Designing the 2-diameter paper patch bullet.

[Distant Thunder]

This evening I am starting my initial load development for this 2D-PPB in my C. Sharps 1874 .45-70.

The first step is to determine how much powder (1 ½ Swiss) will fill the case to the very top when using my 14” long drop tube. That turns out to be 84.0 grains. If I want more I’ll will have to use a compression bushing and I will make one of those ASAP.

On top of the 84.0 grains of 1 ½ Swiss I started a .060” LDPE wad and then compressed that so it was .030” below the case. One thing which is causing me to have to seat so shallow is that my Starline brass is .020” short of the 2.100”. Surprisingly the bullet sits in the case not too bad. Care will have to be taken so it does not fall out while handling and chambering, but it is doable.

The start load looks like this:

521 grain 2D-PPB (Matt's)
.060 LDPE wad
84.0 grains 1 ½ Swiss
Federal 210 primer
Starline .45-70 brass
C.O.A.L. = 3.485”

A cartridge so loaded slides easily into the chamber until the last .020-.030” and the breech block cams it home from there.

These bullets are some of the very first ones I cast from this mold and are running 1 to 2 grains shy of those I cast once I figured out how this mold works best. These will do just fine for the first tests at 200 meters and I will cast some more as soon as I get time.

Shooting will be with a scope from the bench at 200M. I would hope to do a first test this coming weekend, if the weather will allow me to.

This is the same procedure I used with my .45-70 Hepburn and .40-65 C. Sharps 1875. After this first test and assuming something that looks like a group at 200M I will try a few different primers, though the 210s have always worked well in this rifle with Swiss and GG bullets so that is why I started there.

Tonight I'll load enough to get it zeroed and shoot a 10-shot group to see how it all looks. I pretty much expect this bullet to shoot pretty well out of the gate, but primer choice and powder charge can make significant differences.

Once I know what primer it wants I’ll go up with the powder charge one grain at a time to see if there is something it likes better.

It shouldn’t take very long to have a good load and then it would just need to be tested out to 1000 yards and that I would have to do at a match and hope for the best. I would likely try this bullet at a gong match Merrill out to 500 yards in May. The other possibility would be a paper match out to 600 yards at Wisconsin Rapids also some time in May. Shooting is very limited here in my corner of the world during the winter months.

If Matt’s bullet works as well as I think it will I’ll make a mold for myself with the same profile and OAL except the groove diameter base will be .040-.050” longer to allow for a bit deeper seating. I would ideally like to see .080-.090’ of the bullet is the case. I don’t, at this point, see any reason to change either diameter at all, the fit is about as good as it gets.