bore barrel polishing

[tronickero]

Hello

I want polish the bore of my Qb79 barrel (so that the accuracy improves or I hope so) but here in Chile is not posible buy the JB bore paste, I see in aliexpress a polishing pastes

Will they serve for this purpose? or will it only damage my barrel? what number in the image recomend?



Tron

[nervoustrigger]

That listing looks like some diamond paste that someone asked about recently.  My concern is that it may embed into the bore or the cleaning rod.  Whereas diamond is much harder than steel, polishing agents like J-B or something generic like rottenstone is softer so it won't embed, but achieves its purpose by being friable, meaning the cutting surface is constantly being renewed as it breaks down through abrasion. So I suggest looking for rottenstone instead.

[Bullfrog]

That listing looks like some diamond paste that someone asked about recently.  My concern is that it may embed into the bore or the cleaning rod.  Whereas diamond is much harder than steel, polishing agents like J-B or something generic like rottenstone is softer so it won't embed, but achieves its purpose by being friable, meaning the cutting surface is constantly being renewed as it breaks down through abrasion. So I suggest looking for rottenstone instead.

I agree. I wouldn’t want to put any sort of diamond in my barrel. I use synth diamond to sharpen knives made of exceptionally hard steel, steel that is so hard that traditional whetstones can’t sharpen it. I have no doubt that diamond in a steel rifle barrel would ruin the rifling.

The key to aggressive barrel cleaning is to never put anything in the barrel that is as hard or harder than the barrel steel. As long as your rod, brushes, and polishing compounds are softer than your steel you’ll be ok. But put something hyper hard like diamond and its bound to cause damage.

[Model25]

I will second the use of rottenstone. I have used a slurry of rottenstone and light oil-ATF to polish rough actions and barrels for decades. I don’t know if it comes in different grades. The stuff I use is 40+years old and is as fine as corn starch. It is sold as a fine finishing compound for wood work finishes. I used it to fire lap the bore of a particularly rough .44 and the accuracy improvement and the reduction of leading was remarkable. Even the clueless kids notice.
Have fun with it, Mike

[WyoMan]

I would have to say that I never had to "polish" an airgun bore with anything other than lead. Several hundred down the pipe, along with some periodic cleaning, will generally remove the microscopic irregularities from the machining processes. I clean with very tight patches loaded with a benign oil (WD-40 or Hoppe's Elite).

I see lots of folks that have to polish the bore. I don't understand why. I have over 30 barrels in use - they are LWs cut from blanks, HWs and TJs. I don't wash or lube pellets and shoot straight from the tin. I use JSB and H&N pretty much exclusively... and after the break-in period, they shoot a long time before they foul... maybe just shoot and clean for a while?...

Wyo

[Motorhead]

600 or 800 will get rid of the surface fretting on bore surface.

[tronickero]

Thanks for all replies, here in Chile there are not rottenstone, but I can get dental pumice stone powder ...can work?

Tron

[K.O.]

3 parts toothpaste one part baking soda...

[Mod90]

3 parts toothpaste one part baking soda...

I thought I was the only loon to use this formula 
It's cheap & it works. I add just a little mineral oil to it.

[rkr]

That listing looks like some diamond paste that someone asked about recently.  My concern is that it may embed into the bore or the cleaning rod.  Whereas diamond is much harder than steel, polishing agents like J-B or something generic like rottenstone is softer so it won't embed, but achieves its purpose by being friable, meaning the cutting surface is constantly being renewed as it breaks down through abrasion. So I suggest looking for rottenstone instead.

I agree. I wouldn’t want to put any sort of diamond in my barrel. I use synth diamond to sharpen knives made of exceptionally hard steel, steel that is so hard that traditional whetstones can’t sharpen it. I have no doubt that diamond in a steel rifle barrel would ruin the rifling.

The key to aggressive barrel cleaning is to never put anything in the barrel that is as hard or harder than the barrel steel. As long as your rod, brushes, and polishing compounds are softer than your steel you’ll be ok. But put something hyper hard like diamond and its bound to cause damage.

Why would it ruin the rifling? If it embeds itself in rifling (as was suggested) it would be extremely fine and cause minor abrasive action on bullets. The rifling would still be smoother and cause less damage to bullets than a non-lapped barrel. I find it a bit hard to believe that tiny pieces of diamond would embed themselves in steel, it sounds more like one of those knives you could buy from shopping channel. It's much more likely that the diamond dust would embed itself in the lead lapping die and bullets than steel.

[cootertwo]

I have been confused about this bore polishing thing too. I could very well be wrong, but have always had the opinion that the sharper the rifling, the better the bore, and it would seem all this running abrasive compound through the barrel, would dull the edges of the rifling.

[rkr]

I have been confused about this bore polishing thing too. I could very well be wrong, but have always had the opinion that the sharper the rifling, the better the bore, and it would seem all this running abrasive compound through the barrel, would dull the edges of the rifling.

If the rifling is rough or very sharp then lead will build up on lands causing this:

leading_zpseee287ee by abbababbaccc, on Flickr

[Job]

Can this procedure be useful for air gun bore polishing?
http://www.accuracysystemsinc.com/Barrel_Break-In.php
https://www.aliexpress.com/wholesale?catId=0&initiative_id=SB_20171120075344&SearchText=bore+snake

[nervoustrigger]

B.Bob, the purpose of this polishing is to remove the surface fretting of the steel that Scott described. The most common method of applying rifling is a process called button rifling which involves forcibly drawing a very hard mandrel through the bore.  Depending on the grain characteristics of the steel and the quality/condition of the button, fine imperfections on the surface of the bore are created.  In other words, the surface quality of the bore is affected.
 
