From: email@example.com (Russ Kepler) Subject: Re: Lapping a Barrel Organization: /usr/lib/news/organi[sz]ation In article <firstname.lastname@example.org>, Phillip R. Johnston <fz671@cleveland.Freenet.Edu> wrote: #I have seen and read several hints in gun book articles about #lapping or fire lapping barrels but nothing in any detail. Is #this something that should be done or is it something that #is outdated nowadays? Could someone please respond on how to #do it and the gains acheived by doing it. Barrel lapping used to have to be done on a production line to get a good barrel, at least until the introduction of button rifled barrels. Many custom barrels are still lapped for the highest precision. Traditional lapping is done by creating a lead plug that fits the bore as precisely as possible (typically by pouring it in the barrel over a plug. The lap is removed partially from the barrel and lapping compoubd applied. The lap is psuhed and pulled through the barrel until a consistent pressure is felt though the action. It is often necessary to pull the lar from the barrel and to make a new one, and it's always necessary to clean when changing grits. Properly done a lapping will make a barrel consistent to within a few tenths (.0001"), typically 1/10000". In addition the barrel will be easier to clean and can run for more shots without bad fouling. Fire lapping is the lazy man's barrel lapping, and some say that it does as good a job. Nothing will replace a good custom barrel, but firelapping will improve most factory barrels and make them easier to clean and fire more consistent groups. Fire lapping consists of embedding lapping compound on the driving surfaces of the bullet and firing the bullet through the bore. After a small number of shots (5-10) the barrel is typically cleaned and you progress to the next finer grit. I believe that LBT sells only a couple of grits, NECO sells 4 with the final being a 1200 grit. Fire lapping kits are sold by both LBT and NECO. The NECO kit come with 4 grits and a couple of hardened plates for embedding the lapping compound into bullets. NECO will also sell kits of loaded ammo for firelapping a particular caliber, along with lead slugs for a before and after comparison of the barrel. -- Russ Kepler posting from home email@example.com Please don't feed the Engineers
From: firstname.lastname@example.org (Doug White) Newsgroups: rec.guns Subject: Re: Fire Lapping and special electronic micrometer Date: 20 Mar 1997 09:41:50 -0500 Keywords: In article <email@example.com>, Norm Johnson <firstname.lastname@example.org> wrote: ## I had to buy a special electronic micrometer just to measure the > > #changes in my bore. # #Details please? OK, here are all the gory details of my lapping/slugging process: Results of 'Fire-lapping' Krieger .308 Winchester Barrel Measurements were taken using a Mitutyo Model 293-721 Electronic Micrometer, which has a resolution of 0.00005" (50 millionths), and an 'Instrumental Error' of 1/3 micron (~40 millionths). The quantization error is +/- one count. Used carefully with a micrometer stand to prevent heating the micrometer from the hand, the micrometer appears stable enough to resolve differences down to the resolution. Comparison of measurements from day to day may vary due to temperature changes in my basement, but they were fairly consistent. Measurements late in the process were also more consistent, probably due to improved technique. The micrometer also has a ratchet, which helps apply consistent pressure to the object being measured, which is important when you are using a soft lead slugging bullet. The slugging bullet was measured across two axes, and showed a slight eccentricity, so both readings are listed. The average dimensions and standard deviations are shown for each axis. The slugging process was done in accordance with the instructions in the NECO Fire Lapping Kit. 'Slugging' Results Before Lapping: BREECH MUZZLE 0.30690" 0.30705" 0.30700" 0.30710" 0.30690" 0.30695" 0.30700" 0.30710" 0.30695" 0.30700" 0.30700" 0.30705" -------- -------- -------- -------- Ave 0.30692" 0.30700" 0.30700" 0.30708" Std Dev 0.00003 0.00005 0.00000 0.00003 Comments: A tight region was detected by feel about 2/3rds of the way from the muzzle to the breech. After this point, the bullet was noticeably harder to push, and the resistance remained fairly constant the remaining distance to the breech. The readings indicate a taper of ~ 80 millionths of an inch from the breech to the muzzle on both bullet axes. This may be the result of the barrel 'relaxing' when the OD was turned down to taper slightly from the breech to the muzzle. 