Question on Turning breech plugs

[webradbury]

I'm turning some breech plugs for a double flintlock shotgun build, following Brockway's book. My question is, how much material should be left at the back of the plug, basically how thick should the rear be? I turned a beauty but slipped up and removed a little too much, to my eye, from the back. It is at about 1/8" to 3/16". The plug is 3/4" OD with a 11/32" chamber. And of course the lug is behind this bit of meat. I'd rather be safe than sorry and have already bought more material in case I have to start over.

[D. Taylor Sapergia]

Just use Brockway's book.  There are some dimensions there and his drawings will show you the proportions you need.  Also, I personally work much better from images of the question rather than a description.  So post a pictures(s) for more specificity.

[Scota4570]

I made mine as two plugs that were the same contour as the barrels.  I then soldered a piece of rib on top that I removed from the cut off breech section.

Brockway suggests making one plug that follows the barrel outside contour.  The other plug is made huge.  The extra material is removed to make a rib extension and to allow the little plug to screw past the big one.

If you made the big plug a bit small you may be above to salvage it using plan one above.

[webradbury]

I'll try to post a photo. It's difficult to describe clearly

[L. Akers]

I'm not sure what you are asking either but maybe this description of my plugs will provide an answer.  I made my plugs as Brockway describes.  The outside diameter of the plugs is the same as the outside barrel diameter.  I made my plugs with a length of 3/4" measured from the rear of the barrel to the base of the hook.  The hook length would be equal to the thickness of the standing breech--in my case about 3/8".  So I have a total of 1-1/8" of materiel behind the rear of the barrel. The touch hole liner is centered in the 3/4" long section of the plug or 3/8" behind the rear of the barrel.  I made recessed Manton breeches and the chamber extends to the center of the liner.  Hope this helps.

[webradbury]

This is the plug. My question is have I made the chamber too deep and thus made the rear of the plug weak? The shaded area highlights the chamber (unshaded area). The back wall at the rear measures a hair over 1/8" thick.

[Dennis Glazener]

The shaded area highlights the chamber (unshaded area). The back wall at the rear measures a hair over 1/8" thick.

That would be .125". I am no builder of double barrels but I don't think I would want mine that thin in that area. For barrel lug dovetails most say .100" is safe but we are talking several inches in front of the firing chamber. Personally I would want more but that's me.
Dennis

[P.W.Berkuta]

I'm with Dennis on this also. Since you can redo it there is no problem - just time and with your face at the back end of the breach I would make it with more "meat" back there - also square or round off the end of the chamber not a drill point as the drill makes (shown) - (grind a drill or use an end mill to produce a flat or round face - just me).

[webradbury]

My thoughts too. Oh well, practice makes perfect

[L. Akers]

I have made lots of flint "patent" breeches--mostly of the Nock type and I like a minimum of 1/4" of steel around the recesses.