One reason was the current wisdom that these old rifles shouldn't be subjected to smokeless loads, something I'm not sure I totally agree with, however comtemporary pressure levels should be respected.
The second, and main, reason was as with all my military rifles I wanted to get a "military type" load to get the feel for how a late 19th Century user of a Buffington sighted model 1884 would have experienced his Trapdoor shooting.
I my researches both on and of the net there seemed to be two schools of thought, one was the current what I called the Buffalo hunters school of BPCR reloading for silouette and scheutzen shooting. Using the experimentation and the techniques of benchrest, allbeit adapted for BP. This school mainly uses Sharps rifle copies such as Pedersoli and Shiloh and has been recently prosletyzed by Mike Venturino in his books and articles on BPCR shooting.
This method has its attractions from a tinkering point of view but I just felt that this wasn't necessarily going to get me the results I was after in a comtemporary 1888 rifle barrel which miked out at bore .458" and groove .460", difficult for me to measure accurately being a three groove barrel. All these repros seem to be made with tighter tolerances with the Pederosoli's having progressive rifling.
Being a dedicated .303" shooter I was always impressed with how the cartridge and rifle worked together so well 2-4" groups being accepted as the norm with any rifle using any ammo and in most cases doing nearer 2" than 4". I reasoned that the Trapdoor, having a reputation for accuracy, should be the same and with millions of rounds of Government 45-70 being produced they must have got the loading off to a Tee.
So how did they do it was my question? well guess what I wasn't the only person to ask this question and early on in my work I came a cross a book by JS and Pat Wolf which describes just what I was after how to load 45-70 BP cartridges to original specifications.
This is an excellent home produced publiction that describes one chaps obsession with getting the Government load, JS Wolfs proceedure is what I've based my early forays into reloading for my Trapdoor on.
To date I've loaded and fired 200 rounds.
The first 100 were experimental using two types of Balck Powder, Swiss No4 (1 1/2FG) and TPPH and two bullets both based on the original bullets used in the Trapdoor. They were thrown from a Lee 405gn hollow base mould and a SAECO 510gn Postell mould using a soft 30-1 lead/tin mix.
The first 50 rounds were loaded to the Buffalo gun school with wads and various compression and seating depths, these were a total failure in my Trapdoor and a bit disheartening to say the least, however the next batch of 50 made as per Wolf showing promise at 30 yrds with one load coming in at just over the inch.
I've now tried some at 100-300 yrds and had a couple of loads hold 4MOA at each distance which looks promising. I shot these yesterday in sub zero temperturtes, the paste was freezing in the butts so the patches wouldn't stick and there was strong northerly wind so not ideal testing conditions although the conditions were testing.
Overall the rifle seems to prefer the heavier bullet with TPPH powder, the best groups with the lighter bullet were shot using the Swiss powder.
Interesting the groups seemed to settle down the farther back I went.
The 405gn bullet is thrown from a Lee mould, I have to confess I don't really get on well with Lee moulds and find them a lot harder to use than iron moulds regardless of what Lee say on their packaging. Although the bullets were weighted to within 1gn the finish of the Lee bullets still left a lot to be desired to my eye so a similar design from NEI is on the cards for the new year.
I've had a lot of fun with this rifle and feel that a load that will be good enough to compete in the Trafalgar with is not far away, so here's some photo's of the process.
Case preperation consisted on drilling out the flash hole and squaring the case mouth. The case mouth was expanded with an "M" type expander die to 458"/459". The "M" type die with its stepped expander is crucial to seating the bullet square and avoiding lead shaving during the seating process.
The 45-70 is a compressed load and as such the powder column needs to be broken up a bit to get instantaneous ignition of the powder before the bullet starts moving to far up the barrel. Black powder being an explosive is different from smokeless powder in its behaviour but with compressed loads you can still get a progressive burn/ignition, hence the need for an enlarged flash hole and the use of Federal 215 Magnum primers as they seem to have the longest burn of the brands.
Drilling out the Flash hole with a #41 drill bit to
.096".
The base of the case was also countersunk at the same time to mark the cases as having enlarged flash holes. I also deburred and uninformed the enlarged flash holes at this point with RCBS hand tool.
Trimming the cases, the actual length isn't that important so long as they are all the same length and have the mouths squared for an even crimp, case length is supposed to be 2.105", all my new Winchester cases were less than this with off square mouths so trimming was a must.
Federal 215 Large Rifle Magnum primers.
Repro of the contemporary Pope capper/decapper, main use is to decap the cases on the range before they get tossed into a bucket of water. However in the spirit of the original I use it to prime the cases as well.
Powder charging was next, on the left is my home made drop tube a la Buffalo style loading and on the right is the Lyman BP measure and drop tube.
Trickling the powder down the home made tube really settles the powder in the case requiring less compression, just dumping it from the Lyman measure down its drop tube almost fills the case requiring more compression, the latter seems to work best.
Compressing the powder with a compression die is next, this has to be done so that when the bullet is seated it just sits on the powder, air gaps are supposed to be avoided in the interest of safety. If you use the bullet to compress the powder then the bullet will deform as it takes a bit of effort to compress the charge. The Rockchucker makes light work of it.
Here the first 11 cases are compressed the next 10 are charged but not compressed, you can see how far into the case the powder must be compressed.
Case going into the compression die
And coming out, powder compressed
Bullet seating next, Lee 405 grainers on the left SAECO Postells on the right. 30-1 lead tin mix. TPPH Black Pwder can be seen in background on the left.
Bullet seating, Lee 405 grainer first
The big postells get done next, now there's a sexy bullet
All thats left to do now is give them a run through the crimp die, write up the data log, box and notate the ammo then off to the range to make some smoke