Polishing the bore

[CWC]

I've read several posts that mentioned using some type of abrasive to "polish" the bore. I recall that someone said they use steel wool, and another used a polishing compound on a patch. I'd like to hear some opinions about the value of doing this, as well as some detailed how-to's. The reason I ask is because I plan to cone my .54 GPR, and am thinking about doing the polishing thing as long as I'm screwing with the bore anyway. Thanks!

 

[Blizzard of '93]

get a jag the next size down from the bore. get a 3M handpad at ACE hardware (fine grade if bore is in good shape to begin with) and cut a 'patch' from it. force the 'patch' down the bore with the jag, it will be a tight fit some lube is called for WD-40 will work. clean well after you expend the elbow grease. may take 3-4 'patches'.

 

[BrownBear]

Some folks advocate fire lapping. I haven't tried it myself, but advocates often cite this writeup on the topic.

 

[redwing]

Fire Lapping is the only way to go. If you have a rough bore in modern or Black Powder guns. It works very well in modern handguns. It works much better than the old scrub cleaning, hard work polishing. :thumbsup:

 

[paulvallandigham]

There are two reasons to lap or polish a bore. One is to remove rust that was allowed to take hold because a gun was not stored or cleaned properly. Along the same lines, some barrels come from a manufacturer still with burrs on the edges of the lands, which cut patches. These will shoot out in about 200 shots, but many shooters are impatient. Use Steel wool, or the green scrubber pads, to clean up the guns. You can use toothpaste as a lapping compound as it has a mild, fine, abrasive that works well, and washes out easily.

The other reason to lap a barrel is to put " Choke " in the rifle barrel to aid accuracy. Target shooters do this kind of thing, usually from the breech end of the barrel, with the breechplug removed. They cast a laping section with lead, around a steel range rod, and lap the barrel by hand to make it baby skin smooth, and to make the muzzle of the barrel smaller by a few 10,000ths of an inch that back at the chamber. They usually leave the last 4 inches behind the muzzle alone. Then they divide the rest of the length of the barrel in quarters. They run a lap with a lapping or grinding compound on it back and forth in the REAR quarter section 50 time. The lapping compound is freshened whenever it seems the lapping is becoming too easy. The lap itself may be also recast periodically. Its all based on feel, and what the lap looks like after each stroke. Then the back HALF is lapped 50 times, with the same attention to feel. This gives the REAR quarter 100 strokes, and the second quarter 50, when that is done. Then the same process is done with the third and fourth quarters. When the barrel is done, the Rear quarter has been polished with 200 strokes, the next quarter, 150 strokes, the next, 100 strokes, and the forward most quarter, just 50 strokes.

Then the lap is run back and forth a few times to removes and " steps" that might be " felt " more than seen in the barrel. This produces a nicely polished, choked barrel, that continually squeezes the PRB tighter as it proceeds down and out of the muzzle of the barrel when fired.

The target shooters swear by this. They also have other things they do during a match to keep their barrels at their best, but this is a good start. With a good tight patch over a bronze brush, or a cleaning jag that has been reduced in diameter to carry a tight patch with lapping compound, there is no reason this same thing can't be done from the muzzle of the barrel of a gun.

 

[E Poffinbarger]

CWC:
As you have noticed, people all do things differently, I don't cone or choke my barrels.

However, I am strong believer in a highly polished bore. I use a long thick tight patch and Rubbing Compound, repeating the process using Polishing Compound then again with two grades Jewelers Rouge requiring about 250 strokes for each of the four compounds.

IMO, the resulting polished bore fouls less resulting in more consistent accuracy and then cleans easier.

Osage

 

[J.D.]

As Paul said, there are only two reasons to lap a bore. Simply polishing a bore, just for the sake of polishing will cause more harm than good.

A properly lapped bore is a thing to behold, but properly lapping a bore is MUCH more involved than simply scrubbing with an abrasive on a patch.

