safe tolerences for barrels

[David R. Pennington]

What I have is a 13/16"- .45 cal. 48" barrel from 1973. Never bored for touch hole but someone installed lugs. Eight lands and grooves with .020 deep grooves. Groove to outside flat wall thickness measures .182. Lug mortise is .050 which leaves .132. wall thickness between groove and outside flat. Is this a safe tolerance?

[galamb]

My math is coming out a little different.

13/16" = .8125" outside flat to opposite outside flat

.450 (caliber) with .020" groves (per side - so .040" total - unless you actually meant .010" grooves for a total of .020") means a (max) .490" "hole".

.8125 - .490 = .3225 (divided by 2) = .16125" wall thickness at the extreme of the rifling to the outside flat.

A .050" mortise in that would leave (.16125 - .050) .11125" of wall thickness (adjacent to the groves).

Anyhow, most sources consider a minimum of .050" of wall thickness "safe", my personal margin is .080" - less than that and I solder on lugs instead of cutting in/or staples.

You have lots...

[Acer Saccharum]

But you don't have lots of wall thickness for a drum.....

[bgf]

Somewhere, maybe the Rice site, I saw 1/10" thickness regarded as safe. That is the only number I've ever seen from a source that had any credibility.  I think it has been discussed before.

[Mark Elliott]

The only number I have ever gotten from either Getz or Rice is a max .050" depth for dovetails (sights or tenons).   Since the only barrels I have used in years are Getz or Rice,  I only worry about the dovetails.   I generally shoot for and hit .040" dovetails.   

[B.Habermehl]

Your barrel is safe. However I would not use a drum and nipple set up for percussion. Not enough wall thickness for threads that will be subject to shock. It'll due just fine for a flint gun.BJH

[David R. Pennington]

 My math was based on the actual measurements I made with dial calipers. It will be a flint lock rifle of course. Now I need to make a new breech plug. The one in it is questionable. It looks like 9/16-12 threads but I need to find my pitch gauge and be sure. Some of the threads on the plug have chipped off and there is a strange little void like a deep center drill hole in the face that would collect fouling. I went through all my taps and dies and don't have one that matches. The threads in the barrel look ok and I don't really want to cut it off if I don't have to. I don't think any one sells plugs with that coarse thread these days.

[Bob Roller]

My math is coming out a little different.

13/16" = .8125" outside flat to opposite outside flat

.450 (caliber) with .020" groves (per side - so .040" total - unless you actually meant .010" grooves for a total of .020") means a (max) .490" "hole".

.8125 - .490 = .3225 (divided by 2) = .16125" wall thickness at the extreme of the rifling to the outside flat.

A .050" mortise in that would leave (.16125 - .050) .11125" of wall thickness (adjacent to the groves).

Anyhow, most sources consider a minimum of .050" of wall thickness "safe", my personal margin is .080" - less than that and I solder on lugs instead of cutting in/or staples.

You have lots...

  .020 grooves?Sounds like splines to me and what would the patching be,
an old overcoat? Has anyone seen any barrels from the flintlocks only era
that were this thin in a RIFLE?

Bob Roller

[Bob Roller]

What I have is a 13/16"- .45 cal. 48" barrel from 1973. Never bored for touch hole but someone installed lugs. Eight lands and grooves with .020 deep grooves. Groove to outside flat wall thickness measures .182. Lug mortise is .050 which leaves .132. wall thickness between groove and outside flat. Is this a safe tolerance?

Who made that barrel?In 1965,Leonard Meadows made a custom Tn long rifle for me
from a Bill Large barrel that matched those dimensions.It was a flintlock full stock made
from walnut with iron trim from a wrecked antique rifle.Bill was using 1144"Stressproof"
in those days and didn't start using leaded steels until about 1975.The 1144 was what
I made and still make tumblers from and used a lot of random short pieces from Bill that
were to short to make barrels from.
I can't say the barrel you have is safe and neither can anyone else if it's not certified for
gun barrels but I would NEVER install a drum and nipple in it regardless of any opinions
to the contrary.

Bob Roller

[David R. Pennington]

Bob, Boyd Henry in Buchannon, WV made the barrel and signed it on bottom flat with  what looks like an electric engraver and dated it 1973. I heard that Mr. Henry's rifling machine was the one that Jim McCartney used. I also heard Mr. Henry was a descendant of the famous Henry family of gun makers.

[Bob Roller]

Bob, Boyd Henry in Buchannon, WV made the barrel and signed it on bottom flat with  what looks like an electric engraver and dated it 1973. I heard that Mr. Henry's rifling machine was the one that Jim McCartney used. I also heard Mr. Henry was a descendant of the famous Henry family of gun makers.

That sounds vaguely familiar.Leonard Meadows lived in Shady Springs WV just out of Beckley
and I still have the letter he sent me when the rifle was ready.It is three pages long and he said
his dog was pregnant and his truck had a broken ring and lastly,"Yer riflegun is done".
I made a number of locks for him and some of the flintlocks had a dagger tail welded to the
plate to give a different look altogether.

Bob Roller

Bob Roller