back action lock questions

[Hungry Horse]

 I have an antique, left hand, back action, lock, that has never been on a gun. It is 5-1/2" long with a 2" hammer throw. This is a big lock. I believe it was originally designed to be the left hand lock, on a massive double gun. I intend to use it on a rifle for my left handed nephew. My question is, how do I support the drum, and nipple, to keep this massive lock from shearing it off from the barrel? Also, what is the best way to anchor the front of the lock so it doesn't break its mortice when the hammer falls?

                  Hungry Horse

[Bob Roller]

HH,
That big back action lock is made to be used with a bolster.
A drum and nipple is a bad idea from the outset with a bar lock.
I think there are left hand bolster breeches in some catalog,maybe TOW.

Bob Roller

[Hungry Horse]

Bob;

  My reason for considering a drum and nipple is mostly do to the fact that this lock is much larger than anything on the market, with a very powerful mainspring.  None of the hooked breech plugs I've seen have any place to anchor the forward lock bolt in anything other than wood. Also I fear getting the hammer to contact the nipple may be a problem, due to the size of the hammer and the long throw. This hammer has a 1/2" hammer face, which will no doubt mean lots of grinding and reshaping the flash fence, and possibly other parts of the plug.
 Would using the largest drum available, or making one, that pretty much fills the barrel flat, with the largest diameter treaded section possible help at all? Or, am i just barking up the wrong tree? 

               Hungry Horse

[Captchee]

I have a couple match sets of  what sounds like  much the same lock s or at least a match set of  left and right hand large back actions .
As Bob  mentioned , they are meant to set to a bolster  or standing breech .

 If the lock has never been  fitted to a stock the front  mating edge of the lock should be near 90 deg to a centerline of the lock . This allows you to  fit the lock to many  different   drop angles  by matching the angle of the seat on the bolster  with the intended angle of  the wrist .
  Also the  bolster for these large locks did not have a 90 deg   relief  like on a common back action shotgun . Instead the  bolster carried a slight slant to the  edge of the relief .  This keeps the lock from being driven down   and splitting out the mortise . IE the front edge of the lock is supported by the bolster or standing breech .
 The lock bolt placement is  most commonly   forward of the  tumbler . A wood screw secures the tail of the lock

 Now that being said , there was a company ?? I forget who now , but they made a large back action that  used a coil spring for a main spring . The lock plate  is rounded at the nose  and meant to be completely  inlet  in wood . Thus not supported.
As I recall these were rebounding locks  much like one would find on a Old  back action  rabbit ear shotgun . They were just larger . I think I may have a matched set of those out in the shop as well ??

Setting them up was alittle difficult as you had to  make sure that  the hammers  made  contact with the nipples after loss of spring tension or you could run into issues with damaging the nipples or busting out the mortise .  The later not being IMO to big an issue as these locks were  for large  , heavy framed guns like 2 and 4  bores  . Thus while the locks look big  now , they are not  in comparission to their intended home .

 They also mounted with a bolt forward of the tumbler and a wood screw in the rear 

[Bob Roller]

HH,
This sounds to me like an attempt to make a rifle out of incompatible parts. A drum and nipple MUST be supported and a bar lock is the only practical way to do it.I think we have all seen a caplock rifle with a drum and nipple and a back action lock and the problem is that after a long (or short)period of time,the last thread in the drum can crack and the drum blows off.Sixty four years ago I had this happen to me and my right ear rang for a couple of days.The lock on this gun was a small one,proportionate to the rifle and when the drum blew,the threaded part was still in the barrel.I took it to George Killen,a local gunsmith and he got the threaded piece out but told me the whole set up was a trap and didn't replace the drum and nipple with a new one.

Bob Roller

[Hungry Horse]

 The forward edge of this lock is square as you mentioned. Its a half inch from the square forward edge of the plate to the center of the hammer face, at rest. What would be the best way to get a good tight fit between the plate and bolster? I think any play in this spot, will result in a broken stock. This monster has a flat spring, with a stirruped tumbler, that is 3/8" wide and 4" long. This thing can generate a bunch of energy.

                Hungry Horse

[Hungry Horse]

 Thanks Bob, I will benefit from your unfortunate experience, without trying it myself. Do you have any ideas on fitting the lock and bolster?
 Also since this gun will be almost exclusively a big game hunting rifle, and the lock has no fly in the tumbler, would you think it better to use a single phase double set trigger, or go with a simple trigger. Most of the hunting will be in the Rockys during the colder months.

                    Hungry Horse

[Acer Saccharum]

If the lock is new old stock, it could be that the front square section is designed to be filed/ground to fit against the bolster.

As others have said, nix the drum.

[Bob Roller]

HH,
Get a TOW paper catalog with full size pictures are lay the lock along side of the breech you select and see if it can be filed to align the cup of the hammer with the nipple.I wouldn't think of a set trigger on this rifle.

Bob Roller

[Hungry Horse]

 Thanks guys, I will go with the simple trigger, and patent breech.
  And thank you Bob for reminding me about the full sized illustrations in the Track catalog. I use them all the time for lock sizing, but forgot that the breech plugs are full sized as well.

             Hungry Horse

[gunmaker]

You can weld on a piece of metal to front of plate and contour it to fit a drum,  but patent breach is stronger....Tom

[Captchee]

I   still wouldnt use a drum without a heavy suport Gunmaker .
 if its the locks i think he is speaking of , they are mosters and  would bust a drum right off a barrel in quick order just as BOB sugested .
. Even if it were of rebound type , the hammers are still large  and if not set up just right , would IMO also result in damage to the drum from just the repeated weight of the hammer hitting the un supported drum

[Hungry Horse]

 I think the lock you mention is the one I have. Turner Kirkland got them from an old warehouse in Belgium, I think. A lot of the other stuff in this lot of parts, was originally designed for the African trade. So it is quite possible that whatever gun this was designed for, was as well. I originally thought of making a late percussion trade gun out of it, but when the nephew said he was looking for a robust left handed, big bore, hunting rifle, I knew where to get the lock.The barrel is a 1"x35"x.62 cal. in a 1 in 72" twist, made by Orion barrels, just about the time they went out of business. The pattern is roughly taken from a big bore hunting rifle made by Joseph Craig of Weaverville Ca. He built guns to hunt bear, elk, and claim jumpers,at the very end of the muzzleloading era.

                   Hungry Horse