A gas spring assembly for securement between spaced first and second associated structural components (USC, LSC) of an associated vehicle, said gas spring assembly comprising: a first end member adapted for securement along the first associated structural component of the associated vehicle; a piston assembly (104; 104') spaced from said first end member with a longitudinally-extending central axis disposed therebetween; and, a flexible wall disposed about said axis and secured between said first end member and said piston assembly (104; 104'), said flexible wall including a first open end and an opposing second open end; said piston assembly (104; 104') including a piston body (118; 118') and a retainment ring (120; 120'), said piston body (118; 118') including a first end disposed toward said first end member and a second end disposed away from said first end member with an outer side wall extending at least partially therebetween; said second end including a base wall adapted for securement along the second associated structural component; said first end including a first lateral wall portion extending approximately transverse to said axis and an annular wall portion extending axially from said first lateral wall portion generally away from said second end; said second open end of said flexible wall having a cross-sectional wall thickness, said second open end received on said annular wall portion such that a substantially fluid-tight seal is formed between said second open end and said annular wall portion; and, said retainment ring (120; 120') including a flange wall, said retainment ring (120; 120') received on said first end of said piston body (118; 118') such that a distance between said flange wall and said first lateral wall portion is greater than said cross-sectional wall thickness and a gap is thereby formed between said flexible wall and at least one of said flange wall and said first lateral wall portion, characterized in that said retainment ring (120; 120') includes an axially extending annular side wall, said flange wall of said retainment ring (120; 120') extending radially-outwardly from said side wall, and said annular wall portion of said first end includes at least one projection extending radially outwardly and including a projection end wall disposed toward and extending in approximate alignment with said first lateral wall portion. a first end member adapted for securement along the first associated structural component of the associated vehicle; a piston assembly (104; 104') spaced from said first end member with a longitudinally-extending central axis disposed therebetween; and, a flexible wall disposed about said axis and secured between said first end member and said piston assembly (104; 104'), said flexible wall including a first open end and an opposing second open end; said piston assembly (104; 104') including a piston body (118; 118') and a retainment ring (120; 120'), said piston body (118; 118') including a first end disposed toward said first end member and a second end disposed away from said first end member with an outer side wall extending at least partially therebetween; said second end including a base wall adapted for securement along the second associated structural component; said first end including a first lateral wall portion extending approximately transverse to said axis and an annular wall portion extending axially from said first lateral wall portion generally away from said second end; said second open end of said flexible wall having a cross-sectional wall thickness, said second open end received on said annular wall portion such that a substantially fluid-tight seal is formed between said second open end and said annular wall portion; and, said retainment ring (120; 120') including a flange wall, said retainment ring (120; 120') received on said first end of said piston body (118; 118') such that a distance between said flange wall and said first lateral wall portion is greater than said cross-sectional wall thickness and a gap is thereby formed between said flexible wall and at least one of said flange wall and said first lateral wall portion, characterized in that said retainment ring (120; 120') includes an axially extending annular side wall, said flange wall of said retainment ring (120; 120') extending radially-outwardly from said side wall, and said annular wall portion of said first end includes at least one projection extending radially outwardly and including a projection end wall disposed toward and extending in approximate alignment with said first lateral wall portion.