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