[Mughi-14]

Hey everyone,

I've heard a lot about firelapping a barrel as an expedient way of improving accuracy, but I would like to try the traditional hand lapping method on a rifle as well. I haven't found much on it, though (traditional lapping); I have plenty of info on firelapping, including some throat-erosion info that makes me leery of it. The Tubb kit seems safer (pre-embedded grits on 80gr BTs and a set of instructions) than just plastering grit on some lead slugs and hoping (my confidence in my own judgment is underwhelming).

Can anyone direct me to some info on traditional lapping (pushing the lead slug through the barrel by hand)? Any books that I should look at? I remember Z-Man mentioning something about this method also.

I know that I could lap it with the materials I have (either firelapping or traditional), but when to stop is the question.

Thanks,

Mughi-14

 

[cajungeo]

Hey mughi. Here is a link on barrel lapping. The only parts I'm not shure I agree with is: (1) the grits. I used 220, 320, and 600 grit when I firelapped mine. I stretched the case neck using a .243 neck expander so when seating the bullets the grit would not scrap off. The part of the bullet in the case is what laps. Putting it on the tip does little good. (2) They say to remelt the lead, that grit is then imbedded. I would make a new slug for each grit, or use enough flux so you can spoon off the grit from the molten lead.

Either way works fine. If you pull a Lead .22 LR bullet, use it for a slug. Push it thru with a flat jag. You will feel the tight spots. Put a piece of tape on the outside of the barrel to mark the spots. The other thing is you may have to recrown, if you wear it down.

Just a note if you decide to load some lapping bullets, only use lead bullets, no jacket. Only enough powder to shoot the bullet. I used 3 grns, of H110 at the time it was all I had. Use a fast powder. Stretch the neck of the case to .243". Reload finest grit first, coursest grit last. I fired 10 rds of 220 grit, 10 rds of 320, then 10 rds of 600 grit, cleaning between shots, and especially between grit changes. It removed the tight spots, and smoothed the bore. Accuracy improved by an average of 1/4" at 100 yds, and need less cleaning. It worked for me.
http://t6aluminum.tripod.com/Barrel_Lapping.htm#Top

 

[Mughi-14]

Thanks Cajungeo.

I appreciate it. Now to melt some lead...

Mughi-14

 

[mtnwatcher]

so Cajungeo, if i push a 22lr slug thru my barrel and there are tight spots, is that an indication i should firelap?

what are some other methods for determining if one needs to firelap?

 

[cajungeo]

There are 2 tight spots you will always have. The crown/muzzle (thats a good thing for accuracy) the other is the gas block. As stated previously, I reduced it, but with the gas block on it compresses the barrel, with out the gas block, that tight spot is gone. If you feel others, the firelaping will get rid or reduce them. Even if you don't have any, the rough ruger barrel has a lot of machine marks.
Firelaping polishes these machine marks so there is less friction, better accuracy, less fouling. I had a couple other tight spots, and they were gone afterwards.

If you had a bore scope you could see the machining marks. I don't have a bore scope, but I could feel the cleaning patches against the lands, it felt rough to me.

I researched everything pro, and con, on laping, and firelaping. I did it , as I was trying to get my mini at or very near 1 moa, for coyote hunting at up to 300 yds, and at low cost. So procedded to tune my mini. Out of box winchester 45 grn varmint shot 4 1/2", BW muzzle brake, 2 1/4" groups, bedding, and trigger job 1 3/4" groups (both got rid of flyers), firelaping barrel 1 1/2" groups, Seirra 62 grn sp. reloads 1.15" groups.

I used a benchrest at 100 yds. 5 shot groups for 5 to 10 groups, then averaged, best to worst. Measured center to center.

If I had an older rifle, or it was already shooting 1 moa or better, or only used the rifle for plinking or close range self defense, I'd probably not bother with it. On the other hand being interested in the max accuracy for long range shooting, and not a lot of money, I laped it. It works for me.

 

[Abendicum]

"HAND LAPPING" is not recomended because the barrels are mushroomed out a few thousands at both ends by the hand lapping process... Barrels are then trimmed back a few inches at both ends to remove the "mushroom affect" before chambering and muzzle crowning.

Hand lapping opens up the ends of the barrels when inserted and reinserted. It is also done by skilled craftsmen who have been doing it a while...

In a chambered rifle the throat would see excessive erosion... as would the muzzle... However if one were planning on shortening the barrel then damage to the muzzle would be of no concern... as it would be cut off and recrowned...

Fire Lapping has none of the detrimits of hand lapping with good
results on mini's or any production rifle... (It is also done with finer "grits) Pre-coated bullets in a patented process are available from NECO which are already coated with the proper grits... Contrary to what has been said above they are copper jacketed coated bullets in 200, 400, 800 and 1200 grit bullets...

Powder charges are calculated with fast burning powder (not reduced rifle powder) at speeds between 1500 fps and 2000 fps. There is an advantage in using normal copper jacketed bullets for coating... They best recreate the expansion and contact on the rifleing that a normal jacketed bullet does... It is slowed down to maximize its contact "time" with the lands to best remove high spots with course grits and smooth the bore with finer grits...

I created the Russian 7.62x39mm "caliber" NECO bullet set in .311 diameter and have sold them for more than a year... I have seen seen remarkable improvements (as have many others) with my SKS... 1-5/16" 3 shot groups @ 100 yards.
AB