Nuclear Weapon

Tactical Warheads:
Types Five to Type Eight where/are used as belt fed mass accelerators ammunition (Most likely in Naval Combat or orbital Bombardment). They have been used on Zaran-7 during the Republic Federation War.

-Type Five:
Sheila Donovan was unable to get more Type Seven for T’sunk’al in 3.Chapter Precious Cargo. So she got him more Type Fives.

-Type Seven:
A crate of Type seven tactical nuclear warheads was sold to T’sunk’al by Johnny. These are later identified as somewhere between Type Five and Type Eight by Jon Wintersmith. It is than added that they where/are used as belt fed mass accelerators ammunition (Most likely in Naval Combat or Orbital Bombardment). They have been used on Zaran-7.

Tactical Type
Tactical Type is most likely a not the designation of a certain design. It is more likely a quantity that combines the dimensions of the warhead in relation to it's yield. It has to fit in the launch-tubes of the belt fed mass accelerators... Following the designation of the armor-piecing ammunition for the AK-D, the actual Warheads most likely follow the same Mark System. E.g. Tactical Type Seven Mark 5: A Tactical Warhead (Meant to be used on a battlefield in military situations mostly with friendly forces in proximity), Type Seven (Yield Seven, similar to Mach Seven being the 7x the Speed of Sound) and Mark five(Design Nr. Five)...

On the other hand the type may be the same as the mark/design. So it would be inside knowledge, if Type 7 has a different yield, better ballistic properties, and/or is just easier to mass-produce than the Type 6....