Author Topic: Lapping barrels?  (Read 2977 times)

m1garand_man

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Lapping barrels?
« on: May 04, 2018, 09:21:45 PM »
Is there any point to lap a rifle barrel on a flint lock? I've done it with other rifles I own but am not sure if there would be any benefit to do it to the rice barrel on my flint lock. One thing I read about lapping when it came to early original guns esspecially with hawkers was to not lap the last inch or so before the muzzle so as to be sure that the tightest part of the bore was the muzzle.

Do you think I should even bother? I'm not sure that it will do much for accuracy with my gun.

Offline T*O*F

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Re: Lapping barrels?
« Reply #1 on: May 04, 2018, 11:22:14 PM »
You've shot it enough already that its not required.  After 200 shots or so, you have already removed any sharp edges on the lands.  Some guys do this on new barrels before firing by shooting 10 rounds with the patches loaded with JB paste or Clover valve grinding compound.  Both accomplish the same thing, one just does it sooner.
Dave Kanger

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Offline BOB HILL

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Re: Lapping barrels?
« Reply #2 on: May 05, 2018, 01:12:30 AM »
I’ve never felt that Rice barrels needed any rough edges removed. They are smooth when you get them.
Bob
South Carolina Lowcountry

Online Bob Roller

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Re: Lapping barrels?
« Reply #3 on: May 05, 2018, 01:43:20 AM »
You've shot it enough already that its not required.  After 200 shots or so, you have already removed any sharp edges on the lands.  Some guys do this on new barrels before firing by shooting 10 rounds with the patches loaded with JB paste or Clover valve grinding compound.  Both accomplish the same thing, one just does it sooner.

Be careful with the valve grinding compound, it can ruin the barrel.
Old machinist here,Clyde Gibson always said "Lapping is just covering
up a boo boo.

Bob Roller

Offline D. Taylor Sapergia

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Re: Lapping barrels?
« Reply #4 on: May 05, 2018, 02:09:44 AM »
It can also repair a boo - boo.  My buddy Petyer ruined his Getz A weight .40 cal barrel by using boiling hot water to clean, causing flash rust that over time simply accumulated to the point that the bore was FUBAR.

When he passed away, he left me the rifle, and Daryl and I spent about 8 hours lapping it.  It now loads, shoots and cleans fine, but it is not as good as it was when new.  I'd never lap a new barrel, unless I was trying to introduce a choke.  I have yet to find a modern made barrel that straight from the maker needed choking to improve its shooting.
D. Taylor Sapergia
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Offline T*O*F

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Re: Lapping barrels?
« Reply #5 on: May 05, 2018, 02:20:45 AM »
Quote
Be careful with the valve grinding compound, it can ruin the barrel.
Old machinist here,Clyde Gibson always said "Lapping is just covering
up a boo boo.
When Ernie had Badger Barrels, he hand lapped all his cut rifled, target barrels with valve grinding compound.  Mike Rock did the same.  He showed me how it was done when I visited his barrel making facility.  He has 18 Pratt-Whitney barrel machines.  He has a PhD in metalurgy and his barrels have Olympic medal credentials.  He also makes rifles for select Special Forces units that will shoot sub-MOA groups from an 18 inch barrel.  Old guys don't always know what they are talking about.
Dave Kanger

If religion is opium for the masses, the internet is a crack, pixel-huffing orgy that deafens the brain, numbs the senses and scrambles our peer list to include every anonymous loser, twisted deviant, and freak as well as people we normally wouldn't give the time of day.
-S.M. Tomlinson

Offline T*O*F

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Re: Lapping barrels?
« Reply #6 on: May 05, 2018, 02:22:50 AM »
Quote
I have yet to find a modern made barrel that straight from the maker needed choking to improve its shooting.
The Pedersoli Gibbs rifle comes from the factory with a choked barrel as do several others of theirs.
Dave Kanger

If religion is opium for the masses, the internet is a crack, pixel-huffing orgy that deafens the brain, numbs the senses and scrambles our peer list to include every anonymous loser, twisted deviant, and freak as well as people we normally wouldn't give the time of day.
-S.M. Tomlinson

