Hand Lapping a barrel

[Larry in wyoming]

I read several old posts and I still haven't made up my mind about it.
I ran a bore scope down the barrel of my savage 308 and found lots of tool marks. I wish I hadn't done that. LOL
Now, this rifle shoots pretty good and it doesn't accumulate copper any worse than my other rifles. But I KNOW that bore is rough and I mostly know how to fix it. Also, I have most everything I need to do the job. I don't want to do a firelapping job on it. I've read too many horror stories about lengthened throats.
Any tips on pouring the lap? What kind of cleaning rod? What kind and size jag?
TIA

 

[Tinman357]

I'd like to learn the in's n out's of this as well. While I understand the theory of it as well as the mechanisms, I've done enough to know that the devil is in the details.

 

[Slamfire]

I read several old posts and I still haven't made up my mind about it.
I ran a bore scope down the barrel of my savage 308 and found lots of tool marks. I wish I hadn't done that. LOL
Now, this rifle shoots pretty good and it doesn't accumulate copper any worse than my other rifles. But I KNOW that bore is rough and I mostly know how to fix it. Also, I have most everything I need to do the job. I don't want to do a firelapping job on it. I've read too many horror stories about lengthened throats.
Any tips on pouring the lap? What kind of cleaning rod? What kind and size jag?
TIA

Stop looking and just shoot. I promise, were you the size of a water molecule, a mirror finish bore would look like the Grand Canyon.

Sometimes, and I mean in this case, it is better not to have one of those bore scopes. It just creates uncertainty and doubt in your mind. And, why do you assume that a tool mark free bore will necessarily shoot better than one without? Is this a shiney thing bias? A monkey brain thing? Does shiney brass shoots better than grungy brass? (some believe it, and huge numbers of people won't shoot any but shiney brass) Where can you find a tool mark free rifle barrel? I heard of some EDM 1911 barrels, and per the article they were in, they were not superior in accuracy to any of the broach or button cut barrels. No doubt they were shinier. Can't say I have looked down the tube of a hammer forged barrel.

I am going to claim there is nothing you can do with a cleaning rod and a lap that will improve the accuracy of your barrel. And you might make things worse.

 

[Larry in wyoming]

That's the thing slamfire, I don't actually care of it shoots better. Just so long as it doesn't shoot worse! Like I said and you also said, I wish I hadn't looked. But now I can't un see those tool marks. I'm going to try and ignore them but if I cant.....

 

[Blue68f100]

The only time I do it is when I have a barrel that is hard to clean due to copper fouling. Normally on a rifle its the areas where the chamber was cut transiting into the rifleing. Most of the higher end match barrels (rifles) have already been hand lapped.

 

[starnbar]

I read several old posts and I still haven't made up my mind about it.
I ran a bore scope down the barrel of my savage 308 and found lots of tool marks. I wish I hadn't done that. LOL
Now, this rifle shoots pretty good and it doesn't accumulate copper any worse than my other rifles. But I KNOW that bore is rough and I mostly know how to fix it. Also, I have most everything I need to do the job. I don't want to do a firelapping job on it. I've read too many horror stories about lengthened throats.
Any tips on pouring the lap? What kind of cleaning rod? What kind and size jag?
TIA

If I was you I would leave it alone if it shoots ok then it is ok remember what you are doing is removing metal from the bore the only times I do that is when I am building racing engines and they only have to last for around 600 miles or 28 hours.

 

[JFrank]

That's the thing slamfire, I don't actually care of it shoots better. Just so long as it doesn't shoot worse! Like I said and you also said, I wish I hadn't looked. But now I can't un see those tool marks. I'm going to try and ignore them but if I cant.....

Carry the tool marks as a badge of honor’ those barrels are already lapped, afaik

 

[Jim Watson]

It's a Savage. Easy to replace the barrel if lapping does more harm than good.
I have WATCHED barrels being lapped, it is not a complicated job. It didn't do mine any good, though.

 

[JFrank]

The only time I do it is when I have a barrel that is hard to clean due to copper fouling. Normally on a rifle its the areas where the chamber was cut transiting into the rifleing. Most of the higher end match barrels (rifles) have already been hand lapped.

My old buddy Stan Taylor of Douglas barrels told me that his pulled button rifling was the only ones that did not require lapping, push button and cut riflings must be lapped. Hammer forged I do not know about.

 

[Jerry M]

If the rifle is shooting well,, why not just keep shooting it? You'll eventually smooth out the machine marks.

 

[earlthegoat2]

The answer lies in how it shoots right now.

 

[Clemson]

If you can find a copy of Roy Dunlap's book Gunsmithing, He gives about three pages of lapping procedure. It starts on page 217 in my copy (June 1979).

 

[Larry in wyoming]

I took some pictures of the bore just for grins. This is after about 50 rds. I have brushed it and used some gunslick foam and some butches bore shine on it.

 

[Douglas Lee]

Looks like my Ruger M77 VT barrel.

 

[PapaG]

I would start with JB paste on a tightly patched jag and give it fifty full strokes without leaving the muzzle. Rinse, clean, repeat, lol. I've brought back several pretty bad black powder and one smoke damaged 17 HMR this way. I did lead lap my late Uncles Krag, ruined with sixty years of blank funeral slutes. I used 1/4" drill rod, grooved for an inch at the end. Oakum wrapped below the grooves. Barrel with rod in place held vertically, carefully warm barrel with propane torch, lead already melted. Pour. Since this was a last ditch salvage attempt I simply bought some 4F valve grinding compound. Mark the lap before you push it out, then roll it on a plate with the compound on it. Reinstall in barrel and make careful full length strokes. Krag will now shoot 3-4 MOA with no key holes using issue sights. Bore still looks like a mile of sewer pipe but the defects are smoother. Yours probably doesn't need any of this.