Underlug hole elongation...

[J.D.]

I personally do not elongate my underlug holes, i use spring steel wire that is tempered at 800 degrees. This provides a rebounding to the barrels movement preventing the stock from cracking. When you use mild steel wires like nails or coat hangers the pins bend and yield to the recoil and pressures from the barrel.

The reason for elongating the slots is not to allow for recoil of the barrel. It is to prevent damage to the forestock as the wood expands and contracts with changing ambient moisture. IMHO, the slots in the underlugs should be longer close to the muzzle, because of more potential movement of the forestock farther up the stock, in damp, rainy weather.

 

[James Kibler]

Yes, and a very bad idea not to elongate. Listen to the professionals and experts.

 

[SDSmlf]

I personally do not elongate my underlug holes, i use spring steel wire that is tempered at 800 degrees. This provides a rebounding to the barrels movement preventing the stock from cracking. When you use mild steel wires like nails or coat hangers the pins bend and yield to the recoil and pressures from the barrel.

I have read in Shumway’s books that some old guns he examined with no slots in their tenons had fore-stocks pulled apart by up to an 1/8”. There must have been a lot of recoil and pressures from the barrel back in the day? Or maybe the stock wood expanded and contracted over time?

 

[James Kibler]

Wood movement. Don’t underestimate it

 

[SDSmlf]

Below is a photograph an unfired, CVA factory made gun, with 40 plus years in a humidity controlled environment (Heat/AC plus dehumidifier in the safe). It’s been on my todo list for years to slot the tenons so the stock is free to move over time without opening up seam between the two pieces, but with a gun that’s never been shot it just doesn’t get to the top of the list. Imagine the stress between the pins and the stock if the two piece stock didn’t allow movement?

 

[oldwood]

In the late 1970's , a few folks began to teach a Muzzleloader rifle building class at a local high school. Out of 5 or students , 2 of them clamped and pinned their longrifle barrels solidly to he undersides of the wood stocks. These two students had rifles that wouldn't hold a good group as seen on a shooting range. Elongating the pin holes fixed the accuracy problems. First hand experience convinced me , elongation works. Most "how to build m/l's" manuals have the elongation info in them as well.

 

[FlinterNick]

The reason for elongating the slots is not to allow for recoil of the barrel. It is to prevent damage to the forestock as the wood expands and contracts with changing ambient moisture. IMHO, the slots in the underlugs should be longer close to the muzzle, because of more potential movement of the forestock farther up the stock, in damp, rainy weather.

I’ve never elongated my tenon slots, I’ve never had issues with the forestocks breaking or even chipping. Not saying it shouldn’t be done here, just saying what I’ve done and observed. Most of the time i think forestocks break because the pins are drilled sloppy and the pins themselves are rough with edges and burrs.

I put a lot of attention into the lugs and pins, i debur them, polish them, chamfer etc. I make sure they’re not too tight and not too lose, I counter sink the pin holes slightly, so that the pin chamfer moves in the tenon. It may not be the music wire that I use that is the difference for me, not sure but again, I’ve never broken a forestock around the tenons. I also make sure the areas are lubricated / conditioned with renaissance wax.

I’ve got a fowler in my shop with underlugs that have one and two wholes, the pins themselves are filed thinner in the middle, i don’t know why, they have edges and burrs, and the pins are very messy 3/32 nails, and the forestock is cracked, the lugs are not elongated.

 

[FlinterNick]

In the late 1970's , a few folks began to teach a Muzzleloader rifle building class at a local high school. Out of 5 or students , 2 of them clamped and pinned their longrifle barrels solidly to he undersides of the wood stocks. These two students had rifles that wouldn't hold a good group as seen on a shooting range. Elongating the pin holes fixed the accuracy problems. First hand experience convinced me , elongation works. Most "how to build m/l's" manuals have the elongation info in them as well.

I dont think many people understand what elongating a tenon pin hole means, my personal opinion. I’ve had several guns sent to me as kits where the underlugs were ay over slotted , then drilled out to use a bigger pin only to remove too much wood from the stock.

It’s just not clear to most that the elongation is only a few thousandths of extra space between the lateral sides of the pin hole.

I know several builders that loop their tenons, rather than leave them with square corners, i dont’ do this but according to them, it protects the stock.

 

[FlinterNick]

I have read in Shumway’s books that some old guns he examined with no slots in their tenons had fore-stocks pulled apart by up to an 1/8”. There must have been a lot of recoil and pressures from the barrel back in the day? Or maybe the stock wood expanded and contracted over time?

I work mostly on military arms, the military arms I’ve disassembled don’t have elongated pin holes, on brown Bess’s, french guns, Dutch guns etc. The military rifles i’ve disassembled used keys.

Two early 1728 Brown bess’s had slotted lugs where the thimble tenon fit in-between the lugs, this was not a practical design and impeded thimble placement, so they deleted it on the subsequent models.

Most other model tenon’s were shaped as loops with pins (wire) ranging in diameter from just under 3/32 to 1/8, not all pins were equal diameter also, none of them were elongated. My opinion is that this likely didn’t matter much to the ordinance departments that was building the guns, they just wanted as many made as possible, especially in times of conflict.

One 1760 fusil had brass underlugs, that were also looped.

Now if the experts are saying you should slot the underlugs, then you ought to do that, If i were to do it, i would use hand tools, no power tools.