An improperly lapped/polished bore rounds the edges of the rifling, essentially creating wear that shortens barrel life...at the very least, without getting down into the grooves where rust is most likely to occur.

Lapping/polishing also needs to be done from the breech, and you will not remove the plug from that GPR without damaging the barrel, breech, and the threads.

IMHO, I suggest that you leave it alone. Cone the muzzle, but leave the bore alone.
J.D.

 

You got that right buddy :applause:

 

[410-er]

Whenever I get another muzzy,the 1st thing I do is jag,0000 steel wool,and oil.After a good bath to remove any oil its off to the range.Make a big difference in accuracy.

 

[longcruise]

Firelapping is the fastest and simplest method of conditioning a barrel.

I have firelapped more ml and modern barrels than come to mind without consulting my notes. That included three GPR barrels which benefited more than any of the others. All of the Spanish barrels I've played with were very sharp patch cutters right out of the box.

It's absolutely essential that you use the correct firelapping compounds. Using valve grinding compound or other makeshift compounds will usually cause damage. I use LBT or Wheeler compounds rolled into hollow base conical bullets and fired with 20 or 25 grain powder charges. Wipe the barrel thoroughly between shots. Fifteen or twenty shots will do the job.

 

[misfire99]

I tried an experiment with my sharps copy in 45-70. I used action magic on it from Brownells. What I was trying to do is cut down on fouling and the use of a blow tube. I had tried this on other smokeless rifles and it worked great. But the 45-70 with black powder is another story. It does stop the fouling from sticking to the bore. When I drop the block you can see the fouling just sitting on the bottom of the barrel. All you have to do is point the muzzle down and it falls out leaving a clean bore. This makes shot to shot fouling the same every time. But it reduced friction so much that the bullets don't obfuscate to fill the bore and engage the rifling. The only bullet I have gotten to shoot out of it was a LEE 405gr hollow base bullet. I believe the hollow base allows the bullet to expand to fill the bore. My next attempt will be with paper patched bullets. I have high hopes for them.

 

[paulvallandigham]

Why not simply use a .460 cal. fiber wad under that flat based bullet? It will seal gases behind the bullet, clean out and crud in the barrel as it goes out, and seal gases to give a better burn of the powder behind it. I recommend Walter's Fiber Wads, because they have down so well for me. You can make your own, of course, if you have a .45 cal. punch.

 

[Stumpkiller]

If the bore isn't rough I wouldn't mess with it. I've attacked rust with steel wool on a wire brush but, as noted previously, that rounds the edges . . . perhaps more than is desired.

I have an L.C. Rice barrel that is swaged with a carbide die. S m o o t h. If all makers would take that step we wouldn't need to be-burr machining marks.

I've used the 3M pad method on all of my T/C barrels to good effect. Mine all had "chatter marks" where the tools skip. Shooting 200 rounds is the best method of all. If you still have a rough spot THEN get more aggressive.

 

[roundball]

I had Ed Rayl in West VA put .012" x 1:72" square bottom grooves in a GM .62cal Flint smoothbore to make a rifle out of it...I asked him what I needed to do to it when I got it...ie: lap the bore, have a crown done, etc...he said it would be 100% ready to go to the range when I got it back...all crowned and polished...sure enough, it's a dream to load, as accurate as can be, and fouls very little...he did a terrific job...(one of the best $65 I've spent).

 

[redwing]

So true nothing like the first shot from a Rice barrel. The ball slides down the first time like you have been shooting the rifle all your life. :thumbsup:

 

[paulvallandigham]

The Rice brothers cut rifle their barrels. Then they run a button through the barrel to smooth the lands and grooves. If there is any roughness seen after these two procedures, they scrap the barrel. That is why the barrels are so smooth.

Other barrel makers do lapping, with poured lead laps, on a rod, with lapping compound, lapping the bore before the breechplug is fitted.

I agree that with many barrels, you can do as well shooting the gun a couple of hundred times, and you probably need to shoot it that much just to learn the gun. Fire Lapping is an outshoot of this kind of thinking, and it seems to work fairly well. The hard part is convincing shooters to get some fine lapping compound and put it on the Patch before loading the RB.

