Can you over polish the bore of a barrel.
- Thread starter borderghost
- Start date
So what causes the marks to go across or perpendicular to the grooves? you'd think they would be horizontal, those cross marks seem like a sure fire way to get more fouling.Can you over polish the bore of a barrel?
YES, if you remove all the button rifling marks the bore will be over polished!
I’ll try to keep this short.
Guy shooting BR match at St.L asks me to scope his barrel. Won’t shoot. Most copper I’ve ever seen. Everyone in loading room takes a peak and adds to his humiliation. Dave Coots even tries to buy mineral rights on the barrel.
One year later at East West Shootout same guy wants me to scope his barrel. Says barrel starts groups good but spitting before he finishes. Getting a lot of blue. Insert scope and almost get retinal damage. Bore looks like a mirror.
He improved his bore cleaning process with a heavy, regular dose of iosso.
Guy shooting BR match at St.L asks me to scope his barrel. Won’t shoot. Most copper I’ve ever seen. Everyone in loading room takes a peak and adds to his humiliation. Dave Coots even tries to buy mineral rights on the barrel.
One year later at East West Shootout same guy wants me to scope his barrel. Says barrel starts groups good but spitting before he finishes. Getting a lot of blue. Insert scope and almost get retinal damage. Bore looks like a mirror.
He improved his bore cleaning process with a heavy, regular dose of iosso.
^ But what about hammer forging such as a Sako TRG barrel that is renown to be extremely accurate and is as mirror smooth inside as the outside of the finest barrels?
That top picture’s barrel ^ is like a file. It’s hard to see how chatter like that could be desirable, for one thing because it’s distribution is more random than repeatable, such that every barrel is different.
That top picture’s barrel ^ is like a file. It’s hard to see how chatter like that could be desirable, for one thing because it’s distribution is more random than repeatable, such that every barrel is different.
Here’s a question I’m curious about.
When hard carbon starts to build up in layers with copper in-between what affect is it having on the steel underneath as successive rounds are pushed through it? I would think there would be more heat and pressure on the steel that might hasten throat erosion.
In other words, does not cleaning out the hard carbon out of a barrel shorten the life of a barrel?
When hard carbon starts to build up in layers with copper in-between what affect is it having on the steel underneath as successive rounds are pushed through it? I would think there would be more heat and pressure on the steel that might hasten throat erosion.
In other words, does not cleaning out the hard carbon out of a barrel shorten the life of a barrel?
BoydAllen
Gold $$ Contributor
Those are reamer marks. High grade buttoned barrels are reamed smoother than that, and then lapped to remove the marks before rifling, and then lapped again after rifling.Can you over polish the bore of a barrel?
YES, if you remove all the button rifling marks the bore will be over polished!
Boyd, if they are reamer marks why didn't the button rifling smooth them out?
In other forums they call this chatter marks from the button rifling.
BoydAllen
Gold $$ Contributor
Then in those forums they are wrong. In your picture you can see that the tops of the lands have deeper marks because button did not contact that area, but you can see that in the grooves they have been mashed down by that part of the button. I suggest that you send your pictures to a quality button barrel maker and ask what they are. Who made the barrel that you photographed? What are the details of their process?
Boyd, if they are reamer marks why didn't the button rifling smooth them out?
In other forums they call this chatter marks from the button rifling.
Mr. Allen hit the nail on the head...the only thing I would add is to your question: "why didn't the button smooth them out??" sometimes the button does. The finish reamed bore is smaller in diameter than the button. So it's kind of like a snake swallowing an egg. The rifling is literally swaged into the bore. The reamer marks you are showing are among the worst I have ever seen. Most of the time the few I see in Douglas or Shilen barrels have been "ironed" completely smooth by the button. You can still see the "shadow" or ghost of the reamer mark, but it is smooth nevertheless.
As far as "polishing them out" automatically meaning you over polished a bore or otherwise went too far....not necessarily, most of the high end button riflers will lead lap the bore and those marks will not be seen. Does it automatically make it shoot better to do that??? Not necessarily.
As to the original question, can you over polish a bore?? Absolutely. I have found that a 220 grit lead lapped bore is about right. What I cannot answer is why some barrels will still copper foul when everything is the way it should be. I wish I could answer that one!!!
dstoenner
Silver $$ Contributor
This has become one interesting topic for sure. Let me cut to the bottom line, I don't know if it makes any difference. I am relatively new to shooting as I got back into it in 2001 when I inherited my step father 1911 that he carried on 25 missions as the pilot of a B17.
At first it was just playing but then I got into competition shooting, NRA HP and military matches. That is when the round count started to climb and I started seeing some observations about barrels. For the most part all barrels seem to follow a pattern.
First disclaimer, I don't think I have ever had a cut rifled barrel till just 2 months ago. But I have had both cold hammer forged and button rifled for sure.
So here is what I have observed:
1) I have never seen a new barrel that settled into good groups before 100 rounds and some took 200 rounds. The first few rounds of a new barrel may have a small group but then they start diverging till about the 100 mark. The groups just get rounder, fliers go away and life is good. To me this says that the barrel is polishing itself to its best condition and reaches equilibrium. Our job is then not to disturb that equilibrium.
2) I have now had the position of having shot out 4 barrels. 2-223 match barrels, 1 6BR, 1 260 Remington F-Class. All sort of exhibited the same signs of getting old. The groups weren't as tight and they changed POI as more rounds were shot. If I JB Bore pasted the throat only really good the barrel would preform a little better for more rounds but then fall back into the same pattern. OK no surprise but I don't see that the problem is accumulation outside of the throat area.