'Slugging' Results After Lapping With 10 Rnds of 220 Grit: BREECH MUZZLE 0.30690" 0.30705" 0.30695" 0.30700" 0.30695" 0.30700" 0.30700" 0.30705" 0.30695" 0.30700" 0.30695" 0.30705" -------- -------- -------- -------- Ave 0.30698" 0.30702" 0.30697" 0.30703" Std Dev 0.00003 0.00003 0.00003 0.00003 Comments: The tight spot was still present, but not as much as before. The taper had been reduced down to 10 to 40 millionths of an inch, depending on the axis. The difference in the muzzle measurements from before and after may be the result of variations in the zero of the micrometer (temperature?). 'Slugging' results after lapping With 12 rnds of 400 grit, followed by 12 Rnds of 800 grit and 12 Rnds of 1200 grit: BREECH MUZZLE 0.30695" 0.30705" 0.30700" 0.30700" 0.30695" 0.30700" 0.30700" 0.30705" 0.30695" 0.30700" 0.30700" 0.30700" 0.30695" 0.30700" -------- -------- -------- -------- Ave 0.30700" 0.30702" 0.30695" 0.30701" Std Dev 0.00000 0.00003 0.00000 0.00003 Comments: The tight spot had disappeared completely. The taper seemed to have reversed, and now the measured muzzle dimensions are slightly smaller than at the breech by 50 millionths across the small axis of the bullet, to 10 millionths across the large axis. Many of the differences measured are smaller than the accuracy limits of the micrometer, and may have little real meaning. If you believe the readings as gospel, the bore at the muzzle got smaller after each test. This is clearly wrong, but I believe the measurement of taper (comparing measurements taken on the same day) has some validity. In any event, there WAS a significant improvement in the subjective uniformity felt when pushing the slugging bullet through the barrel. Besides, I had a lot of fun doing the measurements, and the barrel is now MUCH less prone to fouling, which was the main result I wanted.
From: email@example.com (Doug White) Newsgroups: rec.guns Subject: Re: Good barrels for Rem 700 in .308? Date: 13 Feb 1996 15:59:25 -0500 In article <firstname.lastname@example.org>, Don Bledsoe <email@example.com> wrote: <snip> <Doug I certainly do not dispute your results but using the clean and <shoot, clean and shoot, process and then not using it has not shown any <difference in the barrels I have been using (Lilja and Krieger). The <clean up is no different on a so-called broke in barrel as opposed to one <that was shot 10 rounds, cleaned, shot another ten rounds, cleaned, etc. <I try to clean every ten rounds when I can, regardless whether I am <shooting a new barrel or not. Naturally that isn't always possible such <as in a match. < <Be that as it may, there was still no description in your post as to what <the so-called break in process of shoot one, clean, shoot two, clean, etc. <actually does to a barrel as far as I can tell. You did indicate that you <felt this process is similar to fire lapping but I do not understand how <you reached that conclusion. Do you clean with abrasives between these <first shots? It would seem to me that shooting through an uncleaned <barrel will be more like a fire lapping process than one that is cleaned <ever other round or so. The accumulated debris from priming compound, <powder fouling, etc. would make a better lapping compound than and bore <solvent will? The Springfield was cleaned with a good copper solvent, like Shooter's Choice, no abrasives. The 'theory' is that you want to keep the bottom of the pits and scratches free of copper and grim until you've had a chance to burnish some of the steel down into them. I don't know if there is any hard evidence to support this effect or not. Like so many problems with fussy rifle shooting, it's nearly impossible for mere mortals to come up with decent controlled experiments. The true fire lapping process with abrasive coated bullets is a little different from firing down a dirty bore. You've got a much better chance (particularly with a soft lead bullet) of the abrasives _polishing_ the bore, rather than getting hammered into it with a harder copper bullet. <How did you measure a ".00005" taper" in your barrel? This wasn't easy, and took some practice. I used a Mitutoyo electronic micrometer with a ratchet thimble and a mic stand (heat from holding the mic will effect readings at this level). The absolute accuracy of the mic isn't good enough to do this, but I convinced myself after taking lots of measurements that fairly accurate differential measures were possible. As it was, I had to average several readings. You put a soft slug in the bore, and 'upset' it with two cleaning rods to fill the grooves. You then carefully push it out of the bore and measure it. You do this at both ends of the bore, and compare. Once it became apparent that the bore was funnel shaped (larger at the