Re: Taurus Thunderbolt 45LC pump rifle???
I just reviewed my 2005 USFA catalog for the Lightning and I saw no mention of only using black powder in this rifle (???). Where did you see this limitation?
The three cartridges listed are 45LC, 38WCF (commonly know as 38-40), 44WCF (commonly known as 44-40). All are readily available as loose brass cases and in commercial ammo. These were invented during the period before smokeless powder was available and at that time were loded with black powder. Of course today only smokeless powder loads are commercially available and in those calibers the loads are designed so as not to damage guns from the black powder era. Not only are black powder pressure characteristics different from smokeless powder but the metalugy of that time greatly lagged todays available metals. Winchester answer to the metal's strength was the use of Nickel-Steel in the barrels which allowed smokeless powder usage without concern. Today all guns except the "black powder muzzle loaders" are made of materials that are more than strong enough to accommodate commercial ammo in those calibers.
You really don't want to get into black powder loading of cartridges (sorry, you black powder loaders but this is my opinion). Black powder shoots messy leaving a black soot in the barrel that requires frequent cleaning to just fire the next set of shots. Add to that special reloading tools to assure being able to completely fill the case and pack the black powder correctly. After a range session you must clean the rifle that day as the soot left by the black powder is anhydrous (attracks moisture) and the barrel and any metal under the soot in the receiver will rust quickly. Normal cleaning solutions do not work as well as soap and water, which if not thoroughly dryed out will also rust the gun.
Add to that the dangers of black powder: it is an explosive while smokeless powder is a propellant. Set a pile of black powder off with a match (virtually, not actually unless you know what you are doing) and it goes up in an instant flash. Do the same with smokeless powder and it burns slowly. As an explosive, black powder is suppose to be stored with special rules as to how and in what quantities. Few gun stores sell it because of its explosive nature. You could choose black powder replicas like Hodgedon's Pyrodex. (The inventer of Pyrodex was killed in a Pyrodex powder explosion at his factory--really safe stuff!)
The USFA Lightning, I am sure, is made from modern metals and as such will shoot commercial smokeless powder ammo. The available loaded ammo is loaded to pretty safe levels, well below the ability of this gun and even period black powder guns to handle it. Most firearms manufacture shun reloaded cartridges of any type (smokeless or black powder) and most state that their warrantee is void if reloads are used in the gun. This is because with reloads they have no idea to what level they have been reloaded: a small overload can hurt the gun seriously.
I have a Remington black powder revolver that I built up from a kit. It turned out beautiful but I rarely shoot it as even Pyrodex is extremely messy and the gun is time consuming to reload for each cylinder full. It sits on the shelf and gets taken out only once every five years or so for those reasons. Black powder (Pyrodex, too) sucks!
Hope this helps.