Pretty Sure My Sharps Isn't a 45-120

[country gent]

I believe the 45-90 case is 2.4"long not the 2.1 of the 45-70. also check your twist rate. A lot if the reproductions were 18 twist good for 500 grn. Some are 1-16 and will handle even longer bullets.

I have a C Sharps hepburn in 45-90 with 2.4 inch starline brass I get around 82 grns under a 550 grn bullet. Nw manufactured brass sis solid head and thicker than the older id meaning less powder capacity.

[Gunlaker]

I'd still do a chamber cast. There could be any sort of custom chamber on that rifle. A good chamber casting will tell you not only what cartridge the rifle is chambered for, it'll also give you some clues as to what bullet it'll shoot well. You can easily get freebore diameter & length plus leade angle. The chamber casting is going to be a lot cheaper than buying several molds. Plus you can re-melt the chamber casting and reuse it for another rifle at any time so it's nearly free. Before I did my first casting I was resistant to doing one but then I found out how easy it is and how useful it is. I've done more than a dozen of them since starting.

Chris.

[harringtondav]

Thanks, and dang. My brass measures 2.1".
But all is not lost. I have enough 45-70's and 45-120's to swap for 2.4" brass.
The copper mold below was my Pop's. .441" dia, 1.5" long, 525 gr. ...thinking paper patch (?).
So it looks like I may be able to recreate your recipe. I believe my barrel is original, but I don't know the twist. 16# rifle with a heavy octagonal barrel.
Thanks again.

[Don McDowell]

The 45-70 cases won’t stretch
The worst that can happen is you’ll lead the heck out of the barrel or possibly ring the chamber if you fire enough rounds

[Huvius]

I'll about bet it has been chambered for the 3 1/4 case at one time, but it was with the tight paper patch chamber. Any bullet over .450-454 diameter isn't going to chamber. Unless it's one of the really short 300 gr express bullets.
You might see if you can get ahold of some .444 slicks and wrap them in 8 lb paper, if you don't have his mold. Over 120'ish grains of 1f powder a .060 fiber wad, a 1/16 grease cookie and a thin wad punched from wax paper or a playing card.
Neat old rifle to be sure.

THIS^^^

Your mold will patch up to .449-.450" and likely slip nicely into the bore while your 120 case sits nicely in the chamber - just as it was intended.

I'll throw my hat in for a chamber cast as well. I wouldn't mess around with any other paths until you do that and know for sure what the chambering is.

[Bent Ramrod]

Looks like you have a Yankee Specialty Co mould for a .45 paper patch slug. Four wraps of 0.002” thick tracing or vellum paper should bring the diameter up to 0.449” or so for a slip fit into the bore.

Any chance the barrel is chambered for the original Sharps 2-7/8” case? That was sometimes referred to in the old days as “.45-120” because with sufficient compression, 120 gr of powder could be stuffed into the case with a card wad and a bore diameter paper patch boolit barely seated into the case mouth. The normal loading was 110 gr or so, however.

Winchester treated the 2.4” case as an Express round, with a slow rifling twist to shoot short 300 gr boolits for a flatter trajectory at the typical 125-yd+/- blackpowder hunting ranges, calling it the “.45-90 WCF.” Sharps made their rifling twist quicker for this case to suit a longer boolit in the 425-500 gr weight for better stability and penetration at long ranges, and kept the shell length description. Up to 100 gr or so of powder could be put into this length case.

I would go along with the general recommendation for a chamber cast. Given the scarcity of long .45 cases nowadays, a couple ounces of Cerrosafe (which can be melted out of the chamber if the casting sticks along the learning curve, and can be recast over and over and saved for the future) is a cost effective alternate to possibly messing up cases in trying to figure out what you have.

[harringtondav]

Yes. I stopped beating around the bush and just now ordered Cerrosafe. BTW Bolton Metal products was 1/2 the cost of Brummels.
After I get a good casting I'll know for sure the chamber dims. I wasn't aware that a 2-7/8" existed. I'll report back with the dimensions
I have (20) 3-1/4" cases that are basically boat anchors, so I can cut them down to match what I find in the casting.

I plan on getting 1" or so of rifling so I know true bore size.
This gun has five groove rifling. Not the easiest to measure dead nuts accurate. Is there a stickey on the forum that explains how to measure bore size with an odd number of grooves?

[harringtondav]

..bad post. ...meant to quote another.

[harringtondav]

Yes a flannel cleaning patch and a Colton ball about an inch into the rifling will work
Kenny and Mine Ray have both given some good suggestions to look at doing before the chamber cast
But with no chamber or caliber markings on the barrel a good chamber cast will answer a lot of questions
Is that an original rifle or something your dad rebarreled?