muzzle), I'd measure the muzzle end, and then run it back toward the breech and measure it when the slug came out. The result was fairly repeatable, and showed a definite (but tiny) taper. It also showed that one pair of grooves were slightly deeper than the other. The taper was expected, because the exterior of the barrel had been turned with a slight taper toward the muzzle. This apparently relieves stress in the bore, and the barrel tends to open up where the metal has been removed. Even if you don't believe the measurements (which are on the edge of believablity, I agree), when running the slugging bullet through the bore, I could FEEL the bore getting tighter, and there was even a spot where it was significantly tighter than at the breech. When I had finished the firelapping, the resistance on the slugging bullet was quite uniform for the full length of the bore. A Krieger barrel is going to be pretty good to start with, so I don't know how much I improved it on a practical level. I certainly had a good time experimenting with it and the firelapping process. The Springfield that we broke in using the regular shoot and clean method IS definitely easier to clean than ones that were not done in this manner. Unfortunately, this could easily just be the difference between a barrel rifled with fresh tooling vs old. You never know. I think it helped, and I had a heck of a fun day doing it (although after 120 rounds with a straight stock and a steel butt plate, I was a bit sore the next day). Doug White
From: Norm Johnson <firstname.lastname@example.org> Newsgroups: rec.guns Subject: barrel lapping Date: 19 May 1997 12:43:33 -0400 Gentlemen and Fair Ladies, # On 9 May 1997 13:26:49 -0400, Michael Stern <email@example.com> wrote: ## #I just acquired a .22 Hornet rifle, new. The gunsmith tells me to shoot ## #a few rounds, cleaning frequently between shots, then bring it to him to ## #lap the barrel. He kinda explained it to me, and it sounded like a good ## #idea, but can someone give me details as to what lapping is, and why I ## #should (or should not) have it done? Thanks. ## # ## I have used firelapping with some success. Sometimes it worked to ## increase accuracy, and sometimes it did nothing. It never hurt ## anything. I have a friend who hand laps all his guns, and they all ## shoot very accurately. Gale McMillan wrote: #If he was thinking of lapping it by conventional ways don't let him. He #may have the best intentions but you never lap an installed barrel #except as a last resort! Reason being that a lap cuts more at the point #where direction is change resulting in washing away the throat and #muzzle if he is talking about fire lapping then he is looking to pick up #a few bucks and will do more harm than good to your new rifle. While I #personally doubt it, there may be a point made as a last resort case on #an old rifle where the effect of Choke bore effect of fire lapping is #the lessor of two evils. Look at a barrel that has been fire lapped and #you will see why I don't recommend that you let him at your new rifle. #Any type of lapping removes material so why would you think a new barrel #could benefit by changing the bore dimensions and making it larger at #the throat than at the muzzle? Having read similar comments over the years, but not having done any closely monitered lapping experiments, I decided to risk my virtually new .357 Herrett Contender barrel in the interest of a little quantitative information. I have just finished the first step of this procedure. This bore measured .3566" at the outset, and was selected because it copper fouled so rapidly and I wanted a smooth bore for cast bullets. I used LBT bore lapping compound charged dead soft HBWC bullets. These were loaded over 5.6 gr. of 700X for 700-800 fps target loads, all of which shot very well as practice loads. The bullets were set out in the case so that closing the action did the final bullet seating. I swabbed out the chamber at about each twenty rounds, although I could not really detect any appreciable compound build up. Over four outings I fired 350 rounds which is considerably more than is normally needed to smooth up a bore. The bore is now .3576-77" at the muzzle and .3579-80" at the breech. This 2-3 ten thousandths choke bore is considered by many to be of some benefit. There is certainly no washing away of the throat, the origin of the lands remaining clear and sharp. Excessive bore diameter increase and throat erosion, I suspect, is from improper lapping procedures. Perhaps those who have experienced it used valve grinding compound or other abrasives that were too fast cutting. Since this is a lead bullet shooter, I was not concerned about the