hand lapping a barrel

[schughes]

I have become interested in this topic as a means of polishing a factory Savage 6mmBR barrel so that it doesn't foul as much. I have never done it but then I had never Devcon bedded stocks until I did the first time. I am a firm believer that I can do anything that I need to do as long as I don't mind paying twice for it!! LOL

I have done a lot of reading and my question seems simple. So I pour a lead lap by inserting an old cleaning rod or something of that nature then coat the lap with various grits of media until it polishes out somewhere around 1200 grit. In doing this I "feel" for tight spots and continue to lap until I there seems to be no obstruction. So what wore down? Did the stainless steel barrel wear down to smoothness or did the lead lap simply wear down? It seems that the lap is much softer than the barrel. What am I missing?

 

[NateHaler]

I say look before you leap when it comes to using abrasives in your barrel. I suggest using JB bore compound on an oversized bore mop (e.g. .338-.375 bore mop in a .308 bore). Twenty strokes, then remove and clean the bore thoroughly. Replace the bore mop with a new one. Repeat. Three more rounds of that, and you'll have 100 lapped strokes, right?

Toss the bore mops into a cleaning solution. Clean the bore thoroughly, and go shoot. Check for copper fouling using the Q-tip in the muzzle method. If it's fouled there, it's fouled.

Even so, regarding fouling, does it affect your accuracy or just your peace of mind? (Which can certainly affect your results!)

 

[GerryM]

BORE LAPPING'?
You can clean it up a tad but lapping is another story.
casting a lap is one thing but doing it without runing your barrel is another. To do the job the way it's done in a barrel makers shop requires not only skill lapping but also the proper equipment.
Its usually done in a vice before the barrel is chambered.
An air gauge is used to check dimensions as it's lapped.
The lap is cast several times also. The barrel is lapped at both ends .
After lapping a notch is cut about 1 inch from the end.
The reason for this is the muzzel may have a taper or bell on the end.
The last inch is cut off.
What ever you do be carefull . I would hate to see you loose a good barrel.
I would just clean it up a tad with a lap and some jb, being careful not to over do it. If the barrel has reamer marks in it forget it. thats about as good as it will ever be,
I hope this helps you and good luck

 

[schughes]

Thanks. I think that I will try the sweat, mop and polish route first. My concern is that an inordinate amount of fouling (carbon and copper) means a rough internal surface that may be deliterious to accuracy. It's a new barrel with only 60 or so rounds down it so it is certainly not "ripe" yet. It groups around .5+ MOA but I am frankly used to better than that from a factory Savage LPV in 22-250. I have shot in the .1s with it but after a couple hundred rounds. That one is regularly in the 2s and low 3s with a half blind old man behind the glass. I will give that a try before I get into the more serious stuff.

 

[Dave2]

I know that you specifically asked about hand lapping, but have you considered fire lapping with the Final Finish (I think) bullets from David Tubb?

 

[GerryM]

What ever you do . One thing has to be done.
Flush the bore with carb cleaner or some other type bore cleaner.
Clean the bore with a good bronze brush and you favorite solvet . Patch out. when your done.
Make sure you have all of that compound out of the bore before shooting. You will be amazed at what will come out.
At the end of the day i clean with IOSSO and oil,
I flush and brush after with more solvent and patches.
It's the best way to keep it clean.

 

[butchlambert]

You may keep in mind that the custom barrel guys lap at 320grit. You do what you have in mind and it will really copper foul.
Butch

 

[Illinois_shooter]

Butch is right on, The pored lead slug is good, I use 400 grit, Bore scope it to tell when you have accomplshed what you want, Then I flush with Carb cleaner, Then break the barrel in with 1 shot clean for 5 shots then 2 shots for 5 times, then you should be reeady. Just my .02

 

[PFAK]

I would only consider firelapping the barrel since you can't lap the last inch of so of the barrel without the lap coming out of the bore. I guess if you cut that section off you might be ok,
just like you do when you chamber and crown a new barrel.

 

[blawton]

Yes whenever you lap a chambered crowned barrel you better be ready to cut some of the front and may even need to move the chamber some as well. I suggest using some 400 grit on a patch on a brush thats a caliber small. Just work the throat for the first few inches of it about 20 storkes then reapeat with the next patch containing jb or issoi. After that i patch it out with some kroil and the coppering usually decreases by about at least half or better just about every time. Good luck!

