Barrel Underlug question: holes or slots

[oldracer]

I am assembling a Lehigh muzzleloader kit from the fine folks at Muzzleloader Builders Supply. I am progressing right along and have drilled the holes for the rod thimbles and also the barrel underlugs. I noted in one post that the lugs had short slots in them that should allow the barrel to move slightly with recoil. I am thinking that this is pretty important and if I just use the holes I have drilled so far them the wood will very shortly rip around the pins? Any advice or instructions are greatly appreciated.

[aflo]

Isn't that for expansion and contraction of the wood stock, which is different from the barrel? The holes in the stock would not be slots.

[smallpatch]

Some slot the Ulugs for expansion and contraction, NOT for recoil. Different materials (wood and steel) expand and contract at different rates. Under extremes, it is possible for the pins to actually bend and potentially split out the wood, say nothing about trying to get them out. (That's most likely how the wood would be damaged)

[The other DWS]

I have heard that theory too.  Has anyone seen an original in which the pinholes in the lugs were deliberately made into slots?  Has anyone seen a rifle in which the wood shrinkage has caused splits along the pin line?

   My opinion here:  We've all seen old guns with wood/metal gaps that seem to be the result of shrinkage over time.  Likewise we have also seen finely crafted arms of equal age or older that is still as tight as if it was glass bedded.  maybe better guns got better care,  Maybe some old guns got stored for years in hot baking attics.  who knows.   I'd guess that any gun that shows shrinkage gaps may have been made with wood that had not been completely or well enough dried to start with and than stored or forgotten in adverse conditions.

In the absence of any documentation of barrel pin splits due to wood expansion or contraction, in well cured wood,  I suspect is is a well crafted solution to a non-existant problem (to missapply and paraphrase the late Jeff Cooper)

[mjm46@bellsouth.net]

I always slot my barrel lugs slightly. The way I see it wood is very dimensionally stable with the grain, but unstable across the grain. The barrel is going to expand lengthwise when it gets hot and will shrink a little lengthwise when it gets cold. A simplified explanation.  It's not the stock changing dimension so much as the barrel changing dimension. The slotted barrel lugs allow the barrel to move lengthwise in the stock without splitting out the stock at the barrel pins, or bending the pins. The pins are there to hold the wood to the barrel the stock dosn't support the barrel the barrel supports the stock. Somethimes I think the thin wood of the forestock can barely support it's own weight.

[rsells]

I leave a round hole through the back lug closest to the breech of the barrel for the pin to insure that the barrel stays seated tight against the wood at the breech, and slot or elongate the remainder of under lugs so that the barrel and wood can expand at their own rates without binding. 
                                                              Roger Sells

[BJH]

Allways slot the lugs. Especially when the stock is fancy(curly) wood. A really curley piece of wood will stretch a apreciable amount with humidity changes. A plain straight grained piece of wood not so much. I usually drill a hole on each side of the pin hole in the lug. Then connect the holes with a jewler's saw and clean up the resulting slot. Including the rearmost lug. Why? The forces of ramming the ball down the barrel in most cases is more than the recoil of the shot, so the barrel is allways at the rear of the mortice any how.  BJH

[B Shipman]

The guys from Williamsburg once told me they built one of their completely handmade rifles, the lugs were slotted, the customer displayed the rifle over a hot air duct, and the forestock shrank and pulled apart into two pieces.
Barrels do not shrink to any measureable extent. Wood changes, sometimes substantially, and will, no matter how seasoned the wood is.
1. ALL lugs should be slotted. Pins or wedges should not keep the barrel from moving front to back, the tang bolt does that. Otherwise you just create stresses that may crack the stock and some think, affects acuarcy. Snug at the breech front to back. Down on the stock top to bottom.
2. The forestock has nothing to do with strength. Take it away and you have a halfstock. It is a veneer. The strength is in the barrel in which it sits. Thick forestocks are not stronger, just clunky. Weight where you least want it.

[Don Getz]

At one time I had a great Isaac Haines rifle built by Mike Gahagan.   The nose cap was about 1/16" from the muzzle of the barrel.   Almost every time I took this gun to Friendship, which is usually hot and humid, the stock would "grow" to the
point of where it was almost a 1/16" beyond the muzzle............Don

[Dphariss]

I am assembling a Lehigh muzzleloader kit from the fine folks at Muzzleloader Builders Supply. I am progressing right along and have drilled the holes for the rod thimbles and also the barrel underlugs. I noted in one post that the lugs had short slots in them that should allow the barrel to move slightly with recoil. I am thinking that this is pretty important and if I just use the holes I have drilled so far them the wood will very shortly rip around the pins? Any advice or instructions are greatly appreciated.

