Original 1863 Sharps Conversion Bore Diameter?

[Blackpowder Burn]

I have acquired on semi-permanent loan an original 1863 sharps carbine that was converted to 50-70.  This is one of the rifles converted in about 1868 and the barrel relined.  Given that it has 5 groove rifling, I can't get an accurate bore diameter by slugging.  Can anyone recommend the proper sizing diameter for bullets?  Based on what I've read, it should be about 0.515 - does this sound correct?  I have to either order a sizing die for my Star lubrisizer or shoot as-cast if of acceptable diameter from the mold.

I've purchased a few 425 grain 0.515 bullets from BAC, but accuracy is nonexistent at present.  The bore is a little rough, but has prominent rifling.  My loads to date have consisted of the above bullet with 60 and 65 grains of Goex Express FFg over a 0.030 fiber wad.

Thanks for your help.

[Trailrider]

Your statement that the carbine has five (5) groove rifling raises a yellow flag, because the relined carbines have three (3) lands and grooves in the liners!  I can't find a reference in either of the late Frank Sellers' books right now, but I did find the reference to the order from the Ordnance Dept. to Sharps Rifle Co., that if the .52 caliber percussion barrels had groove diameters NO LARGER than .522", then they were to ONLY have the cartridge conversion (new breechblock, modified hammer, firing pin and extractor installed.  Have you tried to slug the barrel with a .515" bullet and see if the impression left by the rifling is very deep?  If the lands barely make an impression, then you probably have an unlined barrel.  Another way to possibly check if the barrel is lined or not is to look at the muzzle under a magnifying glass and see if you can see the ring joint where the liner is brazed to the barrel.  You can't always see the joint on a lined barrel, but if there's no ring, it might back up the other assumption.

So far as a bullet is concerned, you may need to have a mould made up or locate someone who can cast a hollow base bullet with a diameter as large as you can chamber, but leaving a little clearance between the loaded round and the chamber wall. A chamber casting using Cerro-Safe low-melting point alloy (Brownell's or Dixie Gun Works) will also help determine the maximum diameter the loaded round can be at the neck.

Does your carbine have a spring-loaded firing pin, perchance?  If so, it is one of the scarcer early conversions.  Be cautious about shooting this marvelous piece of history, Pard!  The action is, after all, about a century-and-a-half old!

BTW, is this a M1859 or M1863, as marked on the barrel?  Any other interesting marks on the stock?  Any initials or names carved in the stock?  If these carbines could only talk...

[Blackpowder Burn]

Trailrider,

My apologies, but I made a mistake in my post yesterday.  I meant to say the rifle has 3-groove rifling.  It is a model 1863 and has the cam operated firing pin. 

The rifle is in amazingly good shape, I've had it thoroughly inspected.  And I will only shoot black powder ammunition in it.  It won't see a lot of use, but I want to be able to take it out occasionally and put a few rounds through it.  As you say, it is a very special feeling to be able to shoot a rifle that saw service in the Civil War.

[Trailrider]

Aggie D,
Thanks for the update, Pard.  Even with the 3-groove rifling (which was pretty standard on most of the government approved equipment, I still think there is a possibility that the barrel of your carbine might be one that was "within spec" of .522, and thus wasn't relined.  I'd still try to slug the bore.  As I mentioned, if the .515" bullets don't seem to be creating much indent, it is probably undersized.  Spec for rifling depth on all these .50 cal. barrels was .005", so even without being able to measure across an uneven number of grooves, you might get an idea if the groove diameter is larger.  You might check with a local machine shop or gunsmith and see if they have the means to measure across the uneven grooves.  There is a way, but you have to use a special v-block and wire rods, but it has been decades since I did that, and I can't recall the exact procedure.

Again, the easiest solution might be to have a hollowbase mould made up and shoot those with BP loads.

[Sir Charles deMouton-Black]

http://www.neihandtools.com/catalog.html

Go to page 14.

.514-325 #378C  Lakota Spencer.  Looks awfully like a Big-Loob?  has a hollow base.

.525-395 Spencer

[Montana Slim]

Not a cartridge conversion, but the following video is my son trying out grampa's CW Sharps (1863).

This gun appears to have been used a great deal, but not abused & still functions perfectly.....too bad I can't get Lawrence Patent primer pellets.

The bullet I'm using is a 395 (approximate) .535 heel-type, loaded with loose powder in this video, but we've made a lot of paper cartridges, too.

Slim

[Blackpowder Burn]

I read somewhere during my research (can't remember exactly where) that the original barrels were 5-groove, and all of the lined ones were 3-groove.  I thought it was in Sellers book, but can't seem to find it now.

Sir Charles - thanks for the information.  That looks verrrrry interrrrrrresting.  That might just fill the bill.

