doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Ithaca NID question

I have several ithaca NID doubles - some of them have a little play when open but when the barrels are closed up they are very tight. Can anyone tell me what causes these to be loose when open and still very tight when closed up?

Thank you,

scott

Rotary bolt. Shooting must put a bit of strain on the piercing in the rib extension but I haven't seen many broken out. Decrepit Foxes also show this trait.

jack

When they they are closed up, the entire length of the barrel lug is sandwiched between the receiver walls. When the gun is open, only a small part of the lug is inside the receiver. I would guess that the further the guns are open, they looser they are. In addition, when the guns are closed, the rib extension would tend to prevent any side to side play and the rotary bolt is also exerting pressure on it. In short, there is a lot more surface area preventing side to side motion when the gun is closed than when it is open.

It is a matter of wedges.

Sometimes unless it's been maintained (righteously greased), the lug is also not a great fit in the channel. Witness some of the peening and punching that's done to make it bear laterally and also upset metal into the edges of the hook.

jack

Many American guns that are not worn in any way have lugs that do not fit in the channel tightly. They come from the factory that way. The "fit" that makes the gun tight when open is the fit of the loop to the hinge pin. The fit of the loop to the hinge pin can be renewed by some home remedies that are nearly invisible and long lasting. The most friendly home method involves trimming a thin shim to fit the loop, attaching it by torch and solder or by high tech adhesive, dressing it to fit and to look invisible as possible. The alternative is to not worry about it.

What Eightbore said.

Imagine just a high spot in the middle of the hook. That would be enough to set the barrels back tightly against the breech face when closed, yet allow the the hook to "rock" on the pin when open. In otherwords, when fitted, it may not have been fitted with maximum contact. I suspect a similar scenario (varying degrees of original surface contact)could explain why some toplevers with rotary bolts move so quickly past center while others with many thousands of rounds through them move very little.

instead of solder or gluing. why not piece the hook?its fairly easy and permanent,welding is also an option and refit. mc

mc - solder/glue of a hook shim is quick, easy, renewable, and reversible. If a fairly hard steel is used for the shim, it can be long lasting, also. A "permanent" fix is preferable, but some guns are marginally worth the cost for such. Almost any gun is worth a home shop shim.