I like staked in under lugs.
However..
Its possible to make dimples in the bore even with fairly heavy barrel walls. Can't be seen but can be felt.
Dovetails are good, HOWEVER, care must be take to not make them too deep or long. These can also produce loose spots that can be felt with a tight patch or short lead slug. Too deep and too long can and has caused barrel failure to greater or lesser severity at the bottom of the dovetail.
I make stake ins from piano wire and this eliminates the slotting problem if made large enough to allow tolerance for the key. I tend to leave some room for movement in the dovetail type.

Dan

[oldracer]

Thanks everyone for the replies. To hold the tang down and back I have the cross bolt and also the tang bolt. The cross bolt goes right through the middle of the back of the tang as it is stepped. The tang bolt goes into the front of the trigger guard and is pulled pretty tight. I talked to a local rifle builder and master gunsmith named Doug Knoel last night and he said the muzzleloaders he had built all had a hole and no slot in the underlugs. I can see where wood shrinkage might cause cracking issues as noted by everyone. At present I plan to use the holes and watch the holes for any signs of cracks and/or movement after it is finished. I do live in an area (San Diego) where humidity and temps are in a more narrow range than many parts of the country so we'll have to see.

On the CastsBoolits website I have been posting several entries on the construction so far. The forum is at: http://castboolits.gunloads.com/forumdisplay.php?f=16 if you wish to see how I am doing.

[bluenoser]

If I understand correctly, you are referring to the lock bolt as the cross bolt and saying it goes through the breechplug with no clearance.

Personally, I would not do that.  If the breech end of the barrel is not perfectly bedded, or there is any shrinkage or compaction of wood in that area, recoil can be transferred directly to the lock bolt.  The bolt will, in turn, act as a wedge in the wood and could split it.  There is not much wood in that area.  I would make sure there is good clearance between the bolt and the breechplug.  I would also slot the hole in the breech plug toward the rear.

Laurie

[oldracer]

Good point about the lock bolt and I had thought of that and there is a slight amount of clearance in the bolt/hole fit. I also used some epoxy where the breech seats into the stock after covering the breech plug with a layer of saran wrap. I used a very thin coat of the slow hardening mix and brushed on a light coat and then pulled the barrel in tight both axially and radially. I wrapped the barrel/stock with some strips of rubber and then stood the gun up and placed a 20# sledge on top of the barrel to press down.

Yes, yes, yes I know that is NOT they way the old guys did it but as noted that area is very thin and even with the Tiger Maple which is hard, I wanted to make it strong. The old guy that I have been using as my gunsmithing mentor said he had done several this way and they seemed fine after 20 years. If the gun even lasts that long I'll be really happy and I'll be gone by then so it will be my youngest daughter's worry!

[Jim Kibler]

Epoxy is not needed.  Slot the underlugs.  Provide clearance in the breech plug for the rear lock bolt to pass through. 

[smallpatch]

If you put the rear lock bolt through the breech block with NO clearance, you run the risk of splitting the wood behind the lock.  If barrel is not tight against the rear of the inlet, every time you shoot that thing, it will slam the lock rearward.  Don't ask how I know.  The wood of the lock panel, behind the rear point of the lock, is quite thin, and that impact can certainly split it out! No recoil should be felt in that area.  Relieve that hole through the breech block, so the rear of the barrel inlet takes the impact.

[Don Getz]

Good advise Dane.   I always make sure that the bolt going thru the bolster of the breechplug is larger than the bolt
itself, should be some slop in there.    A tight bolt in this area can affect how well the gun shoots.........Don

[Pete G.]

A tight fit of the rear lock bolt doesn't risk a crack, it ensures it. Notice how many old rifles have a crack from the lock bolt aft. In my admittedly limited inspection of old rifles (about a half dozen) they ALL had slotted underlugs. There is no need to relearn old lessons about problems that have already been solved. You will discover plenty of new problems in need of solution with every new build.

[B Shipman]

Well said.

[cmac]

There are pictures of an original here (  http://cmacsflints.blogspot.com  )that had slotted lugs with pins

[Ryan McNabb]

I wonder if the ones with the nosecap screwed to the barrel had slotted lugs?     You can go either way - slotted or not.  I've not seen it make a difference.  If you're really concerned about accuracy, you'll use hickory for the draw pins.  Hickory "draws" will keep her from "playin' her balls." 

[sscrm13]

Hey Ryan, longtime no see or hear, I hope all is well.  Actually in regards to nosecaps being screwed to the barrel, the only one i have examined in detail was the #42 rifle, which had the wood slotted underneath the nosecap.  Whether it was for seasonal movement or just made that way so the nose cap would slide off nobody can be certain but it would aid in preventing the wood from splitting.  that said the underlugs are not slotted, they have perfectly round holes.  The Early Schroyer is the same way.