The simulator incorporates {HEAD ~ a liquid or solid spring} for simulating {TAIL ~ the force pulse} on a projectile during firing of the projectile 
for simulating
The simulator incorporates { HEAD ~ a liquid or solid spring } for simulating { TAIL ~ the force pulse } on a projectile during firing of the projectile
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH