Home Forums Hunting & Shooting Hunting Rifles Hand lapping a barrel?

I suppose I could have put this in a different section but seeing all I own are "hunting rifles" this is were it is posted. On the topic of hand lapping a new, or used for that matter, barrel what is the proper procedure. I have never done it to any rifle I own and have had pretty good accuracy with every rifle so far. Just curious as what it involves and what kind of results to expect. Thanks.

Ya pour a molten lead lap on a jag similar to a cleaning jag, coat it with abrasive and push and pull through the bore. Bad news is that this procedure bells both ends of the bore, which ain't no problem with a new barrel because chambering it removes the bell at one end and cutting the blank back to the desired length before crowing removes the other.

Some guys, me included, wrap a patch around an undersized bronze bore brush, spray it with Kroil, and rub JB Bore Paste into it and work that back and forth through the bore. It ain't a real lapping, but it does clean up the fouling left behind and smooth things a little. The patch will never come out clean, because the abrasive turns black as it works. Don't over do it.

You can smooth up a really rough barrel by using successive grades of fire lapping bullets. A worn and checked throat can be smoothed up using David Tubb's Throat Maintenance Kit, a fire lapping bullet with fine abrasives. Check here: www.superiorshootingsystems.com/RELOADING-FINAL_FINISH.html
or www.superiorshootingsystems.com/RELOADING-TMS.html

The best solution is to purchase a lapped barrel in the first place. Look for barrels made by the cut rifling process to be the best bet, button rifled barrels the second choice. Most are drilled, reamed, lapped, rifled, stress relieved (button rifled barrels) and lapped again. I use Shilen, Pac-Nor, Hart, Brux, and Kreiger barrels, there are many more fine barrel makers out there.

Plus 1 on the firelapping. This is how I 'break in' a barrel or fix one that is badly worn. I have managed to really improve the accuracy of several with this method.

You'll never improve the finish, imparted upon the barrel bore by the barrel maker in his shop, by hand lapping the bore of a completed rifle at home. In addition, it is impossible to evenly remove material and/or straighten out material from a bore i.d. by running a patched jag coated with compound through the bore. A bad barrel will always be a bad barrel, and a good barrel will be a good barrel out of the shop.

You'll more than likely find better results by playing with bedding forend pressure points to find consistency from a less than good barrel such as from many factory rifles. You cannot make chicken salad out of chicken poop:) Do your best to maintain your barrel to prevent rust and to keep under control any excessive build-up without being aggressive as to rounding the edge off rifling and/or damaging the crown. The barrel is what it is and will only become worse if you are aggressive.

Best:)

My experience differs in that I have taken well bedded but rough barrels and made them much better in several instances. One was a very old 250/3000 with a rough bore the other a Butler creek barrrel in 22LR whose groups shrunk by fully 1/2 after firelapping. This is probably somewhat true, however, with high end custom barrels although mild firelapping is still my preffered method for breaking in.

There is a great article in this months Rife Shooter magazine about this. David tubb and other target shooters have been doing this for years with good results.

Take fire lapping with a grain of salt. Even David's system carries a disclaimer on using his final finish in a custom barrel lapped by the maker or in a factory barrel that shoots good groups as using the fire lapping process will degrade the barrel. Using it in a barrel that was neglected and allowed to develop multiple layers of excessive fouling will more than likely knock down the speed bumps in the barrel i.d., but many such barrels get this way in the first place from complete neglect and/or improper maintenance. As to using it in barrels that are poorly made, it cannot hurt too much and more than likely will only have most of its effect in the throat area.

In terms of a good barrel, don't overheat with rapid firing and keep copper build up in check while allowing the barrel i.d. to burnish with a hard coating of carbon fouling. A good barrel has a micron finish conducive to allowing a burnishing of carbon fouling which reduces sticking of jacket material. This is done without artificially degrading, eroding, or rounding the steel of the barrel i.d. itself. Otherwise, you'll chase your tail in circles while increasing the rate of wear on the barrel.

Best:)

Hand lapping isn't something that can be done on an installed barrel, it has to be done to the barrel blank before chambering and crowning so that the ends can be removed in the crowning and chambering process.

Fire lapping is the only real option and I'd only do that to a barrel that I'd exhausted all other options with. I'd do it if I'd given up hope and was prepared to buy a new barrel if it didn't work. It's one of those "last resort, I've got nothing to lose because this thing shoots like krap" type of things.

Good to know and thanks. All my rifles shoot sub MOA. Not sure if it's due to luck or treating them well. Maybe both. I've heard all sorts of methods to improve accuracy so I was just curious about "lapping a barrel" I was a machinist for a few years before my current occupation and have used "lapping" compound to seat valves in engine heads once upon a time. So, it caught my interest when I had seen it mentioned. Thanks for the info fellas.

Results of hand lapping at home..Remington LTR .308...



First days shooting once sighted in:



With handloads:



Friends gun..same exact gun as mine...I did the lapping on his also...as well as a dozen of my friends guns...

300 yards...



800 yards..




LTR .223 bought used but unfired. Shot before lapping with 75 grain Hornady TAP ammo...best group was .75" at 100...this is after lapping...

