Missouri Bullet Company bullets are hardness optimized and coated to reduce the amount of lead left in the barrel so you can spend more time shooting and less time cleaning your guns. An optimally hard lead bullet is simply one which obturates at a given pressure sufficiently to seal the bore against the gases which would otherwise “cut through” the soft lead (called “gas-cutting”, forcing molten lead into your rifling. A bullet which is too hard won't obturate and seal the bore, because the gas pressure is insufficient to expand the base of the bullet. A bullet which is too soft at a given pressure will experience excessive base expansion and vaporization of the lead, causing leading.
A common conception is that when it comes to lead bullets, harder lead equals less leading. This is a false perception! To explain this surprising statement, it is necessary to discuss the physics of getting the bullet out of the barrel and how lead residue comes to be deposited in the bore. When the powder charge ignites, pressure is generated. Lead is a soft metal. Its hardness is expressed on a standard scale, called the Brinell Hardness Number (BHN.) The BHN of the bullet interacts with the pressure generated by the burning powder. The mechanism of this involves the effect of the generation of thousands of pounds per square inch of pressure which causes the base of the bullet to expand, or “obturate”. Properly obturated, the base will have expanded beyond its original diameter which has the effect of “sealing the bore” against the explosive pressure of the gases burning behind it. Properly sealed, and working in conjunction with the lubricant in the lube groove, the bullet will thus not allow gases to escape forward from around the base of the bullets, which prevents it from shaving lead from the bullet body and forcing it into the bore grooves (otherwise known as “leading”.) This failure to obturate (“seal the bore against onrushing gases”) causes leading which is a chore to clean and is a major obstacle to accuracy.
The Missouri Bullet Company optimizes bullets for your intended application. They don't take a “one size fits all” approach to manufacturing your bullets. MBC works with certified analysis foundry alloy in two hardnesses in order to provide you with the bullet hardness that works best for you. One is 2% tin, 6% antimony, balance lead for harder bullets at 18 BHN and the other is 1.3% tin, 4% antimony, balance lead for bullets optimized for lower velocities at 12 BNH. While it is expensive to maintain a dual supply of alloy, the payoff is in the fact that you have a choice of bullet hardness suited for your particular application.
The Missouri Bullet Company also utilizes a Hi-Tek coating on bullets to eliminate the need for messy lubes while loading ammo. The coating itself consists of a catalyst which binds a polymeric colorant agent with acetone which is then applied in bulk to raw bullets and baked onto the bullets' surface at nearly 400 degrees. The coating is a polymer (bonded with metal) and forms an extremely tough new surface for the bullet. The application of the coating is repeated for an additional coat. The bullets are then sized normally but not lubricated, as the coating itself acts as bullet lube. Nominal bullet diameter is not affected.
Many indoor ranges prohibit the use of lead bullets but allow the use of coated bullets due to the fact that no lead is exposed to the environment. Leading of the bore is dramatically reduced, as is lube smoke. Long shooting sessions do not have to be interrupted by bore cleaning. Higher velocities can be attained with Hi-Tek coated bullets. There are also associated health benefits for the reloader, as there is no touching of bare lead. Hi-Tek also reduces the force required to seat and crimp because the bullets are slippery. The bullets actually look "wet" and are very slippery. This lubricity reduces friction-related heat as the bullet traverses the bore. In summary, Hi-Tek coated bullets offer the advantages associated with plated bullets without the expense.