Martini Henry 577/450 bore

[gazz]

Hi
A friend has a M.H. with what seems to be a choked bore. When he slugged the bore, the first couple of inches at the muzzle were tight, then then the slug almost fell through the rest of the bore.
The barrel is an original 577/450.
I have read a bit about M.H.s but never heard of this before.
The bore is in reasonable shape (not rusted out).
Has anyone else come across this before?
At first I thought it might have been the result of tapered rifling but if this was the case, the land to land bore would be uniform and would hold the slug tight (I think).
Any answers?
gazz.

[sharps4590]

I've not heard of a choked bore on the M/H either but from your post it certainly seems it may be.  Over the years I have noticed that when slugging a bore it gets considerably easier after the first few inches but I've never had one nearly fall thru as you described.  I was thinking you could slug it from the breech end but it seems that would take some doing with the M/H unless one took the barrel off.

I did work with a dear departed friends' M/H a few years back and developed some fairly good black powder loads for it.  If you have need for such info let me know and I'll dig out the data.  

Vic

[Double D]

Sorry Gents it took me 3 months to find this message.  I don't wonder down here that often.

The Martini Henry has a  7 groove Henry rifled barrel of 1 turn in 22 inches.

The nominal bore is .450 and tapered.  A .449 plug gauge will run the fill length of the bore.  A .451 gauge will be rejected or not run full length.  A .451  plug gauge will run from the breech end 4 inches up the bore.  A .450 guage will run  8 inches up the bore from the breech end.  The rest of the barrel,  about 26 inches,  is cylinder.   The grooves in the  tapered section are  .009 inches deep. The cylinder section grooves are .007 deep.

The MH MK I, MK II and MK III like bullet .464 or morte in diameter.  The Mk IV like.468