front swivel lug?

[Doc Arroyo]

I recieved some parts for my friends Jeager. I cut the dovetails and fit the barrel lugs. Then I took a third look at the lug for the cross bolt for the front sling swivel...the danged thing has to be twice as deep at the base then the barrel lugs!

Does the sling swivel take that much force? Or should I file the base down to match the depth of the barrel lugs?

 

[rich pierce]

I'd not make the dovetail deeper because it looks like they intended it that way. Only on the front sight is depth really controlled by the design of the "thingy" that goes in the dovetail (cause you want the sight down tight on the barrel).

That being said, yes, the lug takes a lot of force and leverage and I would use a lug that covered a large area and was quite thick in the plane that is parallel to the bore. Then I'd solder it after dovetailing it. Tin both, heat both, drive it home.

 

[Mike Brooks]

I'd cut the base down to 1/16" thick.

 

[Erzulis boat]

I just did mine on the Trans rifle.

I machined the underlug from steel, and it is a tad more beefy than the pin lugs.

The depth of penetration into the web of the ramrod channel/barrel inlet is also slightly deeper, but does not protrude into the ramrod channel thus exposing itself.

The fastener diameter was .129, so you want some meat surrounding this in all directions.

If you drill the hole with about .050 of wooden web above the hole towards the barrel, it will be perfect. My ramrod groove is quite close to the underside of my barrel, and by being very careful, everything fits easily.

The real "maker or breaker" of this attachment relies on the uniformity and precision of the sling throughbolt hole.

If the hole is very accurately on size through the wood AND the lug, the attachment will be the most secure, as this allows the entire span to support the crossbolt.

If the steel lug, for example, is on size, but the wood hole is oversize, the swivel will rapidly become loose. and consequently distort the hole through the steel lug.

This is very important, as the underlug is narrow. Mine was machined .090 wide, but this is still narrow.

I used a .129 drill, which was my bolt diameter, and the fit is perfect with no slop or play whatsoever. This will maximize the life and function of the swivel.

 

[Mike Brooks]

Ok, that's cool everything is tight.....What happens when your stock or barrel starts expanding or contracting? ( I have the answer if you want it. :winking: )

 

[Erzulis boat]

If that was your concern, you would have to cut an elongated hole (slot) parallel with the bore into the lug, but leave the wood's throughhole precision. The relief for the underlugs wood also have to allow this movement, of course.

But likewise, all of your barrel retention pin holes would also have to be done this way, or else it is merely "eye wash".

Back to "eye wash", if you cross drill your pin holes, relieve the wood around the lug, but do not elongate the pin hole................once again........eye wash.

And, while I am thinking about it, another way would be to relieve the lug left and right perpindicular to the bore, inducing a span of un-supported pin, as this would allow flex in the linear plane (the most differential plane in regards to thermal expansion, AND wood expansion/contraction) and the pin's small diameter would allow some movement, while the throughhole could remain precision.

 

[Mike Brooks]

And, while I am thinking about it, another way would be to relieve the lug left and right perpindicular to the bore, inducing a span of un-supported pin, as this would allow flex in the linear plane (the most differential plane in regards to thermal expansion, AND wood expansion/contraction) and the pin's small diameter would allow some movement, while the throughhole could remain precision.

You wouldn't happen to be a rocket scientist would you? :haha:

 

[Erzulis boat]

You know what, Mike-

I have been trying to figure out this whole tiny diameter pin thing, and I think these Old Timers might have been smarter than some give them credit for.

Just the tiny diameter of the pin, being that it flexes easily would allow for a lot of movement front to back AND up and down, just like making the forend very thin minimizes the force that it can exert on the barrel, and vice versa.

The relief around the lug, if using a 1/16" pin could be very small and still allow all kinds of movement via pin flex exclusively.

Maybe a lot of the Art is also super sophisticated engineering? :hmm:

 

[Stophel]

The pins WILL NOT FLEX!!! No matter how small they are!!!

Wood does not expand and contract along its length. For something like a walnut or cherry stock that is straight grain in the fore end, slotting is theoretically unnecessary. The problem comes with curl or when the grain is otherwise crossing the direction of the fore end.

Several years ago, I was doing a rifle and had the barrel in and tenons done and pinned. The weather was our normal incredibly humid condition. I took the barrel out and set it aside to work on another part of the gun. During that time, the weather changed and we had a spell of unusually low humidity. I went to put the barrel back in the stock, and the two front tenon pins would not line up! In a few days, the fore end had shrunk almost 1/16"!!! There's NO WAY that the pins could possibly flex that much.

Slot the tenons if there is any curl or cross grain in the fore end...even at a slight angle. If the grain is straight, it shouldn't actually need it. I have another that I did MANY years ago with a walnut stock and the tenons are not slotted, and it's still fine, but the grain runs straight through the fore end.

 

[Erzulis boat]

Wow.

A full 1/16"! That is incredible.

I have done some "Manlicher" (sic) style forends on modern cartridge guns over the years (Claro and French) with very precision front sling crossbolts, that I even sleeved with ultra thinwall medical hypodermic tubing that are still perfect (late 80's - early 90's), but if you are reporting a full 1/16"- then my hypothesis is undoubtedly incorrect.

Furthermore, what would have been the result, had the barrel been inserted and pinned during this radical climactic change?

Perhaps a seperate post is in order.


I think that living in California (the climate) has me spoiled, as nothing moves at all.

I am glad you posted this information.

:hmm:

 

[Stophel]

If the wood in the fore end is straight grain, it can't shrink or expand (though I do think that over LONG periods of time, wood shrinks regardless of humidity..). Curl or cross grain is the culprit. You get sideways grain stacked up all along the length of the fore end and THAT will expand and contract.

The shorter the stock, the less it will expand and contract, naturally. Two stocks cut from the same piece of curly wood will expand and contract in length differently if one has a barrel of 42" and the other a barrel of 28". The short barrel stock simply has less grain to expand or contract than the longer gun does. The longer the stock, the more the change can add up.