I obviously haven't shot every muzzleloader combination on the market, so I can't actually say that this is the most accurate muzzleloader combination available. I don't think anyone can say that. However, after shooting this combination of muzzleloader, ammo and propellant; I can say that it is extremely accurate and easy to use.
Muzzleloader: CVA Accura V2 209 Magnum Break-Action Muzzleloader. The CVA V2 Accura model I tested (and now own) was CVA model #PR3116SM. There are numerous CVA V2 Accura models out there, but I choose this one particular Accura model because it came with a one-piece scope mount and just overall looked really cool. Any of the CVA V2 Accura models will work fine, just choose the one that matches your taste and budget. This model happens to be one of their more expensive models.
The "V2" just stands for "Version 2".
I really liked how easy the breech plug was to remove. I've owned other muzzleloaders and always had a problem getting the breech plug off to clean. On my previous muzzleloader, I actually had to resort to a socket to get the breech plug off occasionally. The CVA V2 Accura has a twist-off breech plug that does not require any special tools, even after multiple shots and fouling. It was super simple to remove.
I also really liked the break open action that is built right into the thumb guard. This made opening it very easy.
I use a .50 caliber bore snake to clean the barrel after every 3rd shot when sighting-in. Then, when I get home I use the cleaner and pads to make sure the breech plug and barrel are super clean.
Overall, this muzzleloader was very easy to operate, keep clean and most importantly had great accuracy.
Black Powder: 110 grains of Blackhorn 209 Powder. Loose powder is much more accurate and consistent than pellets in my opinion. I have shot both and the Blackhorn 209 powder and pellets. Pellets gave me inconsistent shots. Blackhorn 209 is far more consistent for me. I know the pellets are easier to drop down the barrel, but you can measure out the loose powder ahead of time and it really doesn't take that much longer to just pour it down your barrel. I use plastic measuring tubes made just for Blackhorn 209 (mentioned further down). Most people are only going to get one shot, so why not spend an extra 30 seconds with Blackhorn 209 and make your shot count. Avoid the pellets and use loose powder or Blackhorn 209! After I pour it down my barrel, I'll drop my ram rod on it a few times to make sure it is packed together. Do it until you feel your ram rod bounce just a bit.
Change Out Factory Breech Plug: If you are going to be using Blackhorn 209 powder with the CVA V2 Accura, be sure to spend a little extra and get a breech plug made just for this combination. The breech plug is CVA model #AC1611BH. It is made specifically for using Blackhorn 209 powder with the CVA V2 Accura.
Ammo: Barnes Spit-Fire T-EZ 250 grain bullets, model #30587. Only reason I use this round is because I had a friend of mine mention ow accurate they were for him. I've been shooting them ever since.
Measuring Tubes: Blackhorn 209 Muzzleloading Powder Tubes. Allows you to easily measure out your Blackhorn 209 powder and pour down your barrel.
Funnel: I bought a small funnel to pour the Blackhorn 209 into my measuring tubes. You can also use the funnel to pour the powder into the top of your barrel. It makes it so you don't spill your powder everywhere. The funnels cost around $1.00 at any auto parts store or Wally World.
Scope: Bushnell Trophy XLT Riflescope 3-9x40mm DOA 250, model #733960BP. This scope is not very expensive (less than $200) and is very crisp and clear given its low price. It has a BDC reticle. I zeroed mine in at 100 yards and used the scope's reference points (lines below the crosshair) to go out to 300 yards.
Primers: Winchester's Triple Seven 209 Primers. Some people may disagree with me here, but I'm not too concerned with the brand of 209 primers as long as they work every time I pull the trigger. There purpose is to ignite the propellant. As long as they do that consistently, you'll be fine. I use Winchester's Triple Seven 209 Primers.
Well there you have it. With this combination, you should be on your way to taking your next large game animal with accuracy and ease-of-use during muzzleloading season. Have fun hunting!