Captain*Kirk,
You have received a lot of good advice from other members. Probably a good idea to sort through it and follow what sounds right to you.
Just on this forum, there are several fellows who not only compete, but win long distance matches. There methods work and they can consistently proof it.
My method could easily be referred to, and maybe has been referred to, as slop bucket loading. I am not a competitor, merely someone who likes meat in the freezer.
I started out using SPG, a Lyman 400+ grain boolit, whatever brass and primer I had available and Goex black powder (usually ffg but sometimes fffg). I scooped enough powder into the case to allow a good bit of compression. I then made a measure to grab that amount from the bowl of powder I used. Using this measure I would scoop the powder and slowly pour it through a funnel into the primed case. The slow pour simulates the drop tube and allows the powder to pack into the case a bit more compact. If the powder was not compact enough I would use a wood dowel sized to be a slip fit in the case to compress it. Then seat the lubed bullet and call it good. Did I win competitions? Don’t know, never tried but at 100 yards the groups could be covered by my hand and more important, the meat ended up in the freezer.
So, now you have a couple of options.
Choose your poison!
Kevin
ps
The 45-70 is a good cartridge to learn with. Get Spence Wolf’s book. Some of the advice is dated and currently not in vogue, like enlarging primer holes and using magnum primers but it is a great basic manual.
http://www.4570book.info/#2896
Even when you tire of the 45-70 and move on to other bpcr, the knowledge you glean will work.
Kevin