All targets 300 yards...

.69"



[img]http://i17.photobucket.com/albums/b77/RJM52/Long%20Range%20Shooting/GB040608005.jpg[/img]

[img]http://i17.photobucket.com/albums/b77/RJM52/Long%20Range%20Shooting/GB040608003.jpg[/img]

I have another target downstairs but not yet photographed at 600... 1.9" ctc...

Very simple to do and talks no special tools. Figured out how after the barrels on two Ruger #1s rusted on me while cleaned and in a gun safe...no other gun showed any rust anywhere but the bores on these two just GREW rust. After lapping the .22-250 #1B went from .75 moa to .4 moa. The .375 H&H went from .75 moa to clover leafs...

I now do all my long guns and some of my handguns.

Bob

Bob, what is your technique?

The problem with real lapping with a lead lap is that you're removing metal from the lands and grooves. The goal is to remove tool marks and make the diameters (groove and land) exactly consistent all along the barrel. By the time that's done a barrel which was finished to final size will likely be way oversize. Polishing without changing the barrel dimensions appreciably is another matter.

The only rifle I've lapped was my 700 Classic .250 Savage. It fouled teribly. First few 3 shot groups would be great, but accuracy was gone by the 5th group. I tried moly coating, but accuracy still went way south after 40-450 rounds. JB gave me the instuctions: wrap a patch around a bore brush, coat with 220 grit valve lapping compound, and start strokoing for about 100 strokes (50 back-and-forth motions). Clean it out, then finish with JB compound, 30-40 strokes. It now maintains .4" groups and smaller with 75gr Vmax and 100gr SP bullets for an indeterminate number of rounds,as I clean it yearly. Cleaning is now done with a few wet patches (Shooters Choice+Kroil) and a few dry.

Translated.. all you are doing is wearing out the barrel quicker...

load development can run into a couple of hundred rounds which will remove the tool marks..

most gunsmiths I know personally highly recommend AGAINST hand lapping a barrel..

After about 300 rounds, I got tired of fighting with the thing. It seems nighthawk's last sentence hit s the mark; I probably polished rather than actually lapped. Whatever, it worked.

I guess first I would have to ask exactly what everyone feels the difference between "lapping" and "polishing" is.

Bob

I've been waiting on your answer RJM.

My definition of lapping is using a cast lead lap to even out bore diameter inconsistencies and machining marks with lapping compound.

Polishishing is any other method. JB, Flitz and even lapping compound applied with a mop or brush or anything besides a cast lead lap.

Fire lapping, well we know what that one is.

What did you use?


fish head

This was sent by Gale McMillan over a decade ago and it still applies today. This is in the context of a rough barrel bore. You could ruin a custom barrel if you attempted to alter the bore finish imparted by the maker, and you could ruin a good barrel if you attempted to lap the bore without a proper lap. It is impossible to lap a barrel evenly without the use of a poured lap as you would remove material unevenly and would round the rifling causing excessive wear in the areas you do not want to alter. Attempting to lap an installed barrel, would in addition, wash out the muzzle and breech ends. This is Empirical data collected from years of experience via top-end barrel makers and not from the use of a placebo effect. Quite a number of rifles such as the LTR noted in this thread will shoot very small groups when properly broken-in with a layer of hard carbon burnished upon the bore. Quite a number of the same rifles will open up if copper jacket material is allowed to stick and build upon itself. Simply removing this build-up will restore accuracy having nothing to do with home-brewed lapping. Quite often people think they are lapping when in reality they are only cleaning aggressively while accelerating wear.

From Gale reference a rough barrel:

�Run an oily patch through the bore first. To make a lap you can use an old cleaning rod. Wrap masking tape around it just behind the jag until it fits into the barrel tightly and will hold the rod in place when the barrel is held vertically. Pull it back into the barrel about 6 inches from the muzzle. Heat a lead ladle full of lead until it is very hot, it can be turning red and work well. Hold the barrel by the muzzle with your hand 6 inches below the end and tilt the barrel at an angle so that any overflow will miss your hand as it falls. Pour the lead as fast as you can without spilling so that it doesn't cool as it runs down the barrel. When the barrel is filled, let it cool, and bump it out about an inch and then carefully trim the end off so that it can be drawn into the barrel. Bump it out about three inches and pour oil all over it. At this time put masking tape at the breach end so that you can use it as a gage to see how far to push it out, then measure the barrel and when you have pulled it out the length of the barrel put another round of masking tape so you can tell how far to pull with out pulling it out of the barrel. Push it out of the barrel and oil it and put a very small amount of lapping compound on it and draw it through the barrel a few strokes and add a little more. It is better to go real slow with the amount of lapping compound rather than get the lap stuck in the barrel. Keep oiling the lap and charge it when it gets easy to pull. Its all a matter of feel. Use 220 grit clover leaf non imbedding lapping compound. It goes without saying that you hold the barrel in a vice while lapping. Lap it full length until the lap frees up and charge it with a little more compound. Lap it a few strokes and remove the lap and clean the barrel and look at it. You don't want to remove a lot of material, Just enough to clean it up. Clean with solvent and brush when finished. When using a 6-8 inch poured lead lap on the end of a cleaning rod to lap with, it will indeed increase the diameter at the point at which you change directions, this is almost always the breach and the muzzle. You never lap an installed barrel except as a last resort!� - Gale McMillan

