Hooked breech with drum?

[Scota4570]

I was about to start machining a flint style hooked "patent" breech to use on a percussion Leman.  It occurred to me that I could have interference to lifting the barrel out at the front of the drum by the lock plate recess.  Anyone have experience on this?

[Bob Roller]

I was about to start machining a flint style hooked "patent" breech to use on a percussion Leman.  It occurred to me that I could have interference to lifting the barrel out at the front of the drum by the lock plate recess.  Anyone have experience on this?

There should be no problematic recess.If it's a 1/2" drum it should be no deeper than 1/4" and
even if it's a bit deeper it still will not catch the drum.
Bob Roller

[Scota4570]

Thanks for the quick reply Bob.  I'm  having a hard time wrapping my head around it. 

As I see it, the lockplate recess matches the drum perfectly.  The drum is buried 1/2 of it's diameter in the lock plate.  The barrel and drum must move forward to tilt out.   Once over the center-line of the drum it should not matter,  I get that.  The initial movement will have a forward component. 

 I suppose if it catches a little I could undercut the drum radius on a line tangent to the top edge of the back to the barrel top eliminate any hesitation it it shows up.  It would not show anyway.   

[shifty]

   That drum looks far back.

[Scota4570]

   That drum looks far back.

It's a "Patent" breech so it works that way.  The distance from the rear of the standing breech to the back of the drum is similar as with a fixed plug.  It could be fudged maybe a bit further aft than a regular plug though.

 

[longcruise]

I was about to start machining a flint style hooked "patent" breech to use on a percussion Leman.  It occurred to me that I could have interference to lifting the barrel out at the front of the drum by the lock plate recess.  Anyone have experience on this?

I have a rifle that catches like that but it's such a nice fit to the lock that rather than mess with it (always risky in my hands) I remove the lock first.  Not an inconvenience since I always remove the lock to clean.

[smylee grouch]

I have used that set up on a couple of rifles and I relieved the front 1/3 of the U notch and filed down the front of the lock bolster just a tad . The drum still hit bottom in the U notch to help support it. I only took enough to make a very slight almost un seen gap and I rounded the top of the forward edge of the bolster.

[okawbow]

I built a double barrel hooked breech rifle with drums. The drums fit nice and tight. The hooks are short and allow the barrels to drop right in.

[Bob Roller]

I have started a flintlock half stock rifle with a chambered breech that was ALMOST
too short**.I am using an L&R late English lock with my internal mechanism.I had to alter
the flash fence or shield to nearly vertical to accommodate this stupid error but it doesn 't
look bad so I will continue with the project.The barrel is a GM 50 caliber an inch across the flats
and 33"long in black walnut..I am thinking of a English style game keeper's gun or park rifle
like Mike Brooks showed a long while ago.The good profile and simplicity has a strong appeal
to my lazy nature.
** Integral tang all milled from a piece of 8620.Reminds me of some I made in Bill Large's shop
many moons ago.

Bob Roller