possibility of an enlarged bore as the cast bullets will be made to fit the bore anyway. I have only been able to measure about 3 T/C barrels which have had relatively tight .3565" or so bores. I suspect that this is because they shoot a lot of pistol bullets that run almost exactly that diameter. Commercial jacketed rifle bullets are generally .358". However, this is a good example that those who worry that a bullet is a couple of thousandths over nominal bore diameter, have no real concern. My .357 Herrett and a .35 Remington seem to handle both well. Fire lapping, if done with some care and prudence, is not likely to have negative results and may improve conditions considerably, depending upon what one is attempting to accomplish. It, however, is not a cure for bad loading procedures, poor (lead) bullet fit, etc. God Bless! Norm
From: Kelly McMillan <firstname.lastname@example.org> Newsgroups: rec.guns Subject: Re: barrel lapping Date: 20 May 1997 11:08:25 -0400 Norm Johnson wrote: > ... The comments about creating a larger diameter at the muzzle and breach had to do with traditional methods of lapping, not "fire lapping" as you used in your evaluation. 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. Kelly -- McMillan Fiberglass Stocks Inc. "Molding the Way America Shoots" 21421 N. 14th Ave Suite B Phoenix, Arizona 85027 (602)582-9635 http://www.mcmfamily.com
From: Doug White <email@example.com> Subject: Re: Break In? Organization: MIT Lincoln Laboratory In article <firstname.lastname@example.org>, <Sang.Shin@lambada.oit.unc.edu> # Are there any particular break in procedures to follow when firing a gun # for the first time? # # sang # # -- # The opinions expressed are not necessarily those of the University of # North Carolina at Chapel Hill, the Campus Office for Information # Technology, or the Experimental Bulletin Board Service. # internet: laUNChpad.unc.edu or 188.8.131.52 In a word, maybe. For a .22 rimfire of any flavor, and most handguns, I'd say go ahead and shoot it. Centerfire rifle is a different story. There are several procedures around for breaking in a CF rifle. The idea is to polish the bore as much as possible before it has a chance to collect a lot of copper fouling. It can make an enourmous difference in how easy it is to keep clean in the future. There are 2 ways I've done this: 1) Fire 1 shot, clean thoroughly. Fire 2 shots, clean thoroughly. Fire 3 shots etc. Proceed until you're up to 15 shots. What I found was that the amount of grunge stuck in the bore after the last 15 shots was much less than what was stuck after the 1st shot! The result is a rifle that is much easier to clean, and requires cleaning less often. This was done on a re-barreled Springfield O3-A3. 2) The more complex, expensive, and time consuming process is called 'fire lapping'. This involves firing abrasive coated bullets down the bore in increasingly finer grits. It is all the rage amongst the benchrest crowd. There have been a number of articles in 'Precision Shooting' full of success stories with this process. A company called NEECO sells kits to do this. If you enjoy tinkering and reloading, you can get a kit for about $80 with instructions, bullets, and abrasives. Or you can spend $130 to get pre-loaded ammo. I used the do-it-yourself kit on a custom .308 match rifle. In addition to polishing the bore, it can remove minor manufacturing errors in the rifling, and has been known to produce remarkable improvements in accuracy. I started with a Krieger barrel, so I don't think there was much more accuracy to be had, but it definitely helps with cleaning and fouling. If you're doing it right, you 'slug' (measure) the bore between steps to monitor your progress. I did remove a slight (0.0001") internal taper in my bore, and ironed out a tight spot in the middle that I could feel while slugging, but couldn't really measure. If you want to know what you're getting into, NEECO sells their fire-lapping manual for $9. Unfortunatley, I don't have an address or phone no. here, but they advertise in Precision Shooting and Shooting Sports USA. Doug White MIT Lincoln Laboratory
