work in Cryogenics and recall that a black body will absorb radiation at a greater rate than a reflective one.....a term called "emissivity" . The emissivity value for polished steel is ten times greater than iron painted black. I believe the difference will be very small at any rate to the point of being negligiable in what we do in competition.
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Back in the late 60's snowmobile racers found if they painted the heads flat black they ran way cooler than not painted. This was proven by temperature gauges on the engines. I raced a bit for a couple of years and remembered that tidbit.

I seriously doubt if it would make any difference in the shooting sports. I have the same doubt with an unpolished barrel making any difference.

(A Black Body Emitter (BBE) heat radiating coating applied to the outside of the cylinder and head, will help dissipate any heat that does get through the TBC and is particularly effective on hot-running fan cooled engines.) : http://www.swaintech.com/store.asp?pid=10314

.
 
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Not at all...I just think that it might be interesting to do some testing. It may be that this sort of thing is not of much consequence for short range Benchrest, but it might be very beneficial for those who shoot rapid 10 shot strings in 1,000 yd. matches, and for any other type of shooting where barrel heat can be an issue. I do remember that someone once told me that in hot weather that he seemed to get better results cooling his barrel with a cold wet rag between matches. Sometimes low tech is the best.
 
Boyd Allen said:
Not at all...I just think that it might be interesting to do some testing. It may be that this sort of thing is not of much consequence for short range Benchrest, but it might be very beneficial for those who shoot rapid 10 shot strings in 1,000 yd. matches, and for any other type of shooting where barrel heat can be an issue. I do remember that someone once told me that in hot weather that he seemed to get better results cooling his barrel with a cold wet rag between matches. Sometimes low tech is the best.
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Up here in Michigan we don't get that much Hot weather to shoot in, but we do get plenty of the cool weather. Once my barrel is warmed and working well in cold weather either I finish my string (group or score) or i fire a shot now and then on record just to keep the barrel warmed up. Barrel heat works both ways.

Paul
 
I can tell you this.........A flat black barrel sitting on the bench in summer gets WAY MORE HOTTER than a polished barrel in the same sun............Therefore the polished barrel is going to lose it's heat faster as the black barrel heats up by just sitting there.

A few years ago I did a bunch of very crude experiments about barrel heat while on a PD shoot in South Dakota. I have a digital thermometer with a probe that is on a wire and fits down a .224 bore. We had a bunch of different rifles with different diameter barrels and a few flutted........Findings...(All reading were taken midway down the bore, internally. Comparisons were same cartridge, 6BR, 223 and 22-250)....Pencil barrels heat up the fastest, but cooled down the fastest. No difference between a fluted barrel and non fluted of the same overall diameter. Black barrels get hotter than polished barrels while shooting (see above) even if under an umbrella. No difference between polished barrels and bead blasted barrels........
 
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