S.C. on SMLE barrel

Are your gauges calibrated annually Son? Ours came back from calibration, sealed in a plastic envelope with the calibration sticker. But if they were old and not clearly marked, as soon as you took it out of the envelope................ Guess what? Back to square one

OK- I'm getting confused now. Is the "S.C." stamped on the barrel not indicative of a shortened "Lead" or "forcing cone" in response to change in bullet design? After reading this thread I spent an hour scanning all the usual references and this appears o be what is implied although I couldn't find any statement of exactly when it was first applied to SMLE barrels. Many references to accuracy experiments (in part pre MkIII) where a shortened lead was tested and, generally, found beneficial. I think jargon is starting to cause problems here?

Ridolpho

Back to my early books. The SC stands for Short Cone. I'd have to start rummaging through some much older EMER's to give anything further........

Er........., soprry, I meant small cone

So, nothing to do with the "small cone" on the illustration of the .303 chamber previously mentioned?

Ridolpho

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Originally Posted by Ridolpho

So, nothing to do with the "small cone" on the illustration of the .303 chamber previously mentioned?

Ridolpho

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The only reference Ian makes in his book (that i can find) that describes in any detail the "Small Cone" is in the Markings section page 576 TLE.
"S.C. Barrel, behind rearsight. Small cone increased; lead from chamber to rifling for MkVII ball"

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Originally Posted by Ridolpho

OK- I'm getting confused now. Is the "S.C." stamped on the barrel not indicative of a shortened "Lead" or "forcing cone" in response to change in bullet design? After reading this thread I spent an hour scanning all the usual references and this appears o be what is implied although I couldn't find any statement of exactly when it was first applied to SMLE barrels. Many references to accuracy experiments (in part pre MkIII) where a shortened lead was tested and, generally, found beneficial. I think jargon is starting to cause problems here?

Ridolpho

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If you have a look at the diagram of the chamber in post #4 from MkVII and re read the bit in blue from my first post, you will have the official explanation of the mark "SC".
Still hoping Bruce in Oz can come up with more marked chamber diagrams to confirm, and anyone with documentation on this "LC" mark... even as applied to the Ross rifle as suggested, maybe then 5thBatt will be able to "unconfuse" the thread on the other board...

Peter, our fixed gauges are not calibrated, I have not seen any requirement written anywhere to have them done. If damaged they are simply replaced. I keep every one that isn't easily identifiable in a marked bag.

drawing source was the Textbook of Smallarms (1929).

Thank's Son! What had confused me was the definition of the "S.C." marking, in a couple of references, mentioning or alluding to some affect on "Lead" (as in Skennertons glossary). Am I correct in saying the increase in diameter of the "small cone" has no affect on "Lead"? Furthermore, it appears "Lead" was dealt with pre-1910 in the SMLE as there is a 1908 entry in the LoC's directing new manufacture of barrels for M.L.M. and M.L.E. rifles and carbines, etc, to incorporate a "Lead" of 0.6 inch rather than 0.8, "similar to that of Rifles, short, M.L.E.

Ridolpho

Yes, Ridolpho, I think thats a pretty accurate summary of where we are at this point! :thup:

I have three full DVD's here from an old retired armourer mate. Lots of his books, notes and other info he's spent many hours scanning and uploading. I will take some time and go through them looking for diagrams and info that might be pertinent to the discussion and post them here.

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Originally Posted by Bruce_in_Oz

That clears that issue up, but what was going on that the "shoulder" needed adjusting?

Was it something to do with providing clearance for "mud" or dubious wartime ammo? Being a rimmed round, you can have a "generous" shoulder, and even body clearance (instant "improved" cases), and no problems with headspace / striker protrusion, unlike a rimless model in which length from head to shoulder datum is critical..

As a side note, what is the source of that illustration?

Back to exploring the crypt for the various .303 chamber drawings.

Does anyone have barrel / chamber drawings for Bren and Vickers, as well.

There seems to have been a lot of creative engineering in these regions for a long time, but even drawings for 7.62 NATO barrels show subtle differences between machine gun and rifle chambers.

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In regard to your first question my thought would be that a tighter cone would help to center or align the case in the chamber, and therefore the entry of the bullet into the rifling - assuming of course that the bullet and case were in fact aligned during manufacture!