Hello, all knowing, all seeing Highwall knowledge base!

I got my .32-40 #3 barrelled 1885 (1893 mfr) in - project underway. It arrived with a cutaway in the forend just ahead of the receiver measuring about 3.135" long by .25" down which exposes a row of 5 holes drilled in the left side barrel flat (the one perpendicular to the top). The c-t-c distance between the 1st and 5th holes is about 2.625". The 3 holes between them are spaced somewhat irregularly. They appear to be drilled 1/8" to varying depths. The forward most hole is .125" deep, the next is .095", the middle hole (centered between forward and rear most) is .125", next is .075", and rearmost (nearest the receiver) is .125" deep.

I don't have a thread gauge, so no guesses there.

Two questions - 
What did these holes serve?

Is my #3 octagon barrel materially weakened by them? I expect to shoot at pressures well below 40000 - am I going to be okay here? 

I expect to use a Lyman Targetspot and I can't imagine a use for these holes, so I expect to plug them and cover up with a replacement forend.

Any ideas/help/speculation ?

Thanks.

PM

Hole depths are accurate +/- .002. Barrel is a #3 full octagon. Seems to me same as if drilled and tapped on top. Just can't imagine a side mount, but someone out there will be particularly familiar.

Anyone?

PM

In Campbells book, volume II, pages 214 & 215 describes an offset scope mount.  This one is mounted on the normal scope bases attached to the top of the barrel. The mount is then constructed in such a way as to move the scope off to the side. This is the only one I am aware of in either of his books.

Not to be too nosy, but why do you want a Mann-Neidner firing pin?   ???  With a .32-40 and any normal loads that round would be likely to contain, even the old large firing pin would be fine, and the small pin late style would have plenty of strength.  I would hate to go to all the work of making and fitting the Mann-Neidner type conversion when it really isn't necessary.  BTW, one reason the original works so well is that it has positive retraction from the lever link...the Mann unit depends on the action of a spring.

If you are converting a rimfire block to centerfire, you can actually make and install a little bushing on a drill press if needed (and then I would set it up for the later, small pin firing pin if it were me.)  What part of the country are you located in?  There's bound to be somebody nearby who can help you out.

Regards,
Froggie

PS  As to the holes being for the mounting of a loading block, I had one musket that had two holes in the wood of the fore end for that purpose, but I have never seen anyone drill a barrel to mount their block...but shooters do strange things!