From: Doug White <email@example.com> Subject: Re: Break In? Organization: MIT Lincoln Laboratory In article <firstname.lastname@example.org>, <email@example.com> writes: # In article <9312161017.AA17076@ll.mit.edu>, # Doug White <firstname.lastname@example.org> wrote: # #2) The more complex, expensive, and time consuming process is called 'fire # # lapping'. This involves firing abrasive coated bullets down the bore # # in increasingly finer grits. It is all the rage amongst the benchrest # # crowd. (snip) # # A company called NEECO sells kits to do this. If you enjoy # # tinkering and reloading, you can # # get a kit for about $80 with instructions, bullets, and abrasives. Or # # you can spend $130 to get pre-loaded ammo. I used the do-it-yourself # # kit on a custom .308 match rifle. In addition to polishing the bore, # # it can remove minor manufacturing errors in the rifling, and has been # # known to produce remarkable improvements in accuracy. I started with # # a Krieger barrel, so I don't think there was much more accuracy to be # # had, but it definitely helps with cleaning and fouling. If you're # # doing it right, you 'slug' (measure) the bore between steps to monitor # # your progress. I did remove a slight (0.0001") internal taper in my # # bore, and ironed out a tight spot in the middle that I could feel # # while slugging, but couldn't really measure. # # I bet Krieger will be delighted to hear about people shooting wads # of sandpaper down his hand-lapped bores :) I wouldn't firelap a # custom barrel for love nor money (well, maybe for ENOUGH money :) # To firelap a *chambered* rifle bore, especially one produced by # a top barrelmaker, is an expensive form of Russian roulette. # # -Toby Bradshaw # email@example.com I will be the first to agree that this is a scary process. After taking a look at the 220 grit abrasive I nearly had a heart attack. Having been through it once, I will do it to any rifle I buy in the future. I carefully monitored the process by slugging the barrel after each firing session, and the bottom line is that it did remove noticeable irregularities in my bore. Just because a barrel is lapped by the manufacturer doesn't mean it's perfect. My barrel has a taper turned down from a cylindrical blank. I was told that when the metal is removed near the muzzle, residual stresses can be relieved that let the barrel expand slightly. This produces a funnel shaped taper with the wide end at the muzzle, which is definitely not good for accuracy. Depending on how well the barrel is stress relieved by the maker, and how much metal is removed, the effect can be very small. When I first slugged it, that is exactly what I found. Both the taper and the tight spot are gone now. I admit that some of this may be advertising hype on the part of M. Martin, but _I'm_ convinced. I believe the Canadian Palma team is also convinced. Not because of any claims of accuracy enhancement, but because they can go many more rounds before fouling affects their accuracy. The process is a lot of work, and definitely not for everyone, but I wouldn't knock it 'til you've tried it. Incorrectly done, I'm sure you could trash a good rifle. The same can be said for careless reloading and cleaning. Doug White MIT Lincoln Laboratory
From: gale mcmillan <firstname.lastname@example.org> Newsgroups: rec.guns Subject: Re: Barrel lap Date: 10 Aug 1997 00:17:55 -0400 RDM1911A1 wrote: # I recently acquired an older Mauser with a pretty dark bore. # After de-gunking the entire piece I found that the bore was not # all that bad. I went after the bore with a worn out stainless steel # brush in 38/357 dia.& some good penetrating oil. I got all the rust # out but looks like it could use some lapping to unifom things a bit. # Someone told me I could make a lap by stuffing a piece of greased rag # about 2" down the muzzle, insert old brush,,jag,or patch holder and fill # her up with molten lead. My question is should the bore be dry,lubed,or # coated with something like the mold release agent you spray on bullet # molds before you pour in the lead.My bullet molds always released the # bullets best when they were totally oil free but I think the lap may # solder # itself to the irregularities of the bore. # Any help or thoughts would be greatly appreciated. # # Rod # RDM1911A1@aol.com # # To err is human, but to blame it on someone else is even more human! Run an oily patch through the bore first. Then roll masking tape around the rod a couple of inches below the brush till it will just enter the bore but won't slide out on it's own. Remove all the bristles from the brush. Position the rod so that the tape is 6 or 7 inches from the muzzle. Hold the barrel on about an 80 degree angle and pour full of molten lead.( pure lead) If you spill any lead it will miss your hand due to the angle. Place the barrel in a vice but do not tighten very tight as it will deform the barrel and you will lap a ring in it. Bump the lap out an inch and with a sharp file trim all the material that is bigger than the bore away. Oil it and pull it back and forth in the bore till it is free. Push it about 3 inches out of the bore and charge with a very small amount of 180 grit lapping compound. 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.
