As long as you are using Black Powder under a conical bullet, I cannot imagine any way you can load your carbine in excess of 1400 fps. Head down to the Spencer page, there is an excellent 350 grain mold down there, as well as the Rapine, and others.
It is a CAS style match, though with only 2 guns, a rifle and pistol. Expect multiple reloads. If you want to use a percussion gun, best to have extra revolvers or cylinders that can be precharged and capped on the clock for reloads. You can of course, simply shoot your Remington and take the misses for the reloads if you wish/if thats what you have. We're here to have fun.
Please review both the Battle Rifle entry, as well as the registration entry at the top of this page. I hope to see you there. Drydock.
Please understand and make it clear to your friends: this is not reinacting, but a get together of like minded individuals to enjoy the weapons and acoutrrements of the Victorian era, in a multigun combat style match. We'll have folks period correct down to the stitchs in their long johns, and we'll have folks uniformed by John Ford, and folks who ain't quite sure what all this is, but they'd like to try it. All are welcome.