Offline D. Taylor Sapergia

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Re: Lapping barrels?
« Reply #7 on: May 05, 2018, 08:04:22 AM »
That I did not know Dave.  I DO know that Pedersoli makes good barrels and I have seen several shoot very nicely.  I was primarily making reference to makers like Getz, Rice, Green Mountain, Orion, Colerain, etc....the kinds of barrels we commonly use to make our longrifles.
D. Taylor Sapergia
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Offline P.W.Berkuta

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Re: Lapping barrels?
« Reply #8 on: May 05, 2018, 07:18:11 PM »
One of the issues with lapping a barrel is getting ALL the lapping compound OUT of the barrel when finished lapping ;).
"The person who says it cannot be done should not interrupt the person who is doing it." - Chinese proverb

Offline Daryl

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Re: Lapping barrels?
« Reply #9 on: May 05, 2018, 08:03:36 PM »
I lapped a choke into a Bauska .50 barrel that had 38" twist rifling and .008" deep grooves. That was an accurate barrel and won many turkeys

Against the same guys I shot 3-position with. They used their suppository shooting scoped match rifles.  I had a post front sight and a TC aperture

rear sight.

On a good day, I could shoot 1" to 1 1/2" at 100 yards.  Those turkey shoots were all offhand shoots, something those guys did not practice enough.

Offhand is all we used to shoot with our muzzle loaders - & every weekend.

A choke certainly helps in a shot-gun or bullet shooter. I am not convinced it is necessary or desirable in a round ball gun - yet. I am open to receiving

one for testing, though. ;)
Daryl

"a gun without hammers is like a spaniel without ears" King George V

Offline Scota4570

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Re: Lapping barrels?
« Reply #10 on: May 06, 2018, 06:15:52 PM »
I've lapped several messed up barrels.   I do not lap good barrels.  I start with #120 valve grinding compound.  I put a screw in the lap to expand it.  I work down to #320 grit.  It takes several laps.  I do put a choke.  IF nothing else it makes loading easier. 

The last one was a TC with a damaged land about half way down.  The current owner consistently wins local matches with it.

Offline Dphariss

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Re: Lapping barrels?
« Reply #11 on: May 10, 2018, 04:06:12 PM »
Most "modern" cut rifled barrels are lapped. Krieger laps all their barrels and do a number of other barrel makers. I am pretty sure most iron barrels were lapped back in the day. The reason most modern ML barrels are so smooth is the material they are made from. 4140 for example or even iron is a lot harder to cut smooth. Button rifled barrels can often benefit from lapping since the button does not really "iron out" the reamer marks.
Dan
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Gary W.E.

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Re: Lapping barrels?
« Reply #12 on: May 11, 2018, 04:54:32 AM »
I ordered a new 40 cal Rice barrel and the Rice Rep advised me to have them lead lap the barrel before they ship it to me. I took him up on it and have never shot a better barrel.

m1garand_man

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Re: Lapping barrels?
« Reply #13 on: May 11, 2018, 04:30:11 PM »
Most "modern" cut rifled barrels are lapped. Krieger laps all their barrels and do a number of other barrel makers. I am pretty sure most iron barrels were lapped back in the day. The reason most modern ML barrels are so smooth is the material they are made from. 4140 for example or even iron is a lot harder to cut smooth. Button rifled barrels can often benefit from lapping since the button does not really "iron out" the reamer marks.
Dan

Origional barreles certainly were lapped. Have read about it and they mention it in the 1960s Williamsburg documentary about how long rifles were built. You can watch that documentary on youtube. It's very informative and even enteraining.

Offline Daryl

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Re: Lapping barrels?
« Reply #14 on: May 11, 2018, 06:40:09 PM »
I followed Ned Robert's directions on lapping in a choke with a lead lap - worked really well for me.
Daryl

"a gun without hammers is like a spaniel without ears" King George V

Offline Waksupi

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Re: Lapping barrels?
« Reply #15 on: May 13, 2018, 10:49:13 PM »
I usually lap a bit on general principle when building a gun. Most don't need it. The builders are pretty diligent about putting out good barrels, and it's darned hard to find a bad one from any builder. Shoot them a few hundred times, and they will generally smooth out.
The only gun I ever built that really needed lapping was a Judge Resley barrel that he had made probably 50 years ago. The bore was great, but the grooves were rough as a cob.
I'd put 500 rounds out of it, and it was still cutting patches. I impregnated some patches with valve lapping compound, and fired ten shots with around 10-15 gr, powder. Took care of the problem, and still shoots great today. 
Ric Carter
Somers, Montana