Final Bore Polish- What would it be?

[Gtek]

Not trying to chase bore dimension problems, just polish out to extreme just cause!. By Hand with rouge or compound? Boolits with compound? Paper patch-straight up, Paper patch with compound. Stainless vs. Moly?:popcorn:-Gtek

[excess650]

If the lines run lengthwise WITH the bore, don't worry about them. If they're concentric I would just run a lap through so the bore didn't have loose or tight spots.

I had a barrel that had been removed from another rifle that had been shot extensively. It was mirror smooth inside, but the throat was worn. The previous owner had cleaned it with Corbin bore cleaner every time he shot it(BPCRS). The Corbin felt like chrome polish, and you could feel the grit in the cleaner. I had it fit to one of my actions, but shortened several inches to remove the majority of the wear, and it ended with about .0015" taper from breech to muzzle. I thought it would be great....it would group really well for several shots and then open up. I think that there were no machine marks in the bore(to hold lube) and it was leading badly. That was enough to convince me that mirror bores weren't what it took to shoot without leading.

[btroj]

Yep- I don't think any of the custom barrel makers polish beyond about 320 grit o so. I am sure someone else can set exactly what they use for a final lapping. If a mirror finish was a good thing wouldn't the users of the custom barrels demand it? My understanding is that going to a higher polish finish increases friction which leads to worse fouling, not less. Granted, this is with jacketed but I wouldn't be at all surprised to find that cast behaved the same way.
When I fire lap is use 320 grit and call it good. No leading. All you need to do is remove choke points in the barrel and smooth out rough spots. You are NOT trying to polish the barrel, just remove the major bad spots.
I think this is a bad idea. You may do what you chose wi your barrel but mine will stay with the slightly rougher but very, very acceptable finish.

[Char-Gar]

I am not a believer in jacking with a rifle barrel, "just because". If there is no problem, there is always the chance of creating one. "If it ain't broke, don't fix it!"

[geargnasher]

I tend to agree with Chargar, but if you insist, shoot about 100 paper jacketed boolits through it using printer or notebook paper. Use starting loads for equivalent weight copper-jacketed with the slowest powder practical. There are enough mildly abrasive fillers in the paper to do the trick. Once you try the paper jackets, you might not go back to plain grease-groove boolits again.

Gear

[williamwaco]

Yep- I don't think any of the custom barrel makers polish beyond about 320 grit o so. I am sure someone else can set exactly what they use for a final lapping. If a mirror finish was a good thing wouldn't the users of the custom barrels demand it? My understanding is that going to a higher polish finish increases friction which leads to worse fouling, not less. Granted, this is with jacketed but I wouldn't be at all surprised to find that cast behaved the same way.
When I fire lap is use 320 grit and call it good. No leading. All you need to do is remove choke points in the barrel and smooth out rough spots. You are NOT trying to polish the barrel, just remove the major bad spots.
I think this is a bad idea. You may do what you chose wi your barrel but mine will stay with the slightly rougher but very, very acceptable finish.


I am not a mechanic or machinist. Don't know anything about making or polishing steel parts or tools or barrels.

I do know this. 320 grit wet or dry looks and feels pretty rough but if you polish something with it, it makes it really smooth.

Now the question. What is the grit size of JB's bore polish? I think it is much finer than 320 and after a few uses, it leaves a bright mirror finish which does not lead. It has been around at least 40 years. If they sold only 1000 jars per month, that is a half million jars. There is no doubt it has been used on several million barrels.

I have never heard anything but rave reviews about how good it is. (And I agree it is great.)

So how fine is fine enough? How fine is too fine?

[Char-Gar]

There is not way in H$%% I would shove 320 grit down a barrel just for the fun of it. I have polished enough metal to know how abrasive it is.

I have polished a few sixgun barrels that proved to be chronic leaders due to mico-machine hickies. I fire 200 rounds of jacketed bullets, real fast, clean with a good bore solvent and JG paste and then polish with Flitz or Semi-Chrome metal polish. None of these are anywhere as near as abrasive as 320 or even 600 or even 900, or even 1200 grit.

[btroj]

JB is used to clean a bore, not polish it. It is designed to remove fouling, not metal from the bore itself.
Chargar is right- screwing with a barrel "just because" makes no sense. Do you want to chance ruining it?
I have used 320 grit for fire lapping- but only when the gun needed it. Only for a few guns and all were revolvers with thread choke. This was most definitely not "just because".