I Understand some of the men who shoot the Chunk Gun Matches use a brass fitted scraper to remove a find layer of the lands to give them a new " edge" for the next day's shoot. Personally, I believe that is going a bit far, but the guys doing it in their motel rooms over night swear they shoot better for doing it.

 

[doublesnider]

HI,
You have more experience then me on polishing barrels. I never have any problem with my underhammer as its barrel was button rifled and very smooth.
I have just bought a Pedersoli Kodiak double rifle almost mint condition.
I have not shot it yet but I find that rifling is cutting my cleaning patches at the edge.

Should I polish it or just shot it and wait until it polished it self?
I have some LBT lapping so I can try some fire lapping.

Thanks
Martin

 

[paulvallandigham]

Welcome to the forum, Martin. The answer to your question depends: Have you examined the muzzle to see what kind of crown has been put on the barrel? Often, cut patches occur simply because there is little or no crown to the muzzle. The patches cut before they hardly enter the rifling!

To check that, simple run the patch into the barrel a 1/4" and pull your jag back out. If the cuts are there, get some emery cloth, and the round end of a file handle, wrap the hanle with the emery paper and turn it around in the muzzle, to smooth down those edges. It doesn't take much polishing to get rid of the edges that are cutting your patches. I always do this with a clean, Dry barrel, because I am going to get grit down into the barrel, I want to be able to upend the barrel and tap its sides to get the big stuff out! The small stuff will come out with a dampened cleaning patch.

Next, make sure the Jag you are using is not to large in diameter for the bore. You need to meaure the land to land diameter as well as the jag with a Caliper to determine this. Your jag should be stepped, that is, the widest portion should be the first " ring ", and each ring after that should be slightly smaller in diameter. That allows the jag to pull crud out of the barrel, when the part of the patch back of the from ring blouses, or bunches up, and fills the grooves. The Largest ring diameter needs to be at least one patch thickness smaller than your land diameter. If that is still too tight, then put the jag tip in the chuck of a drill or drill press, and use a file to reduce the diameter further. Then reduce the diameter of the other rings back in similar proportions.

Now, if your patch is not being cut at the muzzle ( This happened with my first ML rifle, BTW, which is why I spent some time discussing it) and is being cut by burrs or very sharp edges on the lands, then some kind of polishing is in order.

First, fire the gun, and check each patch that is fired. Sometimes rifling will cut cleaning patches, but not shooting patches that are properly lubed.

If the burrs on the lands are few, just shooting the gun ten times may knock them off, and no further work is needed.

If you are seeing cut patches on the ground, or torn up patches, check your lube, and then the powder you are using. All the Substitute powder burn at a much higher temperature, and you may need a OP wad, or filler between the powder and the PRB to keep the patch from burning. If you are using a heavy dose of FFFg powder, you may find your patches burning, and tearing. Anything above 70 grains can become a problem in some guns.

Now, if you actually are seeing little square slits in the patch where the marks of the lands appear on the used patch, you have some polishing to do.

I am a big fan, recently, or using those Green Scrubber pads you buy in the grocery store to cleaning pots and pans. Scotch brand makes them, I believe. The only caution is that you usually are going to need a jag that is one bore size smaller than your rifle's caliber. ( ex. use a .50 cal. jag to polish a .54 cal barrel; a .45 cal jag. to polish a .50 cal barrel, etc.) Jags only cost a couple of bucks, and can be ordered through the mail from suppliers, if you don't have a retailer available that carries them, but it is still something else you have to acquire, and that makes it a PITA!

Fire lapping is the next easiest way to go. Just put your lapping compound on a well lubed patch, and load a ball on the patch with the lapping compound on the outside, and fire the gun. Just seating the ball will rub the compound against the edges of the lands, and firing the ball out, will send that compound back against the lands and their edges under high pressure. It works.

