I earlier said that alot of powerful, effective deer killing loads could be operated under 10,000 psi. As a starting point, I would like to explain why and how that is possible, because for many, it may seem to be very anemic pressure for a hunting rifle. Lets consider a centerfire rifle first, say a 25-06. Loads for the 25-06 need to operate at peak pressures less than 51,000 psi and for 100 grain bullet, the muzzle energy is in the neighborhood of 2300 ft.lbs. Now the pressure impresses force on the bullet by the following equation

Force = Pressure (lb/sq in.) * Area of bore (sq. in.)

So at peak pressure, the force is:

Force = 51000 * (PI*.25^2)/4 = 2503 lbs. force

Now lets calculate the pressure required to generate the same force in .50 caliber. The big difference in pressure will come about by the dramatic increase in cross sectional bore area. Since area increases by the square of the bore diameter, doubling the bore size actually quadruples the cross sectional bore area. So lets calculate the pressure required to impress 2503 lbs force on a .50 cal projectile.

Pressure (psi)= Force (lbs force) / bore area (sq in.)

Pressure = 2503 / ((PI*.5^2)/4)= 12,750 psi

Are you surpised? Now think about a few things. The 25-06 isn't particularly efficient at delivering muzzle energy. With a 3200 fps MV, there is alot of friction in the bore. Also its going so fast that the time in which the breech gases have to accelerate the bullet is considerably shorter than in your muzzleloader. So you should see by now. That very, very, effective devastating deer, elk, and grizzly hunting loads can be loaded into your muzzleloader for a fraction of the risk, (and monetary cost), of a three pellet "magnum" load.

In my next, post i will discuss the strength of materials and how pressure translate into stresses within your barrels.

Happy Hunting, Phil