I think I have a PCR-5 only because it appears to fit the desciption: 16" barrel, A2 sights, muzzle brake.  But on the left side it actually says PCR99. I haven't been able to figure it out using the serial number. All I know is that it was made in 99. Oly's website not much help but I did get a basic email answer when I asked. Oly's response was only a guess based on the sketchy info I provided.  Can you help?

I thought that "Politically Correct Rifle" was the model designation.  Mine says "MOD P.C.R. 00".

Hey, that's it. That's what I have. So does that make it a PCR-5 for sure?

PCR stands for Politically Correct Rifle.  The other two digits signify the year of manufacture.  The only way to know what model you have is to know the descriptions of each.

PCR-1 Flat-top 20" or 24" barrel, free float handguard
PCR-2 A2 carry handle, 16" barrel, free float handguard
PCR-3 Same as PCR-1 but with 16" barrel
PCR-4 Standard A2 20" rifle
PCR-5 A2 16" rifle
PCR-6 Same as PCR-4 except in caliber 7.62x39mm
PCR-7 16" eliminator (same as Bushmaster dissipator)
PCR-SM 20 DCM competition model gun (SM=Service Match)
CAR-97 16" carbine (has fixed open stock of post-ban models)

Hope this helps some