3) When a barrel hits about 1000 rounds down it, I see that it cleans differently. It actually gets easier to clean till we start getting close to end of life. My regimen is to clean my barrel thoroughly after each range trip. I keep a log book and on the next trip to the range after I have had 200 rounds since the last time, the first 2 rounds downrange are Tubb TMS. I clean with Montana extreme bore solvent and Kroil/JB Bore Bright (that is mostly in the throat area with a few full length passes). My wife thinks I am OCD - I am. But I got 4000 rounds out of each of my 223 barrels, 3800 rounds out of my 6BR and 2800 rounds out of my 260 Remington. That doesn't seem to be any different than other figures I see here.
Several things I do in my routine maintenance are oriented at polishing. I guess I stumbled on this set by accident but it is working for me. But I personally think the answer is, as some have alluded to, we have to polish to some extent or we will not get the performance and useful life out of our barrels we want.
As a side note, I bought a 24 inch Krieger 1:7.7 Wylde for my 223. I just had to try one truly premium barrel in my life. I hope that it proves the forgoing 3 observations null and void. But I am not stacking my life on it.
David
At first it was just playing but then I got into competition shooting, NRA HP and military matches. That is when the round count started to climb and I started seeing some observations about barrels. For the most part all barrels seem to follow a pattern.
First disclaimer, I don't think I have ever had a cut rifled barrel till just 2 months ago. But I have had both cold hammer forged and button rifled for sure.
So here is what I have observed:
1) I have never seen a new barrel that settled into good groups before 100 rounds and some took 200 rounds. The first few rounds of a new barrel may have a small group but then they start diverging till about the 100 mark. The groups just get rounder, fliers go away and life is good. To me this says that the barrel is polishing itself to its best condition and reaches equilibrium. Our job is then not to disturb that equilibrium.
2) I have now had the position of having shot out 4 barrels. 2-223 match barrels, 1 6BR, 1 260 Remington F-Class. All sort of exhibited the same signs of getting old. The groups weren't as tight and they changed POI as more rounds were shot. If I JB Bore pasted the throat only really good the barrel would preform a little better for more rounds but then fall back into the same pattern. OK no surprise but I don't see that the problem is accumulation outside of the throat area.
3) When a barrel hits about 1000 rounds down it, I see that it cleans differently. It actually gets easier to clean till we start getting close to end of life. My regimen is to clean my barrel thoroughly after each range trip. I keep a log book and on the next trip to the range after I have had 200 rounds since the last time, the first 2 rounds downrange are Tubb TMS. I clean with Montana extreme bore solvent and Kroil/JB Bore Bright (that is mostly in the throat area with a few full length passes). My wife thinks I am OCD - I am. But I got 4000 rounds out of each of my 223 barrels, 3800 rounds out of my 6BR and 2800 rounds out of my 260 Remington. That doesn't seem to be any different than other figures I see here.
Several things I do in my routine maintenance are oriented at polishing. I guess I stumbled on this set by accident but it is working for me. But I personally think the answer is, as some have alluded to, we have to polish to some extent or we will not get the performance and useful life out of our barrels we want.
As a side note, I bought a 24 inch Krieger 1:7.7 Wylde for my 223. I just had to try one truly premium barrel in my life. I hope that it proves the forgoing 3 observations null and void. But I am not stacking my life on it.
David
borderghost
Border Ghost
There has been some great discussion on this topic , I am kinda picking up , as a barrel gets older ( more shots down it ) it is kinda polishing itself to much , as a lot on here are saying that you need a little roughness to let the bullet glide smoother , so can you extend the life longer by polishing it with a coarse lapping compound , to give it back some of that roughness as when new. I know there are a lot of other things that are involved , like throat wear , fire cracking , rifling corners are not sharp anymore etc . also one more thing , do barrel makers make the button or the cut rifling with a radius on the bottom of the groove , instead of making a round bullet conform to a flat area , kinda like pushing a round ball down a square tube , just something to think about with no shooting.
If you want to make your boat faster you sand the bottom to make it rough...
I guess high speed, low drag doesn't apply in some situations
.Yikes! I have some unopened Bore Bright. Guess I will return it.
What about Bore Tech Chameleon Gel?
I would try to exchange it for this: https://www.brownells.com/gun-clean...mbedding-bore-cleaning-compound-prod1160.aspx
The experiment I did took use beyond what I would expect as normal & prudent. I cleaned the bore as normal then short stroked Flitz enough(like 30mins worth) to polish the bore. Trip to the range showed immediate & extreme copper fouling. I expected that. Then I learned that coatings would not cover for this, then I learned that re-lapping to the point of reducing that unnatural fouling would destroy bore performance.
Basically, I killed the barrel for the learning, and it was worth it.
My friend did similar using JB Bore Bright, but he was shocked and sad about the results..
What got him there was long term use of moly, which has an affinity for itself and condenses, smears, and piles up about mid way down the bore. If this is not constantly managed it will lead to constriction & killing of accuracy. By that time, efforts to remove it with abrasives, will permanently kill the bore (just as we both did).
I have always used the blue label JB (normally), to manage carbon, and have never increased or caused copper fouling with it. There is no 'polishing' going on there.
IMO, POLISH as a bore cleaning term, is horrible marketing. Who knows how many people are really polishing their bores, to remove copper fouling, only to cause more of it (eventually).....
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