I'm getting ready to start reloading .45 LC for my Thunder Five. I was hoping to also find a way to make an analogue for the .45-70 which the gun is also able to fire (albeit with a different cylinder). Would I just find a loading with the same pressure or is there more to it? I have found one which uses the .460 S&W Magnum case and is in the same pressure neighborhood, will it work or am I just being dumb?

First welcome to the forum.

Second you have my old brain confused. The LC pressure is 14,000 the 45-70 is 28,000 and the 460 is 61,000. So are you wanting 28,000psi like the 45-70 without swapping the cylinder? I have no clue if the LC brass will handle the pressure. A shortened Casull would.

Assuming a LC case could ahandle the pressure I wouldn't load it to 28,000 by accident someone stick it in an old revolver and it could come apart.

Maybe others will understand but I'm having trouble.

Totally understand about being careful putting very hot loads in .45 LC's.

My plan was to use the .460 S&W Magnum case and load it with 9 gr of IMR Trail Boss and a 360 gr bullet, which yields 24,200 PSI according to Hodgdon's data. The Thunder Five's cylinder is long enough to chamber the .460.

What I really want to know is if I'm overlooking something in the way of safety.

Question that comes to mind is the 45-70 cylinder is designed for 28,000 is the LC? Will the larger rim of the 460 fit?

Larger rim is no problem, it's also chambered for .410 3" shotgun shells with an even larger rim.

I don't know about the strength of the cylinder, that would be something to verify before I try this.

Buy a 45-70 BFR.

If you want to increase your velocity with the 45 colt you could use the loads for the Ruger and Contender guns. They have pressures close to 24000 -25000.

The problem is, you have no way of knowing if your cylinder will withstand those pressures. You need to contact the gun manufacturer and ask them if the gun will survive with a steady diet of the higher pressure loads. If they say "NO" then it is likely that you will have to use the standard loads in the 45 Colt cylinder.

Thanks for the advice everyone.

I would contact the manufacturer, but they went under after the owner embezzled all the money. However, they did make sub-caliber inserts which allowed it to chamber .357's (35,000 PSI), so pressure *should* not be an issue.

But, with safety in mind I should have a certified gunsmith check it out before I try anything.

NO, if they made chamber inserts, it is the insert that is taking the pressure; not the cylinder, so don't interpolate any pressure data from that. If it is a 45-70 cylinder, do not exceed the SAAMI pressures for that round. 28kpsi. You can't duplicate 45-70 loads with a case as small as the 45 LC without exceeding it's pressure either. You are trying to defy physics. The real question is how strong is your LC cylinder. Rugers and colts are well known as to how much pressure they can take but this one?

Short cut? Go to the data manuals for .460 and find a load that equals the .45/70 performance you wish to duplicate. Obviously not the same case, so not likely the same powder or amount.

"Analogue for the .45/70?" -???- Huh?

O.K. many including Elmer Keith sought to enhance the power of the .45 Colt. He writes about it. He took a bullet, 300 grains, from .45/90 rifle and loaded it. Over loaded it. Had the bolt cut in the revolver cylinder expanding and sticking the cylinder... You are not the first... (This caused his switch to .44 Special. More nmetal in the "bolt cut.")

I suggest you first define .45/70. The original post civil war load was a 500 grain bullet with 70 grains of black powder. Velocity was in the 1200-1300 range. You want a 500 grain bullet out of a revolver? KICK! (I did not care for them out of my rifle...)

20th century the cases became solid head and will no longer hold 70 grains of powder with the 500 grain bullet. (The 405 grain bullet was a cavalary load that kicked less and no one wanted the 500 grain cartridges... Guess why?) You want a 405 grain bullet out of a revolver?

You mention pressure. Well. If you get the same pressure with the same bullet but less powder in a shorter barrel, NO this will not produce the same results.