I'll be pouring a chamber casting once the Cerrosafe comes.
I want to follow up on your ref to Kenny and Mine Ray before I try this. ....who are they, and how do I find their writings?
Thanks.

[John in PA]

When you get around to doing the chamber cast, use Duxseal or modeling clay to create a dam around anything you don't want metal to flow into. Once it solidifies in your extractor groove or lever spring mortise, it could be a bugger to get out. When in doubt, dam it! A small empty soup can with a spout bent into the lip works just fine to melt in and to pour.

[Gunlaker]

One other suggestion for pouring cerrosafe is to take a coke can and cut it in half. Bend it to make a pouring spout. I preheat the barrel around the chamber until it is hot to the touch with a heat gun. I also use the heat gun to melt the cerrosafe in the coke can. I plug the barrel with a few patches maybe 1" ahead of the chamber end.

Also, the stuff solidifies pretty fast and then starts expanding a little as it does. I'd advise not listening to the instructions and us a cleaning rod to knock the casting out maybe 30-60 seconds after it's solid.

There are formulas to convert cerrosafe casting dimensions to actual dimensions based on the casting age.

Chris.

[harringtondav]

When you get around to doing the chamber cast, use Duxseal or modeling clay to create a dam around anything you don't want metal to flow into. Once it solidifies in your extractor groove or lever spring mortise, it could be a bugger to get out. When in doubt, dam it! A small empty soup can with a spout bent into the lip works just fine to melt in and to pour.

Thanks, I made the chamber cast shown below using your method....almost. I forgot to dam the extractor. But with an O ring pick and a little direct heat gun directly on the extractor I got it cleaned out.

I sanded a 1/2" fluted dowel down until it was tap snug in the rifling at the end of the chamber. This worked well.

I've cut a 3.25" case down to the 45-110 2.875" length, loose fit the original bullet to the 3.36" spec OAL.

This leaves me with another question: The bullet will now have a .300" 'jump' to contact the rifling. Is this OK?

Pic shows an original 45-120, the chamber cast, and a 45-70 Govt for reference.

[harringtondav]

When you get around to doing the chamber cast, use Duxseal or modeling clay to create a dam around anything you don't want metal to flow into. Once it solidifies in your extractor groove or lever spring mortise, it could be a bugger to get out. When in doubt, dam it! A small empty soup can with a spout bent into the lip works just fine to melt in and to pour.

Thanks, I made the chamber cast shown below using your method....almost. I forgot to dam the extractor. But with an O ring pick and a little direct heat gun directly on the extractor I got it cleaned out.

I sanded a 1/2" fluted dowel down until it was tap snug in the rifling at the end of the chamber. This worked well.

I've cut a 3.25" case down to the 45-110 2.875" length, loose fit the original bullet to the 3.36" spec OAL.

This leaves me with another question: The bullet will now have a .300" 'jump' to contact the rifling. Is this OK?

Pic shows an original 45-120, the chamber cast, and a 45-70 Govt for reference.

[kootne]

Those old chambers were not cut the same as what we consider "best practice" 150 years on. Here is a photo, cast from a Sharps 1874 Factory conversion from a percussion carbine to a "Business Model" configuration. I have seen similar chambers in 1878 Model 45/70's. The chamber cast is marked with a scribe mark on the red felt tip marker spot. The scribe mark is 2.03 from the front of the rim to show where a 2.1" case would be in the chamber. It is .325 to the beginning of rifling from that scribe mark. This chamber would freely accept a case of 2.3" long based on measurements of this casting
.

[elmacgyver0]

If you are using powder coated bullets and they are bore riders, that could be the issue.
I have this problem with my .45-70s.

[harringtondav]

If you are using powder coated bullets and they are bore riders, that could be the issue.
I have this problem with my .45-70s.

My guess these are powder coated, or some other lube coating. Chey-Cast 300 gr.
Not sure what you mean with a bore rider bullet. .457" dia. You can see the rifling bite marks on the nose.
When seated to length the same amount of bullet exposure as with the 45-120 loads. Approx .4" of a .76" bullet.

I've read bullet jump affects accuracy in smokeless rifles. I'm not too worried about this, but I am worried about safety and excess leading.
Do you think the .3" jump will be OK?

[craneman]

Looking at your photo I'm not sure you cast the entire chamber. I like to have at least a 1/2"-3/4" of rifling on my casts to be sure I have a complete picture of the end of the chamber and leede. If you are short of the end you still won't quite know what you have or what bullet might work best in your rifle as you want a bullet that fits a fired case mouth and the throat-leede.
Todd