Author Topic: Hand Lapping a barrel (Read 1457 times)

bubbadoyle · « **on:** May 02, 2006, 05:00:19 PM »

I have a Winchester model 70 rebarreled to 257 Weatherby with an Adams and Bennet barrel. It shoots about 1" to 1.25" five shot groups at 100 yards. My problem is that the it copper fouls terribly. I do not want to firelap the barrel. Is the Wheeler engineering lapping compound that you can buy from midway the right compund to use for hand lapping. I see that it come in a kit for making fire lapping bullets but that the lapping compounds can be purchased seperately from the kit. Is this stuff just for firelapping. Any help is greatly appreciated. Thanks.

lefty o · « **Reply #1 on:** May 02, 2006, 05:57:41 PM »

my own opinion is, you are not going to do your barrel any good by trying hand lap it. either fire lap it, or buy a better quality barrel.

gunnut69 · « **Reply #2 on:** May 02, 2006, 06:29:15 PM »

Lapping compounds are available from Brownells. I would start with about a 600 grit if the bore's really rough. Go to the 800 pretty quick. The petroleum based mixtures provide lubrication as they cut. Ssilcon carbide cuts fastest and longest but will embed. Not a problem for hand lapping. Aluminum oxide won't embed but cuts slower and the longer it's used the finer the chrystals become.. for hand lapping the silicon carbide is my choice and I usually start with 800 grit. If a real finish is desired and it is since we're going to all this trouble the 1200 is used for a final polish. Usually 800 is sufficient but the 1200 can make it really shine.

longgun · « **Reply #3 on:** May 02, 2006, 07:28:44 PM »

Bubba, I think that you will find that most out of the box barrels copper foul pretty bad. Even barrels from Douglas and the like. Unless you pay more money you will likely find they all copper foul. But most will smooth out internally as you shoot them more. But you must clean the copper out after each trip to the range. I shoot silhouette with my rifles and I have to clean after about every 50 shots. But you will have to clean more often untill you get the barrel broken in. I use Sweets 7.62 to remove copper, but there are some good foam copper removers on the market.

About a year and half ago, I made a post here about hand lappeng the barrel, this is the way I do it if you can do a search for that post. It was fairly well detailed. I used the Wheeler kit but have some finer grit powders to finish off with. I have the same dislike for fire lapping that you do. If I were you and the barrel is already installed, I would just shoot it and see if the copper fouling doesn't get better. Don

gunnut69 · « **Reply #4 on:** May 03, 2006, 10:51:49 AM »

Longgun is right about the money. Hand lapping is a labor intensice project if done right and that costs lots of money.. He is also correct in that most barrels will wear in so to speak.. Not all but most. The key is keeping the jacket fouling out of the bore.. Remember the best way to lap is with a cast in the bore lead lap. It's the only way to maintain the uniformity of the bare..

bubbadoyle · « **Reply #5 on:** May 03, 2006, 04:28:23 PM »

I am all set up to cast my own bullets so a cast slug in the bore is not a problem and I am not afraid to put some time into if it will help as I already spend a great deal of time removing the copper fouling. I just need to know what lapping compound to purchase and where I can get it from. All help is greatly appreciated. Thanks.

Mikey · « **Reply #6 on:** May 04, 2006, 01:15:16 AM »

The firelapping kits and procedures I have used use Clover Compound to lap the bore. HTH. Mikey.

gunnut69 · « **Reply #7 on:** May 04, 2006, 07:14:21 AM »

I don't know what grit the Clover compounds are but Brownells sells compounds in a water soluable and a petroleum based material in the 600-1200 grit range. Anything coarser would only be for really damaged bores. You're just looking to polish the bore thus my 800-1200 grit suggestion.. Brownells has an online sight and will sell to anyone..

bubbadoyle · « **Reply #8 on:** May 04, 2006, 06:33:07 PM »

I looked at brownells and found the silicone carbide compounds. I see 600 grit , 800 grit, and 5 microns. Is the 5 microns the 1200 grit you are referring to.

gunnut69 · « **Reply #9 on:** May 04, 2006, 08:02:28 PM »

My stuffs pretty old and I'm unsure of the actual size although it's marked 600/800/1200. The 5 Micron size is very fine indeed.. I haven't lapped a barrel in some time but since your greatest concern was just metal fouling, I'd start with the finest and see if that won't solve your problems. Remember to keep the grit away from the rod as much as possible and use a rod guide for certain. Wipe the rod at each stroke. Slow and steady is the best pace.. Also the silicon carbide grains will embed if metals differ in hardness so don't reuse the guide for something else.. Never remove the lap from the bore completely as it will be the devil trying to get it back in perfectly realigned. I segregate the lead used for this. I know the grit will almost certainly be rid of the grit when fluxed in the melt but just can't reuse it. I believe I even had seperate lead supplies for each grit.. Been awhile though.. Be sure and use plenty of lubricant and take long even strokes. If a tight spot is felt it can be given sprcial attention. Good luck!!