Idaho:
Ok, after reviewing your post you say you are shooting the 51-450M. In looking at the specs I see the bands bottom to top 504, 504, 506, 507. Is it hard to start this bullet? I know this is a tight fit in a Hawken. Why tapered? Why not a straight. 502 or 503 or 504? Reason I ask is on my cast bullets mine are .504 and I been sizing down to 502. They still fit semi tight but a little easier to load in my Hawken.
VERY Good point! And glad you asked, The reason i had this Mold, and at least 2 others Made Oversize is i was using Pure Soft Plumbers lead at the time, and thought i needed to use Pure lead in Muzzleloaders? When using pure soft lead the Bullets would start to “Give Up” about Halfway down the Bore When Loading, and by the Time they reached the Powder Charge they were Loose, Loose Enough that i did NOT trust them to stay put on the Powder, i feared a Bullet slipping off the Charge in a Hunting situation, pulling up and taking a Shot, And VERY possibly “Ringing” My barrel.
But even after having these Molds cut this LARGE oversize the problem stil occured When Loading Pure Soft Lead?? It was after this that i came up with the idea of going to 1-40 Alloy, i picked up a 9 pound Chop Block of it, After pouring these bullets of this 1-40 Alloy they Held the Bore like a ROCK!! In fact they were on the TIGHT side to load! But i knew i had found a Cure to “Loosening bullets” When Loading. I then started working on Custom Sizer dies for each of my Guns, For example my .50 Cal LRH has a .501 Bore, For hunting i size my bullets to .502, they Start good n tight, but i can push them in with my Thumb, They Stay good and tight all the way Down! Same thing with my 45s and 54s, I Customized Sizers for Target use, and Hunting use. For target use in a controlled environment (Shooting Bench) i prefer my bullets to “Bore Ride” so in my .50 Cal with .501 Bore, i size my bullets to .500, This way they just “Kiss” the Rifling on the Way down. But for hunting i want a Good tight fitting bullet that will NOT budge off the Powder Charge unless i ask it to! (Pull the trigger)
In conclusion, If i had known then what I know now (1-40 Alloy) i would NOT have had these Few molds cut this Large oversize, there was simply no need. For my .50 I would have went .503 all Bands, This would have made the Sizing a bit easier. Though I don’t have any problems Sizing these oversize bullets as it is, I lube them well and they Slide right through no problem! I have several rifles of all Calibers, and each has it’s own unique Sizing needs, the Largest 50 Bore i work with is .503, i run my bullets through a .504 For this Rifle. If you are only working with 1, or 2 Rifles this makes it much easier, if you know the Bore diameters (Say .501, and .502) you would be PERFECT with a Mold Cut to drop bullets at .503-.504 then Lube and push them through a .502-.503 Sizer
Hope this clears this up, and makes sense. Pure lead was my Problem from the Very beginning! After switching to 1-40 Alloy I solved the “Loosening” problem, But i had already had 3 oversize Band Molds Made. After going to 1-40 Alloy I have not looked back at pure lead again, in fact I don’t want any of it! Look at our World Class BPCR shooters, The VERY LARGE majority of them use at least 1-30, With 1-20 and 1-16 Alloys being the most popular. If pure lead was so great, Those guy’s would DEFINITELY be using it! But fact is they are NOT, and these guy’s compete to 1,000 Yards. Accuracy is EVERYTHING to them!! And they get just that with the Harder Alloys
) But these Treso’s would require Drilling out to .033 in order to get Reliable ignition, One must be REALLY Careful here and NOT open them up to much or you create a Dangerous situation! As long as you understand the Requirements of Triple 7 I believe accuracy is there, But again i have only shot it 1 time. 