So the goal is to remove this microscopic surface roughness without substantially affecting the profile of the rifling.  With the fretting smoothed down, the bore will not be as apt to abrade lead from the pellet, leaving it stuck to the walls...but the pellet will still become neatly imprinted with the overall rifling profile.
 
I'd like to add that we frequently see example photos of a pellet or bullet with distinct or sharply defined engraving marks as a classic example of good rifling.  But I think you can draw a distinction that "sharp rifling" and "sharply defined engraving" are two different things.  Bearing in mind that the purpose of rifling is to impart a spin, there isn't necessarily any requirement that rifling have the prototypical orthogonal sharp edges.  Google an image of polygonal rifling and notice the lands have a sort of smooth, rounded profile.  FX's Smooth Twist is another example.
 
 
 

[Horatio]

B.Bob, the purpose of this polishing is to remove the surface fretting of the steel that Scott described. The most common method of applying rifling is a process called button rifling which involves forcibly drawing a very hard mandrel through the bore.  Depending on the grain characteristics of the steel and the quality/condition of the button, fine imperfections on the surface of the bore are created.  In other words, the surface quality of the bore is affected.
 
So the goal is to remove this microscopic surface roughness without substantially affecting the profile of the rifling.  With the fretting smoothed down, the bore will not be as apt to abrade lead from the pellet, leaving it stuck to the walls...but the pellet will still become neatly imprinted with the overall rifling profile.
 
I'd like to add that we frequently see example photos of a pellet or bullet with distinct or sharply defined engraving marks as a classic example of good rifling.  But I think you can draw a distinction that "sharp rifling" and "sharply defined engraving" are two different things.  Bearing in mind that the purpose of rifling is to impart a spin, there isn't necessarily any requirement that rifling have the prototypical orthogonal sharp edges.  Google an image of polygonal rifling and notice the lands have a sort of smooth, rounded profile.  FX's Smooth Twist is another example.

^+1

Benjamin brass barrels and Glock barrels can be pretty accurate without sharp edges.

[rsterne]

Grit will always become embedded in the softer material, and will then abrade away the harder material.... That is how lapping a barrel works, be it with a felt fob, a lead lap, or fire-lapping with a lead bullet coated in abrasive.... There is no mechanism to imbed grit into a smooth, hard surface, although it can remain behind in hollows, but can then be easily removed with a solvent for the carrier....

In the absence of grit or dirt, the softer material will wear away first, and if the harder material is not smooth (such as a barrel with fretting) it will remove more of the soft material (from the bullet) which will tend to imbed in the irregularities (causing leading).... Our velocities and gas temperatures are not hot enough to melt the lead (like in a PB), our leading comes from microscopic irregularities in the bore (or the constriction of a choke) abrading away the pellet/bullet as it passes by.... The smoother the bore, the less lead scraped away, and the longer between cleanings.... Even relatively rough bores get better with age, as the microscopic hollows fill with lead, which is why barrels seem to "break in" and become more accurate with time....

Bob

[KnifeMaker]

For a very long time now, BSA barrels have had a stellar rep. for accuracy.
If you get the chance to really look at the bore of a BSA, you will see softly rounded edges to the lands. This will greatly lessen leading, and result in longer accuracy form a given barrel.

My .257 barrel, is different than any other .257 from TJ's I have seen.  The grooves are wide, and the lands narrow. However, accuracy would diminish quickly. 25-30 shots and it would start shotgunning.

Remembering the older BSA barrels, I decided to try something. (I had two TJ barrels, so noting lost if it didn't work).

First, I put crocus cloth in a slit end dowel rod, and spun it both clockwise and anticlockwise with a DeWalt cordless drill motor. This to break the very sharp corners of the rifling. Followed by hand lapping with same setup. 

The difference was remarkable. However, I was still getting leading in the groves. So I followed this with a Wheeler firelaping kit. 40 shots with the coarse grit embedded in presized bullets, then 500 and 600 grit if I remember right.

Further, Followed this with a bore mob coated with flitz metal polish rubbed into the mop. Gave it a LOT of strokes, stopping just shy of the muzzle until the very last 20 strokes, removing the mop each time, rather than drawing it back thru the muzzle.

Accuracy went from well over an inch at 80 yards, to 3/8 to 1/2 inch at the same distance.

Cleaning for accuracy went from 25-30 shots to well over 200 instantly.

What was a little scary, turned out to give me  a great barrel in the end.

I think this fits the old saying, nothing ventured, nothing gained. LOL 

Knife

[tronickero]

thanks guys! in conclution i can use the diamond polish compound but need remove it with solvent and procure no leave any residues after the process.

That is what I understood? or im wrong? LOL 

Tron.

[plinker81366]

i would try some zeolite first mixed with some oil..

[nervoustrigger]

in conclution i can use the diamond polish compound but need remove it with solvent and procure no leave any residues after the process.

Tron, the issue isn't so much about whether the diamond compound will work to polish the bore, it's that the abrasive will embed into the cleaning rod.  I do not see how a solvent can remove it when it is mechanically bonded to the rod.  But frankly I don't suppose it's all that bad if you will never use the rod from the muzzle end of a barrel.  Polishing should be done from the breech end anyway but on occasion you may find a need to use the rod from the muzzle end, such as to dislodge a stuck pellet.