Hey guys, I'm not new to guns but I'm brand new to muzzleloaders. I just picked up a T/C .54cal Hawken and have no idea what I'm doing with it. The guy I bought it from said to use Triple 7 powder and sabot bullets and musket caps. So my question is, where do I start with figuring up a load for this thing? I'm going to go shoot it on Thursday and see what it can do.

When I was new, I went to my local gun club and got with the Blackpowder experts and had them go thru everything start to finish, including cleaning, loading and if there are issues, etc. It was a great learning experience.

The T/C's are rifled to use the Maxi-Ball type bullet. It will shoot patched round balls but not as accurately as Maxi-Balls.
Black Powder or any Black Powder Substitute will work.
I doubt it uses "Musket" caps. It probably uses standard #11 caps.Musket caps are quite large compared to standard caps.
The factory nipples wouldn't be for musket sized caps.
Clean the barrel thoroughly before shooting.
The T/C's are very nicely made guns. It will serve you well.
Good luck and post pics.

He said he had a modification done to the nipple so it can accept musket caps because they burn hotter. Do any of you have a recomendation as to where to start with a powder load?

Start with a powder charge of 60 grains and see how it groups, then increase the charge by 5 grains for each of the next groups. Somewhere you'll see what it likes.

http://www.tcarms.com/assets/manuals/current/Hawken_Manual.pdf

http://www.tcarms.com/assets/manuals/noncurrent/Shooting_TC_Side_Lock_Black_Powder_Guns.pdf

There is some load data way down the pages.

You will be well suited with 2ff black powder,patched round ball(.530) and #11 caps. If the weapon is stock it does not use musket caps. Clean with HOT soapy water, the heat will help dry the barrel and then oil well.

If the guy he bought t from used Triple 7 he may have installed a nipple that takes musket caps so he could set it off. I don't know if a #11 would ignite the substitutes reliably.

OP you would really be better off using real BP and a #11 cap. You will have to change the nipple.
Do a lot of reading on how to clean it. It isn't hard but you don't use the same stuff as on a smokeless rifle.

I bought a nipple that uses musket caps from Dixie gun Works about 15 years ago for my .54 Hawken.  So if the seller said musket caps, I’d start with those.  I use patched round balls instead of Sabot bullets or Maxi-Balls because I wanted to be traditional.  If I wanted to use one of those, I’d have bought a modern In-Line.  There is nothing wrong with that, just not for me.  I’ve brought down several deer with the patched round balls.

Congrats on the hawken .54, I have one as well and it rules!

The .54 cal maxi ball is no longer manufactured. I went through the last of mine last season.

Hornady does however make a similiar concept bullet... Great plain maybe... I forget. I hava a box. You have to pre lube them with bore butter... Unlike the maxi ball they do not come pre lubed...

Warning, the maxi ball type rounds kick like a fucking mule with 90gr's. Much harder than ball and patch

Unscrew the nipple and take it with you to the store to check fit.  T/C makes several nipples including musket nipples so be sure you get the right one.  I use Triple Seven occasionally and use a Hotshot nipple with #11 caps on my .50cal and I've only had two misfires- be sure to use fresh powder and caps for hunting though.  As mentioned, factory T/C Hawken barrels are not rifled for sabots, if you want to shoot them get a Green Mountain barrel or other brand with a faster twist.  One of the reasons folks use sabot rounds is that they don't know the actual bore of their rifle so it's hard to figure what size bullet or ball/patch combination you need- bore's can vary by manufacturer and the plastic sabot helps fill the bore, but the slower twist isn't optimal for it (ex. round ball barrels often run around 1:60" to 1:70").  A properly sized ball and patch combo will be surprisingly accurate.  

Thompson Center isn't making the .54 cal bullets right now but you can buy molds for them; casting is pretty easy, especially if you're only doing small quantities.  I melt lead outdoors on a Coleman stove then use a ladle to scoop and pour lead into the molds; there are several substances and ways to coat them.

In my experience, BP guns are more sensitive to powder weight than smokeless and each gun will have a favorite load that it'll be most accurate with.  As my gun is a .50cal my loading data would be worthless to you.  Contact T/C and they will get you an owner's manual with loading data!