Do you know what is the chamber specs (223 or 5.56) of the sig 551 swat LE ?
This carbine is chambered in 5.56 not 223 Remington.This means that the firearm will accept both 5.56 and .223 ammo. If it was chambered in .223 the rifle may not have been able to accept military 5.56 cartridges.
The rest of the specs for the Sig SG551 is as follows-
Restricted Law Enforcement/Government Use Only
OA Length 32.8
Weight Empty 7.5lbs