Some typical US Army demo charges:

Name                              Composition      Weight  Relative
                                                           Effectiveness
                                                           (w.r.t. TNT)

Charge, Demolition: Block (TNT)   TNT              0.25 lb 1.00
                                                   0.50 lb
                                                   1.00 lb

Charge, Demolition: M2 Block      75/25 Tetrytol   2.50 lb 1.20
                                  w Tetryl Booster

Charge, Demolition: M5Al Block    C-4              2.50 lb 1.34

Charge, Demolition: M112 Block    C-4              1.25 lb 1.34

Charge, Demolition: M118 Block    PETN or RDX              1.14
                                           Block:  2.00 lb
                                           Sheet:  0.50 lb

Charge, Demolition: M186 Roll     PETN or RDX      25.0 lb 1.14

Charge, Demolition: Ammonium      Ammonium Nitrate 43.0 lb 0.42
 Nitrate                          w TNT Booster

Dynamite, Military: M-1           RDX              0.50 lb 0.92

To work out the damage in GURPS terms is quite straightforward. Use
the 6dx2 per pound of TNT equivalent and multiply by the weight of
the charge and the relative effectiveness factor. For example, the
Charge, Demolition: M5Al Block weighs 2.50 lb and has a REF of 1.34,
so the GURPS damage is just: (6dx2) x 2.50 x 1.34 = 6dx6.7, or about
6dx7.
     The above charges are squarish and designed to be detonated by
a remote transmitter. A demo expert is needed to: (i) determine the
number of charges of any given type that will be needed, (ii) lay
the blocks in the proper pattern and (iii) set the detonator safely.
     A separate Demolitions roll should be made for each task, with
the last roll being the tricky one.