Then there is twist. Rifle barrels are twisted for the longer bullets. Pistol barrels for shorter, lighter bullets. You get an unstable bullet and accuracy goes POOF!

Oh yes, the .45 Colt was also standardized for black powder pressures. 14K LUP. (Lead pressure units. CUP, copper units pressure.) Plus P loads might go 22K CUP. Now the .454 Casual or .460 Should be much stronger but also a different powder capacity. Putting a .45 Colt load into a .454 case is not recommended but a revolver for .454 should handle the possible over pressure of a .45 Colt load...

You can probably duplicate any safe .45/70 rifle load ***PREFORMANCE** with the smaller case at much higher pressure but probably a different powder. Once you have a load/case etc. that will push your bullet at approx. .45/70 level you seek, then downrange performance should be very similar.

It seems you are "on the right track." Shoot the gun with .45/70 (or not) and decide what you require for performance. A second cylinder with .460 cases should be able to duplicate this performance but with a different powder and probably a substantially higher pressure.

Hit the data manuals. What you desire is possible but a smaller case should require higher pressure. Luck. Happy Trails.

From the type of replies I'm getting, I think I should have defined my main object up front.

What I really want to do is for my gun to make the biggest BANG it safely can. I use the 45-70 as my example because it could fire these if I were to swap out the cylinder out for one which will be expensive and hard to find.

So ... perhaps I should have phrased the question more like this: If I want to push the envelope of power and noise, what sort of factors should I take into account when selecting a load?

First of all find someone with a .454 Casul and touch off a few rounds.
Then you will find some other project that is both more fun and rewarding.

quote:

Originally posted by Cowboy_Dan:
From the type of replies I'm getting, I think I should have defined my main object up front.

What I really want to do is for my gun to make the biggest BANG it safely can. I use the 45-70 as my example because it could fire these if I were to swap out the cylinder out for one which will be expensive and hard to find.

So ... perhaps I should have phrased the question more like this: If I want to push the envelope of power and noise, what sort of factors should I take into account when selecting a load?

you have to take the guns ability to handle pressure into account.
there is a reason why they have different load levels in the books.
the brass will handle all of them.
a colt will not handle ruger only loads.
a Dan Wesson will.
your's may or may not.
same as 45/70 loads.
trapdoor loads and ruger #1 loads are different pressure levels.

if you don't know you have to assume the gun is built to the lowest level.
or you can eat top strap, finding out otherwise.

Cowboy Dan,
You do seem to be missing something.
Any load beyond the listed maximum load in the reloading books can be injurious or even life threatening. Your revolver, as I understand it is made to hold 45 Colt in its present configuration. You do not have the cylinder that holds 45-70 rounds for your gun as I understand your posts. You have no idea if the cylinder is designed to handle anything more than standard 45 Colt pressures.

Under those conditions you should not attempt any loads that are not listed for standard 45 Colt ammunition. Using the "+P" rounds in your gun may split the cylinder and cause the same kind of damage to you and those nearby as a grenade might.

If you want more power then get a gun that is designed for that power level. There is no reason to endager yourself and others for a lack of knowledge on your part.

First, I have never heard of a thunder five. A five shot revolver?

Second, what is the bore diameter? You cannot fire a 45/70 round in a barrel made to shoot a 45 colt. The colt would need a .452 bore, the 45/70 would use a .458 diameter barrel.

There is NO combination barrel size that will shoot both cartridges accurately. If the barrel IS .458, the smaller colt bullets would rattle down that bigger barrel like a pea in a gallon milk jug.

On the other hand, firing a 45/70 round in a .452 barrel would raise pressure through the roof. That .458 bullet would have to be squeezed down .006 as it enters the smaller bore, spiking pressure.

Dan, you're treading on thin ice here. Forget the hollywood flame thrower guns, they don't even take a real cartridge. The true joy of shooting is to make good reloads for less money than factory, that shoot tiny groups. Forget the noise, it's a by-product of shooting, not the goal!