The last way is to use a couple of thicknesses of cleaning patches on your cleaning jag, or , my preference, a bore brush, with the patches lubed, first, with oil, and then the lapping or polishing compound on top of the patches. Run the brush and patches down the barrel and then come back out, and use this back and forth method, with the tightly fitted patches, to polish the lands and remove the burrs. Count your strokes and every 5 or ten complete circuits, pull the patch out to examine the color of the patches, and the condition and amound of lapping compound left on the patches. The patches should turn black very quickly doing this. Add more compound if the work gets to feeling " easier " and push the patching back down the barrel and continue to scrub. I change the patches when I start seeing fraying of the edges, or splitting of the thread where my lapping compound is put. Or, if the brush bristles are poking out through both patches all around the patching, indicating that I have gotten all the real pressure out of those patches that I am going to get.

HINT: I do this work at home on my work bench. I don't need to fire a full powder load through the barrel to find out if the barrel is still cutting patches. So, Periodically, I stop, clean the barrel out of crud with alcohol, and then load the barrel with 15 grains( my .50 cal.) of FFg powder, run a PRB ball down the barrel, and then fire it into the ground in the back yard. The sound is about like a .22, only less of a crack. I have even fired them into a tree stump I had in my garage to hold my anvil, but the smoke is a problem. By shooting the shot off into the ground, I can retrieve the spent patch easily, and check it. If the lands are still cutting the patch, it will show. When only one or two lands are still cutting, I will often mark a patch at the muzzle, using a magic marker pen, then load it into the gun, and fire it, so that the recovered patch can be realigned with the barrel, and I can determine which land or lands still is the problem. Then I go back to polishing it, putting a little side pressure on my range rod to force the compound against that land or those lands as I run the patches down the barrel. I have even switched to my standard cleaning jag, with a single patch, with compound on it, to get those remaining sharp spots off. If the patches are thin, I try different patches, or double up. As long as the patches are well oiled, before the compound is put on the patches, and the double patching goes down the barrel, I can get them out. I reverse the direction of my rod after I first get the patches into the barrel, just to make the bunched up material to adjust and fit into those grooves at the back of the jag, where the rings are smaller in diameter. That makes the fabric do the work, rather than that front brass ring on my jag.

Sorry for the long answer, but it is necessary so that you know how to diagnose the source of the problem, and understand your options to fix it. Years ago, now, when I didn't own a ML rifle, yet, I met a guy at my club who had spent the prior week lapping his bore to get rid of the cut patches. He was cussing his gun a blue streak, and that is what attracted me to him. I asked him what was the problem, and he showed me patches he had saved from the last time he was at the range, and then a new patch he had just fired. He then told me about the hours he had spent polishing the land. We removed the nipple and put a light down into the flashchannel, then looked down the barrel. The lands looked smooth, polished, and no evidence of burrs. Then as I looked away from the bore, a flash of light gleamed off the rifling at the muzzle. I looked down, and noticed that the ends of the rifling, were sharp, and square at the muzzle, as if no attempt at crowning the muzzle had been down. I asked him to just push a ball and patch down the muzzle with his short starter, but leave enough patching so we could grab it and pull the ball back out. Sure enough, the front edges of the rifling had cut neat little slits around the entire ball. All he had to do was about 5 minutes of work polishing that crown and he was good to go. He was laughing when he saw me the next month. And he was very happy with how his gun was shooting, too.

 

[doublesnider]

paulvallandigham,
Thank you very much for taking the time to answer my question.
I find that the barrel is cutting my patches just seating the ball so I will try some emery cloth on a file handle. Is 400 enough?
Thanks
Martin

 

[roundball]

Martin, that's not an uncommon problem at all for a new barrel...it's just sharp edges on the ends of the lands.
Just shooting it will take care of it no time by the repeated seating of patched balls, and that way there's no risk in screwing something up by tinkering with the crown, which is just about the most critical accuracy related location on a barrel
:thumbsup: