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Tuning Barrel Polishing?

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Have to agree with a couple of the other guys on here about not going against the rifling when polishing. Although most of my experience is in powder burners, I’ve been shooting for 55 years. And done some Gunsmithing on some of them. But it’s just common sense to polish following The rifling and not against it. That’s just crazy. You would be rounding off the edge of the rifling by doing that. 
 
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.I’ve seen that already. I don’t care how good he is supposed to be that don’t mean I have to agree to it. You would never get the rifling evenly polished that way.How would you get into the corners of the rifling that way? Then the top of the rifling would be too much danger of rounding the edges off. That looks like somebody that’s just in too much of a hurry to do it the right way. You Should Polish it the same way the rifling was cut. You would be taking more metal off the lands than you would the grooves.The only way I would believe it is if I seen somebody take a barrel that shot horribly and seeing him do it that way and make it shoot better. I’ve read many many articles about Bore Lapping and polishing. And There was a couple people that actually did it that way. I’m gonna go with the way I think is the correct way and what the other 95% of people say is the right way.
 
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.I’ve seen that already. I don’t care how good he is supposed to be that don’t mean I have to agree to it. You would never get the rifling evenly polished that way.How would you get into the corners of the rifling that way? Then the top of the rifling would be too much danger of rounding the edges off. That looks like somebody that’s just in too much of a hurry to do it the right way. You Should Polish it the same way the rifling was cut. You would be taking more metal off the lands than you would the grooves.The only way I would believe it is if I seen somebody take a barrel that shot horribly and seeing him do it that way and make it shoot better. I’ve read many many articles about Bore Lapping and polishing. And There was a couple people that actually did it that way. I’m gonna go with the way I think is the correct way and what the other 95% of people say is the right way.
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You are absolutely right, each one has to do it as the best result, some use a drill, others a lathe and another a chainsaw file
 
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I took 2-30 feet long poly/cotton cords that fit tite in bore WET with Kroil oil. I next strung them up across the shop one impacted with JB cleaner and the other one in JB Bore bright. Had friend pull the cord tite on one end as other end tied to eye screw in vise. One full pass down and back on JB cord= 60ft of cleaning one step one. cleaned barrel with brake clean and then one pass down and back on cord #2 with bore bright= 60ft of step 2. cleaned barrel with brake clean and got a mirror finish . Remember to coat the whole 30ft of ropes with kroil and JB/ JB bright. the rope will twist with the machining of barrel bore. One pass down and back only uses the compound twice and does not even change color as new fresh compound is feed in and not stroked over and over with a cleaning rod, Uses a ton of JB for one barrel but the result was flat out way better in surface finish.
 
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I do pretty much the same as Jason. With two additional steps. I first fire lap my slug barrels with the finest Wheeler fire lapping compound. Followed with diatomaceous earth mixed with a very light oil of my own mix. (JB bore paste is Diatomaceous Earth as well). 

The first step listee is difference number one.



The Diatomaceous earth is followed by Flitz Metal polish and then the final addition.



I have a product here in the shop called Pure Green Chrome Compound. It is used by custom Knife makers for the final, NO Haze brilliant shine on a fine blade. Expensive, and NASTY to use. I have seen some slug barrels go from a 20 to 25 shot arm befoer accarch falls off to well over 200 and 300 shots and just starting to not have the guilt edge in accuracy. Very little is needed to clean such a barrel. Slug shooting is completely different than shooting pellets. The friction is completely different and steps to help are well rewarded.



KnifeMaker
 
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In defence of E. Rowe, and with apologies to Motorhead who is quite the professional Air Smith, Don't discount rounding the edges of the rifling out of hand without research. 

I bring to the attention here of the older extreme if not possible legendary past BSA barrels which have convex lands rather than the normal square cut rifling, as does the newer TJ's hammer forged barrels. The very well know firm of Styer also uses this type of rifling in their sniper rifles and the new FX superior interior is a refined version of the same concept as is the polly bore.

Once the bore has been honed, a very light turning of a felt or nylon brush with a decent patch on it and spun lightly will break the sharp edge. It is not sharp by necessity but rather a sharp corner left form the rifling process. It is NOT Magic, and can be improved. 

Remember as well, that the 3-M product he is using is not a typical paper, but rather a soft, non woven abrasive sheet developed in Germany. We custom Knife Makers were the test moles in the beginning for this unique product. It is an amazing product by a company that test their products to the point of an obsession. The pink is not 3000 grit as stated but rather 4000 grit and the white is 8000 containing a very soft abrasive. I've used tt for years now. It can increase along with a good bore polish a bore that almost doesn't know how to foul. Iven with high power lead slugs. My current Brownells Gunsmithing barrel will pass 1000 shots without so much as a pull thru even at 130 to 1090 fps with my hand cast slugs consisting of 99% lead, 1% Tin. Those in the know will tell you that this is near impossible. It is that good!

Knife



DSC02656.1601393236.JPG
DSC02627.1601393327.JPG

 
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For what it’s worth, I advise against a spinning motion not because it rounds over the lands but because it promotes the abrasive skipping over the inside corners of the rifling, leaving this crucial area untreated and rough. That is precisely the spot where lead wants to abrade and stick in the first place. Using an in-and-out approach that follows the spiral of the rifling allows the polishing felt to conform to the profile better and scrub these sharp inside corners so lead will not be as apt to abrade and stick there.

To be clear, I’m speaking of conventional rifling (left). In the case of polygonal rifling (right), I have no reservation about using a spinning motion. 

https://en.wikipedia.org/wiki/File:polygonal_vs_normal_rifling.svg

Furthermore when you consider the myriad of rifling geometries out there, including the polygonal example above, it becomes clear there is no reason to suppose there is anything sacred about the sharp profile of conventional rifling. Rifling is just there to impart a spin. If the sharp corners are rounded over a bit, it will still perform that function just fine. Pretty much just as Mike (knifemaker) says above. So if you want to use a spinning motion to make the job go quicker, my advice would be to take care to apply a consistent amount of polishing along the barrel’s length. Or do as I described above and do more polishing near the breech and progressively less as you move out toward the muzzle, that way you don’t risk introducing a loose spot at the muzzle. Not to overstate it, the abrasives we are generally using (e.g. J-B) are so fine that it would require something bordering on gross negligence to ruin a barrel, so just a modicum of awareness is sufficient.
 
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No, lead and lead/tin/antimony alloys are far too soft to provide any appreciable smoothing.


Pretty sure the same can be said even of alloy (lead-free) pellets. If the material is soft enough for the skirt to obturate and form a proper seal in response to the pressure pulse, it is too soft to do anything.

You can always fire lap as an alternative though.
 
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Great points by everyone on this thread, and one of the best reads in a while. If there is one thing that I am certain of, it is that nothing is certain. I tend to come from the school of going with the bore, and still am with really quality barrels. However. I had a barrel that looked so bad, terrible machining marks down the bore and a super tight, long (2") choke, that I had determined to just throw out. It was a new .25 Crosman barrel, if that even matters to my point. Anyways, I decided to do everything wrong to this 'thing.' I used a drill on a rod and ran a boremop with JB on it, in forward and reverse, so that I would purposely hit both sides, and I did this for quite a while. Then I did it all again with bore brite. Then I finished, going with the bore, by hand with both polishes again. At this point I was just getting some exercise. From everything that I have read the barrel should have been destroyed by this point. I put it back on the gun just to see how much real world damage I did, and it shot (shoots) lights out. I never ordered the TJ barrel and never will at this point. I don't recommend doing this at all, usually, but hey, if you are going to pitch it anyways....
 
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Jason, (NT) I only do this in between fire lapping and the using the standard method with the two JB, or my own mix. I would never suggest the turing (spinning)method over or without a normal method being used both before and after. ;<) And NEVER on a premium barrel. X2!!!😉



Knife

Edit, I Do NOt think of L/W, Green Mountain, TJ's or CZ, or any of the common barrels we use on airguns as Premium. Premiumbarrels already come with full hand lapping from experts in the field. A few that come to mind right away, Lija, BenchMark, Shilen, and many, many more ands cost an arm and a leg for the barrel only, much less the machining to fit them to our guns. They are truly Premium barrels and cost like it!



Knife



. 
 