[Colt Fanning]

Howdy,
In reference to your statement "accuracy is non existent".
I shoot a Model 1866 Springfield  which like your sharps was sleeved to 50-70 with a 3 groove liner at Springfield in 1866-1867.
The groove diameter is .515. I began shooting with 50 grns of swiss 1.5, a .512 340 grn bullet in a Bell 50-70 case and
the result was about a 3 foot pattern at 100 yards.  Noticing the huge expansion of the brass, I made some measurements of the chamber and found that it was .060 in. oversize at the end of the 50-70 brass and had .875 in. of free space.  I concluded
that I would be better off to start with 50-90 brass and then found that it would chamber a 50-90 round with .125 of free space and the chamber was only .015 in. oversize at the end of the 50-90 brass.  Shooting a .515-450 grn bullet cast from
hard Lyman #2 alloy and 50 grns of Swiss 1.5,F the pattern decreased to 8 in.  I then seated the bullet out of the case with about .010 in. of free space and the pattern dropped to 4 in. at 100 yards.  I later found on the trapdoor discussion group that this oversize chamber is common on the 1866 Springfield and most of their shooters use 50-90 brass and trim it down if needed.  In short your accuracy problem may be due to an oversized chamber.  I can't imagine why Springfield thought this was ok.
Regards
Cplt

[James Hunt]

I guess I don't have any technical advice for you beyond encouragement to keep at it. Below is my 68 conversion carbine, rough on the outside it does have a minty bore. Like you I use BAC .515 425 g. grease groove bullets, 1-20, no wad, and 65 grains 2f Goex. I make no effort at any extreme loading technique. Unlike you I get what I consider acceptable accuracy. I have never attempted anything off the bench with it, but have shot it many times offhand and with those tiny Lawrence sites and short barrel I seem to average about 6 - 8 inches consistently. That is with my eyes and shooting skill, both less than most.

An original .50  gvt round drops right in (won't fit in my Shiloh), and the ammunition I load certainly seems like it is pretty loose in that chamber, but that bullet must bump up pretty well. I can shoot 20 rounds from that thing without any bore cleaning technique and honestly, the group size seems the same. The rounds still drop in the chamber without any effort. I don't know how far I could push that as I have never shot more than 20 at one time. They extract easily.

It is a great little gun, my only complaint is that it shoots 9 inches high on the lowest site setting and I have no desire to change its original architecture to bring it down.

[Fox Creek Kid]

Colt Fanning, were all your reloads done using a HARD cast bullet? I've never heard of a 50-70 grouping as bad as yours. Then again, I am not familiar with the '66 chambers. Also, your rifle has a 1 in 42" rate of twist which is best for the 450 gr. Gov't bullet. I believe the Sharps 50-70 conversion carbines have a 1 in 48" ROT as did their percussion guns. The '74 Sharps used a 1 in 34" ROT in the .50 cal. I have a Garrett Sharps conversion carbine that I had relined to a 1 in 32" ROT and it shoots the lights out. The 1 in 20 tin/lead alloy seems to shoot the best in most guns.

[Trailrider]

I guess I don't have any technical advice for you beyond encouragement to keep at it. Below is my 68 conversion carbine, rough on the outside it does have a minty bore. Like you I use BAC .515 425 g. grease groove bullets, 1-20, no wad, and 65 grains 2f Goex. I make no effort at any extreme loading technique. Unlike you I get what I consider acceptable accuracy. I have never attempted anything off the bench with it, but have shot it many times offhand and with those tiny Lawrence sites and short barrel I seem to average about 6 - 8 inches consistently. That is with my eyes and shooting skill, both less than most.

An original .50  gvt round drops right in (won't fit in my Shiloh), and the ammunition I load certainly seems like it is pretty loose in that chamber, but that bullet must bump up pretty well. I can shoot 20 rounds from that thing without any bore cleaning technique and honestly, the group size seems the same. The rounds still drop in the chamber without any effort. I don't know how far I could push that as I have never shot more than 20 at one time. They extract easily.

It is a great little gun, my only complaint is that it shoots 9 inches high on the lowest site setting and I have no desire to change its original architecture to bring it down.

For general information on U.S. military sights, most of these guns were sighted for 232-350 yds, depending on the cartridge, the firearm, etc.  The reason was to create the maximum "danger space" for shooting at infantry and/or cavalry.  As a result, most will shoot 15-18" high at 100 yds, depending on the cartridge.

So far as accuracy is concerned, you may want to try a hollow-base bullet with black powder.

I understand wanting to keep the carbine original.  But the Sharps generally had the front sight blade pinned to the base, and you can fairly easily temporarily replace the blade with a piece of brass or nickel-silver that is higher than the original.  The alternative is to tack up two bullseyes, one above the other, with the black touching.  Aim at the lower one and you'll probably be right on at 100 yds.