This is an excerpt from an article written by Dan Lilja on barrel fouling and break-in around a decade ago. It also applies here:

�Makers of custom hand-lapped barrels spend a lot of time achieving the internal finish that they require. We've experimented with different techniques and products and have settled on what we believe gives us the best finish. We strive to get a smooth uniform finish without losing the geometry of the rifling -- that is, keeping the lands sharp-cornered and crisp. And though it may surprise some, lapping to a finer finish will result in an increase in fouling. A barrel can be too smooth.

It is important to break-in a barrel though. The jacket material must be removed after every shot during the initial few rounds. If this isn't done the areas of the barrel that fouled will tend to pick up more fouling and it will build on itself. It is important to get a layer of powder fouling on top of the lands & grooves. This hard deposit will prevent the copper from stripping off the bullets. However, if the internal finish of the barrel is too rough the barrel will never be completely broken-in and fouling will always be a problem. Some barrels can't be broken-in.
A similar phenomenon can exist if the shooter uses an abrasive-type cleaner too often. The abrasives are very effective at removing all traces of both powder and jacket fouling. I mentioned that a barrel can be too smooth. The abrasives can get a barrel too clean as well and in effect the shooter is rebreaking-in the barrel again every time he cleans. This can end up in the dog-chasing-his-tail scenario. The shooter thinks the barrel is a fouler, as evidenced by the copper accumulations in the barrel. He works hard at removing the copper, resorting to using an abrasive cleaner. But when he does he removes the desirable layer of carbon fouling left by the powder and exposes fresh steel ready to grab some more copper off the bullet on the next shot. The cycle repeats itself. Like the dog the best way out is to go lay down and take a nap.� - Dan Lilja

My advice would be to refrain from running the barrel temps through the roof from excessive rapid shots. Keep jacket fouling in check and allow the bore id to burnish with a hard layer of carbon fouling. Maintain the barrel to prevent rust without stripping the bore down to bare steel. Use the least aggressive methods possible to keep fouling in check. Shoot the gun and allow the bore to break-in without inducing accelerated wear from aggressive means. If you feel the need to lap a rough bore, do so correctly by pulling the barrel.

Best:)

I've had very improved results by firelapping, accuracy and fouling-wise from factory barrels.

Step 1: Totally clean and degrease the barrel

Step 2: On a very tight patch apply fine valve grinding compound and preferably use a bore guide from the breach end of the barrel. The patch must be very tight fitting but move smoothly so you can "feel" the barrel.

Step 3: There is no standard number of passes made through the barrel. The patch should be changed every 10 strokes or so. The cleaning rod should be marked so that the patch pusher just begins to exit the barrel before it is pulled back through to the chamber lead. If the patch is tight and running smoothly one should be able to "feel" any tight or loose spots in the barrel. I have had very few barrels with excessive tight or loose spots but for those few that I have just work the patch back and forth a few times on the high spots...there isn't really one can do about the loose spots using this method. Then change the patch and continue until one can feel a smooth and even finish. Sometimes I also end up totally cleaning the barrel again during this phase inspect the progress and continue.

Step 4: When the barrel feels smooth again totally clean and degrease. This step is much like Step 3 but in this phase the polishing compound is much finer. I was given 30 and 40 micron diamond lap from a friend in the computer industry. A small squeeze bottle will last a life time. This is what I finish the barrel with. Same as above on a very tight patch the only difference is the last few passes are done only in one direction and right out the muzzle. Clean and degrease and it is ready to go.

I can usually do a barrel in 1/2 an hour. The results are above.

Have a friend who used the shoot, clean, shoot, clean, shoot , clean.....method and it worked great... His 700V .308 went from .6 MOA to .2 but it took him a month of shooting and cleaning to accomplish what I did with no wasted ammo in 30 minutes.

I had the above posted .308 LTR for about 6 years...during that time the barrel was cleaned three times, the last time was just before I sold it. There was never any copper fowling observed growing in the bore...just black from the powder. Never any rust. It would also put the first cold shot on the money no matter the range. Once cleaned it was 3-5 shots before it would go back to zero. The same was true for the .223 LTR and a .223 700V that my neighbor now proudly owns.

As they say...YMMV.

Bob

I have been shooting for various reasons for most of my 72 years and I've yet to see a .2 factory rifle. I don't care what you do with it! I've heard about a whole bunch in cyberspace though; some even with store bought ammo. The trend now seems to be anytime you fire more than one shot at a target, it's a group. I guess next we'll start hearing about .308 or .243 groups. Or, more properly speaking, .00 groups.
Anyone can fire one good group with any rifle and combo of ammo, especially if you're only firing 3 rounds, but I still subscribe to the NRA standards of the agg of five, 5 shot groups determine
what a rifle can do.