 

[Matt Pitchon]

I fire lapped a Savage 22lr using the David Tubb stuff. The goal was to improve accuracy. The groups went from about 1" at 50yds to 1/2", a considerable improvment. The barrel was new when I started. I have no idea if will reduce copper fouling, but in my gun, the accuracy improvment was remarkable. I was very skeptical about this process, but it worked. I have heard about situations where is hasn't helped, but none when it hurt. I think fire lapping is much safer than hand lapping for all the reasons stated in prior posts.

 

[Kenny474]

I would also recommend Tubb's final finish. He also makes the TMS, which is the throat maintenance system. I would look into that before I started trying to hand lap myself.

 

[DickE]

Listen to Butch, if it's too smooth....problems. If it's too rough.... problems.

 

[jim_k]

Tubb's bullets are the way to go for the vast majority of people. Then routine TMS use. The only people who don't need that are the ones who can diamond-lap their own barrels. Going out on a limb here, but all barrels have about the same potential for accuracy, once they've been properly bedded and diamond-lapped (rare exceptions excepted). Chrome moly barrels have been the equal of cut stainless barrels. Since bluing is not free for me (I can't do it), I mostly shoot factory or stainless barrels. My 1976 Winchester Ultramatch has a factory hammer-forged Ultramatch barrel, and it has been diamond-lapped. Most recent 5-shot group was 0.35". I'd recommend a cheap experiment: look for a gunsmith with some factory takeoff barrels, and get one put on a rifle that already shoots. See how large the groups are, then do the Tubb fire-lapping. See what size the groups are. Share the info. David Tubb can pay me a portion of his increased profits after that.

 

[butchlambert]

A 9 year old thread.

 

[BoydAllen]

Yes, I know that it is old. One more thing( OK I lied, several), none of the posters seems to have a clue about what is actually involved in lead lapping a barrel. They don't understand that it is often not a matter of just casting one lap. They talk about polishing as if it was desirable for a CF barrel, and no one has said anything about slugging up the lap when needed, or critical measurements that need to be made before attempting lapping. For all of you guys, it is your hobby, do whatever you like, but my advice is that you not work with a barrel that has much value, and most of you will end up explaining why what you end up with is marginally better.

 

[Dusty Stevens]

Be sure to use your air gage to keep up with your lapping progress.

 

[BoydAllen]

I have become interested in this topic as a means of polishing a factory Savage 6mmBR barrel so that it doesn't foul as much. I have never done it but then I had never Devcon bedded stocks until I did the first time. I am a firm believer that I can do anything that I need to do as long as I don't mind paying twice for it!! LOL

I have done a lot of reading and my question seems simple. So I pour a lead lap by inserting an old cleaning rod or something of that nature then coat the lap with various grits of media until it polishes out somewhere around 1200 grit. In doing this I "feel" for tight spots and continue to lap until I there seems to be no obstruction. So what wore down? Did the stainless steel barrel wear down to smoothness or did the lead lap simply wear down? It seems that the lap is much softer than the barrel. What am I missing?

If you polish with 1200 grit, your barrel will copper foul forever. There are good reasons that barrel manufacturers finish with coarse grit. I used to think that 320 was the number, what I have learned is that coarser is required. Barrel makers tend to hold onto the specifics of their lapping. My friend ruined the first centerfire barrel that he tried lapping. That is why I said that you should not start on an important barrel. You will not get do it by the numbers instructions on how to lap on an internet forum, because few if any who post have much if any experience actually doing it. I know a lot of what my friend does, but he has bought that knowledge with sweat and money, and it is not mine to give away. This is a lot harder than bedding, or ring lapping, or any minor gunsmithing that I can think of. Lots of people will tell you how to blueprint an action, or thread and chamber a barrel. This is different. It will test your problem solving ability. If you manage it, you will have something to be proud of.

 

[Brians356]

One more thing( OK I lied, several) ...

You only "misspoke".
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[Brians356]

If you polish with 1200 grit, your barrel will copper foul forever. There are good reasons that barrel manufacturers finish with coarse grit. I used to think that 320 was the number, what I have learned is that coarser is required.

An analogy comes to mind: When you hone a brake or engine cylinder, you don't polish the bore, you strive to leave a uniform crosshatch pattern. Valid (if loose) comparison?
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