bullet size in Sharps Straight

[Lamar90]

I have noticed that all of the sources for cartridge specs that i have looked at show .451 bullets for 45-100/110/120 cartridges (as well as a couple of others). Is this the actual groove dia on original barrels or does the spec. assume bump-up or paper patches?

I have heard at least one person mention seeing a rifle that would only shoot well with .451 bullets, so i know they exist whether such barrels were common or not. In this light, would it be wreckless to chamber a .452 groove barrel for a Sharps Straight cartridge?

[Don McDowell]

Many of the Sharps rifles from the early days are reported to have a .451 bore diameter. Winchester and the government were the ones that supposedly opened the 45 bores to the 457-8 we're used to seeing now days.

[Lamar90]

Thought i would get a quick answer: thanks!

[405]

I have measured a few original PP and plain cast rounds designed for the various Sharps and other cartridges of the day. They seem to be all over the place when compared to the "book" dimensions. Mostly the loaded bullets seem to run somewhat smaller diameter than what we're used to for bullet to bore fit now. Many think this was done to make sure the cartridges/bullets would fit easily into badly fouled or dirty chambers. I guess that sounds as reasonable an explanation as any. The accuracy may have been ok since most used soft lead and would obturate to bore dimensions.

The only original Sharps bore I have had a chance to closely examine and slug is one I own. It is in 40-70 Sharps Straight. The listed standard bullet diameter (for whatever that's worth) is .403". The bore I have is in near pristine condition. The bore diameter is .401" and the groove diameter is .406". The lands are approx. .06" chord width and the grooves are approx. .16" chord width. The bore is 6 grooved.

How that compares to other Sharps' bores? dunno

[NickSS]

Back in the old days bores and bullets varied much more than today. As a result most makers made them undersized so that they would bump up when fired with black powder. Even the famous 45-70 relied upon this as most Army trapdoors have bigger groove diameters than the nominal .457 inch of the bullet. I have six trapdoors and all of them have groove diameters of between .461 and .466 inch.