[nanuk]

I would assume a mirror smooth bore would be a poor choice for J-words, but for cast, I can't see how it can be too smooth

[Gtek]

Well gentlemen, Thanks for the thoughts. I have never tried to super polish one just cause. I have a ritual of pushing mid - grade barrels a hundred times with red top JB before I chamber / srcew them on. High end = (the expensive ones) just get a couple more or less for feel and on they go.
Blue lid on bench as needed at range. As I suspected- eight replies, eight differing thoughts. Ford, Chevy, Dodge. If we were all the same, do you think it would inspire the thought and passion we have? Thanks again -Gtek

[Char-Gar]

Not trying to chase bore dimension problems, just polish out to extreme just cause!. By Hand with rouge or compound? Boolits with compound? Paper patch-straight up, Paper patch with compound. Stainless vs. Moly?:popcorn:-Gtek


I am at a loss to understand why folks post something like the above and then later say they really didn't mean it.


"Well gentlemen, Thanks for the thoughts. I have never tried to super polish one just cause." Gtek

[KCSO]

Shoot cast bullets!

[waksupi]

On old black powder rifles, when they got shot slick, they had to be re-cut, to shoot well again. That may well be the case if you try to "improve" your firearms.

[shooter93]

Ed Harris has done extensive work on bore smoothness and bores can be too smooth. I can't remember the micron finish he said they had found the best but if you shoot him a line I'm sure he'd tell you.

[williamwaco]

Tried to find what Jim Brobst said about J-B Bore Paste. Is it only a cleaner or is it a polish. Ot both?

I was very unhappy with his answer.

He said that he was very sorry but that due to circumstance beyond his control, J-B Bore Paste was no longer available.

You better grab a couple of jars while you can.

[zomby woof]

Tried to find what Jim Brobst said about J-B Bore Paste. Is it only a cleaner or is it a polish. Ot both?

I was very unhappy with his answer.

He said that he was very sorry but that due to circumstance beyond his control, J-B Bore Paste was no longer available.

You better grab a couple of jars while you can.

Brownells now carries both JB products. It's readily available.

http://www.brownells.com/.aspx/pid=1160/Product/J-B-reg-NON-EMBEDDING-BORE-CLEANING-COMPOUND

[Gtek]

Mr. Char-Gar, I am sorry if you felt I had wasted your valuable time. I did mean it which is why I posted question. I do admit to sometimes not expressing myself correctly, and for that I truly apologize. The question is in regard to achieve the perfect Boolit bore. I asked the question and should have been a little more descriptive in my quest. I am a rifle crank, I shoot .284" to .461" Boolits, I am an active Schuetzen match shooter. I have a Chrono. I am not an idiot! I have not had the extreme pleasure or time to do a set up and possbly waste a barrel testing to the point of performance decline. My mind tells me the smoother the better for a boolit without losing land edges, in which there were replies leaning both ways. I am sure that fit and lube become MORE critical at a certain point, more so than the point where a given set up works. Thank you all again for your replies- Gtek

[nanuk]

On old black powder rifles, when they got shot slick, they had to be re-cut, to shoot well again. That may well be the case if you try to "improve" your firearms.

when I first started thinking about cast in rifles, this site was one of the first I found, and I came here often and read a lot of archived data.

As well, I read several books I bought and online articles.

at the time, I believed the consensus was a Boolit rifle cannot be too smooth, because to get there, you would then also have "Dimensional Perfection"

in other words, to get a bore mirror smooth, you would have then also removed any and all high spots, and have created a perfect tube, or with a slight choke.

to that end, I bought a supply of differing grits of AlOx to try lapping on ONE rifle, and it would be my dedicated Cast Shooter. I laid in my supply to 4000grit ( I think, or finer ) and also some polishing compounds. ( I never did find any rottenstone for reasonable price at the time )

Then I read more, and decided to wait and do some more research.

Now, I read Waksupi's post and it brings back a memory of an article I read years ago, regarding pure copper jackets, and Cast and how the smoothness affected both.
I wish I could find that article again.

I have thought about BP and smoothness some time ago also, with ML rifles. I was thinking abrasion may be a concern, because all wood contains dust, but dismissed that as too fine to worry about, and the bore would show abrasion all through its length. Now that MAY be a cause of concern, but to date, I have never heard anyone mention it and there have been literally tonnes of BP fired in modern times, and if that really was an issue, it would have been discussed by now.

Yet, we still have guys talking about PPCB's polishing their bores to a mirror, and no loss of accuracy.

I will NEVER shoot enough to be able to test to any degree of statistical relevence to measure this issue, but would enough reading more on it if anyone has some links to articles by the ODG's or our Modern Era shooters, both BP and Smokeless.

[Char-Gar]

nanuk.. This cast bullet and rifle shooting stuff is chock full of different and often contradictory opinions on just about everything.

At the end of the day, a fellow will have to decide for himself what to do. If a fellow laps/polishes a barrel and it does better, he thinks everybody should do that. If a fellow turn a good barrel into a less than good barrel with the same stuff, then he thinks the whole idea stinks.

My experience has taught me I can get all the accuracy a rifle has to give without such measures, so I am not a fan of jacking with the bore. I have never want to risk a known accurate barrel just to guild the lily so to speak. But, to be honest, I am very traditional and old school in every area of life, including shooting.

Other may went to do such things and I affirm their right to do so, but when they ask for opinions and experiences on this board, I am not reluctant to give them mine. Different folks put their own out there and others just have to take their pick.

[btroj]

I will admit that shooting cast is a bit different from jacketed. If a mirror finish was better then wouldn't the custom barrel makers be using it? Would not the BR crowd demand it? The HP shooters too?
The very fact that custom barrel smiths don't use an extremely fine finish tells me it isn't "best". These guys sell barrels to people who demand the best.

People are certainly welcome to do as they wish with their barrels. Me, I leave mine alone unless they need some sort of work. Amazingly very few need anything.

[Char-Gar]

Mr. Char-Gar, I am sorry if you felt I had wasted your valuable time. I did mean it which is why I posted question. I do admit to sometimes not expressing myself correctly, and for that I truly apologize. The question is in regard to achieve the perfect Boolit bore. I asked the question and should have been a little more descriptive in my quest. I am a rifle crank, I shoot .284" to .461" Boolits, I am an active Schuetzen match shooter. I have a Chrono. I am not an idiot! I have not had the extreme pleasure or time to do a set up and possbly waste a barrel testing to the point of performance decline. My mind tells me the smoother the better for a boolit without losing land edges, in which there were replies leaning both ways. I am sure that fit and lube become MORE critical at a certain point, more so than the point where a given set up works. Thank you all again for your replies- Gtek

Gtek.. We don 't know what you mean. We only know what you say. If we react in a negative manner to what you say, then don't get miffed about it. Just give us enough information about yourself and the shooting issue for us to give an intelligent and informed opinion/answer.

There is a big difference between lapping a barrel to remove find mico-machine burrs and polishing an already smooth bore. Sometimes folks think that if lapping is good, then continuing the process to a glass smooth finish is better. That is not the case.

[felix]

Somewhere around 800 grit is about the smoothest the barrel should be. Must have room between the barrel and the projectile for a "bearing". Missing bearings allow for severe fouling to build in between the rubbing objects. Greased paper patching is prolly the best bearing material we can use with boolits. There is nothing wrong with using shotgun filler behind condoms to minimize blow-by which destroys the "load" over time. ... felix

[williamwaco]

Brownells now carries both JB products. It's readily available.

http://www.brownells.com/.aspx/pid=1160/Product/J-B-reg-NON-EMBEDDING-BORE-CLEANING-COMPOUND


Yea, That's why I said you better buy a couple. I bought a jar from Midway 6 months ago and they non longer ever list it in their web site.

[geargnasher]

My feeling is that the term "mirror bright" is a figure of speech. The barrels of my guns that have been polished with paper-jackets to a "mirror finish" after a couple hundred rounds will practically blind you if you look in one end while shining an LED bore light in the other. HOWEVER, the actual surface still shows the regular pattern of boring marks on the lands and cutting marks in the grooves. The only true, mirror polish I've found so far is on the leading edge of the lands in one rifle, where abrasion has removed all traces of tool marks.

There is a huge difference in sliding friction characteristics between a 98% contact situation and a 50% contact situation. I would think if a barrel ever got "too smooth" a few low-velocity rounds with boolits embedded with 400-grit valve lapping compound would take care of that situation in short order.

Gear

[nanuk]

I'm hearing you guys!