FMJ Ammo vs TMJ Ammo
FMJ (Full Metal Jacket) ammo and TMJ (Total Metal Jacket) ammo are two types of ammunition among the many other types. These two differ from other types because they do not expose the lead core. The main difference between FMJ and TMJ ammo is the degree to which the lead is enclosed. In TMJ ammo, the entire lead core of the bullet is enclosed in a jacket of a different metal. In FMJ ammo, the covering material extends from the tip down to the sides only. The base of the bullet is not covered, and the lead is still exposed. It is difficult to identify FMJ and TMJ ammo by eye as the base of the bullet would be covered by the casing.
The main advantage of TMJ ammo is the reduction in the amount of lead that is spread in the air. Lead is a very soft metal that easily vaporizes under the extreme heat and pressure conditions that it experiences during firing. The jacket at the base of the bullet in TMJ ammo prevents the lead from vaporizing. You can easily gauge how much lead is vaporized in FMJ ammo by comparing a fired bullet from one that was just yanked from the casing. A fired FMJ bullet would have a pit where the lead was vaporized.
Lead is a harmful substance when an excessive amount is taken into the body. Therefore, inhaling the vaporized lead in the air from your FMJ rounds can affect your health; especially if you spend a lot of time in the firing range, and if there are a lot of people firing FMJ rounds. Because of this, some firing ranges, especially indoor ones, require the use of TMJ ammo only. FMJ ammo is banned because the enclosed area can further increase the concentration in the air and further expose the shooters to health risks.
FMJ and TMJ ammo perform identically, and you probably won’t notice any difference when using either of the two. Using TMJ ammo is advised when practicing, especially in enclosed areas, as the increased number of shots can spread a lot of lead into the air.
Summary:
1.FMJ ammo has the lead core exposed at the base while TMJ ammo has the lead totally enclosed.
2.FMJ ammo spreads more lead into the air than TMJ ammo.
3.Some ranges require the use of TMJ over FMJ ammo.