I have shot several conicals but settled on this one...
502-500-SWC RG2 cavity HB, NOE Bullet Moulds
I hope that link works...
I shoot it with the hollow base without a wad.. (the wad may make a better seal but the skirt does a very good job of that and I notice no accuracy difference in my rifles). This mold is equipped to cast several different weights and bases... I have it set up to cast the largest bullet with the hollow base.
I've used the Lee 500 S&W mold as well, sized down to .498 and paper patched and it works as well... actually really well, but I hate the lee mold (i'm a mold snob I think) and I don't think a paper patch is necessary at these velocities. I've shot this bullet naked, sized to bore diameter with a good beeswax based lube and had excellent accuracy. This is a good bullet/mold combination to start with as the mold is inexpensive and you will have good success with it if your lead is soft and you size it correctly.
As far as accuracy.... With a scoped rifle... both the Ultralight and the Mountaineer... (I have both).. I consistently shoot 1 inch or a little less at 100yds. Not every shot.... I'm not a shooting machine... but consistently enough to know that these are accurate and I need to improve my bench techniques...lol. I get my best groups early in the shooting session... this is due to recoil not a dirty barrel or any other factors. The bullets need to be weight sorted too... I weigh to within 1 grain... and have great consistency. One grain isn't really necessary for hunting bullets but I do it anyway. If you don't weight sort, you will have fliers and problems in general. Your powder charge is important. I've found the best accuracy with relatively small powder charges.. 90-100 grains. I use real Black Powder... it's the most consistent... more than ANY substitute powder... including Blackhorn or 777... plus it's the easiest to ignite with a #11 cap. Pyrodex P is my second choice and it works very well as well. Charges are loaded by volume. The recoil in the Ultralight is heavy... at least to me it is... I compare it to a .300 ultramag un-braked shooting 200 grain bullets. The trigger guard hammers my finger if I hold the rifle softly... It's enough to rip my hand from the grip. The Mountianeer is no problem but your shoulder will get sore unless your young.
Sizing the bullets to the correct size is important as well. The Mountaineer has a tighter bore... .501... than the Ultralight... .502... at least in my rifles... I have found that if I use a very soft lead alloy I can shoot excellent groups with a very easy to load bullet sized .001 smaller than the bore diameter. I don't need to clean between each shot using Black Powder... but after 2 or 3shots... I am running a patch down the bore. In a hunting situation, the smaller diameter bullet goes down the bore just fine for a quick reload. At the bench, I'm cleaning between shots. Sizing to the actual bore diameter requires that you take your time loading the bullet... Its gotta go in strait or...problems will start to emerge. You can get better accuracy with a bore sized bullet, but for hunting, you don't need it.
This is fun stuff to me, but be patent and methodically test and refine your loads. It takes a little time to get all the pieces to fit together. When it does, the limit to your range will be your shooting ability and your sights. These bullets are hammers and retain enough momentum at 300 yds to kill anything we can hunt in N America. Think Buffalo hunting bullets... Buffalo Bill used a 42 caliber rifle (i'm pretty sure of that... maybe a .43? can't remember) that shot long heavy bullets... and he killed tens of thousands of buffalo with it working for the railroads. It works. Long, heavy bullets equal higher BC... which equals higher retained velocity which equals higher energy which equals deeper penetration. To me, the results and the confidence that brings is worth the extra effort. I'm not putting down sabots or anything like that, but Idaho doesn't allow sabots so I went this direction. You could use Maxiballs or the great plains bullets and they work too... but you do really gain a lot with the big heavies... plus your making them yourself... which is satisfying.
I just last week received a barrel from Knight that I ordered... it's a .45 with a 1/20 twist. I simply asked them if I could get the .45 barrel with that fast twist rate... They sent me one...wow... I'm impressed. It's made to shoot the long heavy Whitworth style bullets. There is a reason why the shooters of old used long heavy bullets for target and warfare... That rifle will be this winters project. For deer in Utah, with a turret adjustable scope and 500 grain bullets, 300 yards should be a chip shot.... If I can do it. And I can. I just hope my legs can keep up.