45-120 -versatility ?

[ascast]

Hope this category is best. Got into a discussion about the 45-120. Question is can you use it as a 45-70? just seat bullets way out ?
It looks like the base dia. would be OK. Or maybe a 45-90? It is not a popular cartridge and brass is way too expensive.
so school me up
thanks

[beshears]

I would expect the bullet to bump to 50 cal in front of case then be squeezed back down to 45 cal at throat. I would expect terrible leading and no accuracy. Find a few cases and reload case at bench. Reprime, powder and wad and seat bullet by hand in the case.

[NSB]

I’m confused by your question. 45-120 brass is longer than 45-70, so it won’t fit a 45-70 chamber. Seating the bullets “way out” would only make the round longer yet. I have seen the question asked, “can I shoot 45-70 in a 45-90 or 45-120 gun” and the answer is yes, but the jump to the lands may affect accuracy. The 45-70, 45-90, and the 45-120 are basically the same case but in varying lengths. Using black powder requires a lot more powder than smokeless does to achieve even closely the same velocities so the cases are longer. A 45-70 chamber with smokeless powder will easily surpass the velocity of black powder in a 45-90 or 45-120 chamber with black powder.

[Don McDowell]

The 120 case is an inch and a half longer than the 45-70 case. The bullet would expand to chamber diameter and then be swaged back to bore/groove diameter, leading would be ferocious the velocity would likely be miserable, and accuracy most likely nonexistent. This isn't a 38/357 thing.If you have a 120 either spend the money for proper cases or have it rebarreled.

[greyhawk]

The 120 case is an inch and a half longer than the 45-70 case. The bullet would expand to chamber diameter and then be swaged back to bore/groove diameter, leading would be ferocious the velocity would likely be miserable, and accuracy most likely nonexistent. This isn't a 38/357 thing.If you have a 120 either spend the money for proper cases or have it rebarreled.

Don is it possible to set the barrel back/ shorten the chamber ? or are the action threads too big for that manouver ?

[Mr.doug]

Don’t know the action but if is a straight barrel and no tulip like a Shiloh it could be set back
Re-threaded and rechamberd. The hanger for the forend will also have to be moved

[country gent]

Setting the barrel back would require recutting the chamber rim and extractor. While the45-120 and 45-70 are considered straight walled there is a slight taper to them. The other is getting the reamer pilot into the bore solid enough wen starting out. The 45-70 reamer may start to cut lightly before the pilot engages the bore. In a lathe with a good float this may not be a problem by hand it may cause some problems

[Don McDowell]

Don is it possible to set the barrel back/ shorten the chamber ? or are the action threads too big for that manouver ?

As Mr Doug and country gent have stated it would be possible, but depending on the type of barrel. It would also be a better outcome if a chamber cast was made and then a proper reamer made and someone really good at lathe set up. It would be something needing to be done by a gunsmith and not a gun parts exchanger.
In the end a rebarrel would be the better option, IF you don't want to buy the proper cases in the first place.

[Mr.doug]

I agree with don it would be better to rebarrel it especially if it’s 30” long. Save the old barrel
2 barrel set or may be able to less it off later . Or sell the gun and get a cartridge u prefer to shoot.
Just my 2 cents.