Table I

Sound pressure levels (SPLs) of FN P90 personal defense weapon with and without Gemtech SP90 sound suppressor using SS190 supersonic and SB193 subsonic rounds. SBLs and first-round pop (FRP) are recorded as decibels.
Gun	Caliber	Suppressor	Supersonic	FRP	Subsonic	FRP
FN P90	5.7x28mm	None	161g	n/a	153h	n/a
FN P90	5.7x28	Gemtech SP90	134g	+0.2	120h	+0.2
M4A1	5.56x45mm	None	165e	n/a	151f	n/a
M1A1	5.56x45	Gemtech M4-96D	135e	+0.8	119f	+2.3
HK MP5	9x19mm	None	157a	n/a	155a	n/a
HK MP5SD	9x19mm	HK integral	127b	+11.1	126b	+13.0
Marlin 780	.22 LR	None	143c	n/a	140c	n/a
Marlin 780	.22 LR	Ciener Integral	124d	+0.5	121d	+0.8
a Winchester USA 115gr supersonic FMJ b Samson 158gr subsonic FMJ c Federal high velocity LR d Hanson standard velocity LR e 62gr M855 ball f 55gr subsonic; Engel Ballistics Research, Rt. 2 Box 177C, Smithville, TX 78957 g SS190 supersonic ball h SS193 subsonic ball