Modeling The M84 Flashbang Grenade

[swaghauler]

I am at the point where I need to standardize my rules regarding "Distraction Devices" and how they stun. I have been using STUN for Concussion/Impact rounds (like shotgun beanbag rounds) but my players recently acquired a few M84 Flashbangs for an OP. Here's my initial thought on how to do it.

M84 Flashbang Grenade: Wt: 0.25kg, Bulk: 0.8 (I use Bulk in ENC), Burst Radius: 2m*, Price: $50 S/S.
A blinding and deafening explosion producing 6 million Candela and 180 Decibels and capable of igniting flammable materials inside its 2m Casualty Radius (0n a 1 in 20).

I would roll for FRAGMENTATION as though the flashbang were a Frag grenade, anyone facing away would be treated as one fragmentation band farther away (ie secondary burst radius). Each "frag hit" would be 1D10 and ALL the "frag hits" would then be added together and then divided by the various target's/victim's CON scores to determine how many 1-Second Initiative Steps they would be affected by the grenade.

Any thoughts on an alternative method guys?

* I have 4 Fragmentation ranges.
The Casualty Radius (1/2 RAW Burst Radius) where Concussion and Frag are full value.
The Primary Burst Radius (RAW's normal Burst) where Concussion is HALVED but Frag chances remain the same.
The Secondary Burst Radius (1.5 X RAW Burst) where there is only Fragmentation.
The Tertiary Burst Radius (2 X RAW Burst) with a reduced chance of Frag.