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Great points by everyone on this thread, and one of the best reads in a while. If there is one thing that I am certain of, it is that nothing is certain. I tend to come from the school of going with the bore, and still am with really quality barrels. However. I had a barrel that looked so bad, terrible machining marks down the bore and a super tight, long (2") choke, that I had determined to just throw out. It was a new .25 Crosman barrel, if that even matters to my point. Anyways, I decided to do everything wrong to this 'thing.' I used a drill on a rod and ran a boremop with JB on it, in forward and reverse, so that I would purposely hit both sides, and I did this for quite a while. Then I did it all again with bore brite. Then I finished, going with the bore, by hand with both polishes again. At this point I was just getting some exercise. From everything that I have read the barrel should have been destroyed by this point. I put it back on the gun just to see how much real world damage I did, and it shot (shoots) lights out. I never ordered the TJ barrel and never will at this point. I don't recommend doing this at all, usually, but hey, if you are going to pitch it anyways....



Yes Sir! Nothing lost in a last ditch effort, and your efforts shows exactly what I ham trying to show. I learned this method on barrels that were hopeless and all but one came out stellar! Impossible, but it worked!



One method I will strongly advise against is people using a bronze brush, (often called a brass brush) on a rod and then JB or other type polish put on it.
the grit simply runs around the bristles and does NOTHI
NG the brush would do on its own. And Never-Never use a bronze brush on a polished bore. Even larry Potterfield (Owner of Midway USA advises strongly against it. It will mar the extensive efforts put into a finely polished barrel



For those that do not know my history or name, I am considered one of the finest hard metal polishers and fit and finishers in the field. Not just in the U.S., But world wide. I did it for a living for over 45 years and have won many awards for my fit and finish and helping other professionals and manufacturers attain their goals in the field.



Then I tell you that something works, it works and has been tested over and over again. Most times to excess and exhaustively.



Knife

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I hand polish with JB bore paste and cotton squares on a cleaning rod and brass jag. Put a block of wood against the crown and do 200 strokes in and out from the breech changing the cotton squares with new ones and more polish every 50 strokes. I thoroughly clean the barrel before and after.
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To add to this, after JB bore paste I do the same with JB bore polish.
 
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Willie, Thanks. I now have a better understanding of the need (depending on which protocol I follow) in the following:



Need for cleaning rod that spins

Importance of blocking off the muzzle end as to not "round out" the crown

Not sure about the breech end. On the FX barrel there is the brass colored part that has the transfer port and o-ring. Shoud I remove this as to not damage those parts?

Thanks,
 
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Willie, Thanks. I now have a better understanding of the need (depending on which protocol I follow) in the following:



Need for cleaning rod that spins

Importance of blocking off the muzzle end as to not "round out" the crown

Not sure about the breech end. On the FX barrel there is the brass colored part that has the transfer port and o-ring. Shoud I remove this as to not damage those parts?

Thanks,
Click to expand...

I'd remove the liner completely. To do that, you'll need to heat up the parts with a torch through. Be sure to remove all the orings first.

You have to remove the liner anyway if you are going to install the CF tube.
 
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knifemaker said:
I do pretty much the same as Jason. With two additional steps. I first fire lap my slug barrels with the finest Wheeler fire lapping compound. Followed with diatomaceous earth mixed with a very light oil of my own mix. (JB bore paste is Diatomaceous Earth as well).

The first step listee is difference number one.



The Diatomaceous earth is followed by Flitz Metal polish and then the final addition.



I have a product here in the shop called Pure Green Chrome Compound. It is used by custom Knife makers for the final, NO Haze brilliant shine on a fine blade. Expensive, and NASTY to use. I have seen some slug barrels go from a 20 to 25 shot arm befoer accarch falls off to well over 200 and 300 shots and just starting to not have the guilt edge in accuracy. Very little is needed to clean such a barrel. Slug shooting is completely different than shooting pellets. The friction is completely different and steps to help are well rewarded.



KnifeMaker
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I know this is a very old thread but your comment on your diatomaceous earth struck a cord with me. I happen to have a 25lb bag that I just bought of it and wondered what your recipe for it is? Can I use it instead of JB paste?
 
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You can make a slurry with most any oil or automatic transmission fluid...add more or less of the oil and DE until you end up with a peanut butter-like consistency.

Just be aware DE can have widely variable particle sizes so my recommendation would be to take a scrap of mild steel with a polished or near-polished finish and briskly rub some of the slurry on it to see how it affects the surface. It should produce some dulling of a polished surface but not leave any coarse scratches.
 
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