Hello AkMike,

Well, I now know why African Hunters using Big Bore Double rifles, have Gun Bearers. WOW! My 20-577 Dixon Double really got heavy lugging it around. Unfortunately no luck bagging a deer with it. But I did enjoy using my 505 Gibbs for the task.

I've had a lot of emails asking why and how I'm using .510 - .511 bullets in my .505 Gibbs.

Here is a neat little trick. I start with some Cast Performance 350g gas check bullets. They run about $45 per 100. That's a heck of a lot cheaper than most bullets for the 505 Gibbs which retails for $1.50 to $2.00 each.

I use a .458 sizing die (with the decapping stem removed) to resize the body of the bullets. It actually "taper-sizes" them.

I made a small pusher plug that controls how far into the die the bullet is pushed. The deeper into the die you push the bullet, the smaller its gets. I only go to the depth of the top of the belt which is approximately .510" dia. on the gas check, smaller farther toward the point. I finger lube the bullets with ordinary sizing lube.

To remove the bullets from the die, I push them back out the bottom of the die with a small brass rod. since the die is tapered, a small tap frees them and they drop right out.

Here are the two brass rods. I used my lathe and made them a little fancier than actually required. The two bullets shown have been resized. Gas check is still .510 dia, but the band at the middle is .505 dia., with the front band a little smaller in dia.

The loaded cartridges have a good overall length and feed nicely through the action's magazine, even though these bullets have a pretty flat nose.

Since I'm only using 54g of IMR4198, there is a lot of air space in the case. I use a method from Smokeless for Black loading. I cut pieces of 5/8" dia. Foam Backing Rod (available at any hardware store) to lengths of 1.9" to fill the air gap and keep the powder against the F215 primer. Since the case mouth is only .505 dia. and the backing rod is .625 dia., I finger lube the outside of the foam rod ever-so-slightly and "screw" it into the case while gently compressing it with my fingers, being careful not to squeeze it too much or the cells of the foam will break and it won't spring back to full dia. The 1.9" long foam rod weighs only 1.9 grains. Its under slight compression and keeps the powder in place, even in those cases in the magazine which are subject to the rifle's recoil.

My chronographed muzzle velocity of 5 cartridges was 1680 fps, perfect for dangerous Wisconsin whitetail deer.