From: Norman Johnson <email@example.com> Newsgroups: rec.guns Subject: bore polishing Date: 10 Jan 1998 17:32:28 -0500 Robert, #Any help...Sako rifle...7mm mag...barnes and nosler bullets are #used...average groups with hand loads are 3/4 inch at hundred yards. #The rifle has had about two hundred rounds shoot through it. My concern #is that the bore retains alot of copper fouling after shooting session. #Would polishing the bore help at this point, if so any information on #how and what to buy would be helpful. The two "accepted" methods of lapping the barrel have been 1.) shooting lapping compound coated bullets and 2.) using a coated lap (usually made from a bullet or lead slug) on a rod. Both are sort of messy but the first is easier and does not require that special touch required to keep the rod (which gets coated with compound) from touching the muzzle or chamber. Both the lap and the shooting methods polish the grooves as well as the lands; but especially they polish the sides of the lands. The roughness of the sides can tear away at the bullet, allowing gas cutting and subsequent leading. Close inspection of a lead bullet where gas cutting is present will nearly always reveal that it started in that area. In some revolvers, the area of the bore directly adjacent to the forcing cone where the barrel is screwed into the frame is small- er than the rest of the bore. This damages the bullet much the same as does an undersized throat and, unfortunately, is a very common occurrence. Lapping will take care of this problem at the same time, removing that and any other tight spots in the bore that may be present. It has the added advantage of providing a very slight taper to the bore for excellent cast bullet shooting and will do a great job of minimizing leading. Be careful what you use for lapping compound. The LBT lapping compound is a very fine screen while Clover grinding compound is much more coarse and not suitable. The only thing that I would feel comfortable with other than LBT type products is toothpaste which has been used to smooth up revolver actions. It is ever messier. LBT bore lap kits come with one or two lapping compounds, depend- ing upon how Veral Smith feels that day I guess. His ad that I responded to said there were two and I received one only. I sent an inquiry and got a second one (jar) with a note that he had determined that only one was needed and that he had dropped his price a couple of bucks accordingly. That was a number of years ago and a small jar lasts forever. Lapping works because a very hard cutter medium is used to do the work. A soft material (leather in the case of a razor strop, lead in the case of a barrel lap) is used as a carrier for the cutting (lapping) compound. For bore lapping using the shooting method (called fire lapping by some), the slug is charged with the lapping compound. The general procedure is to use a piece of very flat stock, such as a steel plate, glass plate or formica covered board. Smear it with a relatively thin coat of the lapping compound. Then using another flat plate, roll unlubricated bullets between the two to charge the bullets with the compound. If the grease groves are not filled in this process, fill them by hand. Absolutely full grease grooves are not essential but do get some compound into them. This is very easily accomplished using ones fingers. Again, Veral Smith of Cast Bullets Technology has the proper stuff for $10 or so. Veral Smith sells lapping compound and has detailed instructions in his book "How To Make Cast Bullets Shoot Like Jacketed" recom- mending its use which I know works very well. It has made no significant dimensional difference in the barrels except in the tight spots. His book says that 200-500 rounds is not too many - I agree. His lapping compound seems MUCH finer than valve grind- ing compound. The Fouling Shot (now called The Cast Bullet) is the official journal of the Cast Bullet Association. CBA is a world wide group of about 1800 people that is dedicated to the advancement of cast bullet shooting. This is a really worthwhile group that is often years ahead of the popular gun magazine writers in many facets of shooting (not necessarily limited to Cast bullets). God Bless! Norm
From: Gale McMillan <firstname.lastname@example.org> Newsgroups: rec.guns Subject: Re: Q: Barrel lapping How-To Date: 2 May 1999 12:07:27 -0400 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 about 20 degrees 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 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 so 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 with out saying that you hold the barrel in a vice while lapping. Clean with solvent and brush when finished
From: Gale McMillan <email@example.com> Newsgroups: rec.guns Subject: Re: Bore Polishing Date: 9 Apr 1999 16:34:39 -0400 Do not use diamond paste in the barrel. It will embed in the steel and become a lap. Use Clover Leaf brand lapping compound 180 or 220 grit on a lead lapp.