Designing the 2-diameter paper patch bullet.

[Distant Thunder]

The rifle I am designing a 2-diameter paper patched bullet for is a Pedersoli Sharps that has been rechambered to .45-100. I don't have the rifle, which would be ideal, so I have to rely on the owner, Matt, for the information I'll need to get this done.

The things I need to know are, the bore diameter (.450"), the groove diameter (.458"), the mouth ID of a fire formed case (.460"), The bullets seating depth (.100"), The length of the throat (.125"+), and the amount the paper will add to the cast diameters (.007").

The bore and groove diameters I got from Matt. The case ID I measured from a case Matt supplied using a gage pin. For the bullet seating depth we agreed we would shoot (pun) for .100". The length of the throat (.125") I got from a chamber cast that Matt supplied. I would rather get this from the rifle by measuring to the base of a .459" diameter bullet resting against the lead angle, but I'll make do with what I have. The most that could go wrong is that the seating depth would be a little more or less, not the end of the world. For the amount the paper will add to the bullet diameter Matt sent me a patched bullet that he has been using in the rifle and I removed the patch and wrapped it around a .444" gage pin and measured the final diameter.

Matt said he has been shooting a .433" diameter BACO elliptical bullet and he has been trying to get it to shoot well for over two years. So we will see what happens with a 2-diameter bullet of my design.

When I say a bullet of my design please understand it's nothing special and I'm sure there are other bullets out there that are very similar. This design has shot very well for me in the long-range matches held at Lodi, WI. I have used this bore diameter bullet from a mold I made in 2009 to win 5 times and place in the top 5 13 other times. So the bullet does shoot well in both the rifles I've used it in over the past 9 years. The only difference will be that this new bullet will have a base diameter that will patch to groove plus .001" (.459").

When I used my bullet in my Shiloh .45-90 I had to taper crimp my cases quite a bit to hold the bullets in the cases. Using a 2-diameter version Matt will only need a very light taper crimp to hold the bullets in, if that.

In shooting a 2-diameter ppb in my .40-65 since last year I have come believe there may be an advantage to having a ppb that sets up against the lead angle when chambered. The accuracy that I'm getting from my .40 is amazing, the best I've had with ppb. I think having that little bit of initial resistance as the primer detonates and the powder ignites may be a good thing. I know that with my bore diameter bullet in my .45-70 just the primer alone is enough to move the bullet about 6 inches into the barrel. Don't ask how I know that, I just do.

The following a 3-D model of the proposed long-range ppb that Matt will be working with. It starts with an elliptical nose profile, but I modified it with a nose radius that is 28% of caliber because I don't believe overly pointed bullets are best in the transonic zone that we must work within when shooting BPCR. Most any load that can be safely fired with black powder will start out between 1200 and 1400 fps and all will drop below 1000 fps very quickly, usually within 400 yards. So it is with black powder and lead. I do like to keep the nose nearly half the overall length. This design has been very accurate for me and has proven to hold up well when things get twitchy and others are struggling to hold on to the target. I like this bullet! The overall length will be 1.440" which I find is very stable in an 18-twist rifle.

   

Now the real work begins!

DT