 

[French Colonial]

Another reason to slot them is they can rust in place if the pin is tight in the hole.

I rescued a basket case Dixie TMR that the rear and middle pins were rusted in place, I managed to get the rear pin out finally with a punch, the middle pin I had to cut out from the ramrod grove with a Dremel.

 

[James Kibler]

I dont think many people understand what elongating a tenon pin hole means, my personal opinion. I’ve had several guns sent to me as kits where the underlugs were ay over slotted , then drilled out to use a bigger pin only to remove too much wood from the stock.

It’s just not clear to most that the elongation is only a few thousandths of extra space between the lateral sides of the pin hole.

I know several builders that loop their tenons, rather than leave them with square corners, i dont’ do this but according to them, it protects the stock.

Absolutely not. I go through thousands of stocks each year and can assure you movement can be significant. I would suggest at least one pin diameter fore and aft of the pin. Listen to professionals and highly respected top builders. Why I keep preaching I sometimes wonder…

 

[FlinterNick]

Absolutely not. I go through thousands of stocks each year and can assure you movement can be significant. I would suggest at least one pin diameter fore and aft of the pin. Listen to professionals and highly respected top builders. Why I keep preaching I sometimes wonder…

No l only drill the pin hole, but again I only build for me and they’re military guns. I suppose if i had wood that isn’t completely dry I would elongate the slot on the underlugs. But l have never had one crack.

When I get around to ordering your colonial long rifle I will absolutely follow your steps on elongating pin holes.

 

[wiscoaster]

..... Why I keep preaching I sometimes wonder…

A sentiment shared with all kinds of preachers I'm sure. But keep preaching. He that knows the truth has a duty to preach it to those that don't know.

 

[Eric Krewson]

I learned about tight pins this past year; on my last build I drilled the front pin hole a little askew instead of 90 degrees, I slotted the pin hole but still had a pin that was hard to drive in. When I shot the rifle, it was a real dog, terrible accuracy. It was a Bobby Hoyt re-bore so I immediately blamed the barrel.

This was my pre-carve from hell rifle, looks didn't matter so tried redrilling the pin hole correctly just to see what happened. I could push the pin in and out with my finger after re-drilling.

I tested the rifle again, it shot a tight cloverleaf at 50 yards, nothing wrong with the barrel but the builder had a thing or two to learn.

 

[Onojutta]

I learned about tight pins this past year; on my last build I drilled the front pin hole a little askew instead of 90 degrees, I slotted the pin hole but still had a pin that was hard to drive in. When I shot the rifle, it was a real dog, terrible accuracy. It was a Bobby Hoyt re-bore so I immediately blamed the barrel.

This was my pre-carve from hell rifle, looks didn't matter so tried redrilling the pin hole correctly just to see what happened. I could push the pin in and out with my finger after re-drilling.

I tested the rifle again, it shot a tight cloverleaf at 50 yards, nothing wrong with the barrel but the builder had a thing or two to learn.

For those who might still be questioning the need for slots, what he described has to do with barrel harmonics which is a separate but equal reason to provide slots.

 

[FlinterNick]

A sentiment shared with all kinds of preachers I'm sure. But keep preaching. He that knows the truth has a duty to preach it to those that don't know.

I suppose it depends on the preacher whose gospel you follow. Mine says for his kits, do not slot just drill. I trust him, he’s come through with replacement parts when needed on his own warranty and I’ve never had to ask.

 

[FlinterNick]

For those who might still be questioning the need for slots, what he described has to do with barrel harmonics which is a separate but equal reason to provide slots.

Not questioning the need, just saying I’ve never had a problem with unslotted lugs on my own kits. I offered my own method which i adopted from my teacher who has been building guns for 50 years, he’s showed me original muskets and rifles that have no slotted lugs, just an observation.

Ironically i do have a fusil here by a professional builder with slotted lugs that broke off and or were over drilled, and the stock is cracked under the forearm, however i think teh stock broke because a wooden rod was swapped out with a 1/4” steel rod without having some type of rammer spoon securing it and the forearm channel area is milled out a bit too much.

the owner asked me to put on a new set of lugs, and YES I will slot them because they were slotted to start with.

 

[FlinterNick]

I learned about tight pins this past year; on my last build I drilled the front pin hole a little askew instead of 90 degrees, I slotted the pin hole but still had a pin that was hard to drive in. When I shot the rifle, it was a real dog, terrible accuracy. It was a Bobby Hoyt re-bore so I immediately blamed the barrel.

This was my pre-carve from hell rifle, looks didn't matter so tried redrilling the pin hole correctly just to see what happened. I could push the pin in and out with my finger after re-drilling.

I tested the rifle again, it shot a tight cloverleaf at 50 yards, nothing wrong with the barrel but the builder had a thing or two to learn.

Nice work ! I enjoy following your posts Eric

 

[mtsage]

Not being sarcastic here at all. I just need to understand this better. How can the stock move when pinned thru a elongated hole when the tang is bolted/screwed into the stock? The breech plug/tang is threaded into the barrel. What am I missing? Thanks in advance.

 

[2 shots]

seems its about the thin forearm wood moving putting pressure on the barrel. i think some are saying its more of an accuracy thing, not always about spitting. i would guess it has a lot to do with climate also.