gadget, you sound like you're trying out for a white shirt (or maybe you already have one

)
True enough but in a world of civil-liability we will never see .308 semi-automatic rifles in the hands of regular patrol officers (Canada only discussion),
Never? There's already precident - both the RCMP and OPP issued FN CA1's at one time - not a large scale issue, but they were issued on a limited scale never-the-less.
based on the fact that limited penetration ammunition's is cost prohibitive for large departments
You're assuming here that one WANTS limited penetration ammo for the .308's. Don't fall into the trap of thinking that ALL policing in Canada is of an urban nature; there's A LOT of rural policing being done in this country. Ever try to shoot a moose or a grizzly with limited-penetration ammo? Not to mention a vehicle engagement with limited penetration rounds. Want limited penetration? Use the .223/.556. Want more penetration/terminal ballistics? Take the .308.
I didn't say in my original post that a .308 should be standard issue - I referred to them being held at the detachment/office level (like they are now in a bolt-action platform) for the incidents when more than a .223/.556 is needed.
based on evidence produced from FBI-Gunsite-International Wound Ballistic Association tests for urban environments the 223-556 projectile offers less of a threat due to over-penetration and defeats soft & certain hard armor options that could be encountered.
Here you've fallen into that "URBAN" trap again. Try to avoid that Big-City mind set that there's no life (intelligent or otherwise) outside of the big lights....
Yes, I happen to have an official copy of the FBI Ammunition Data And Sniper Material CD direct from the FBI Academy Ballistic Research Facility in Quantico, VA. It is a wealth of information, and shatters a lot of pre-conceived notions regarding BOTH the .223/.556 and .308.
Don't forget about the ballistics research done by DDS. Garry ROBERTS since the now defunct International Wound Ballistic Association stopped publishing.
Also, don't discount the RCMP ballistics research done by the likes of Dean DAHLSTROM and Kramer POWLEY, some of which was published in the IWBA's journal.
You mention " the 223-556 projectile offers less of a threat due to over-penetration", I assume your reference is in relation to the .308, but many don't realize that the same holds true to the .223/.556 penetrating less than most police service pistol ammunition as well.
Yes, the .223/.556 will penetrate SBA and some HBA as well, but the .308 will do both as well, if not better, as well as being much better against vehicles.
Also those on the board that have done or are involved in police firearms training will testify, that the 308 platform would only be for hand picked officers,
As a matter of fact, you just happen to be talking to one of whom you refer....., and in case you didn't know, evil .308 platforms are already available to lowly NON hand picked GD police officers in Canada, albeit in bolt-action daylight-only capable platforms.
since the 308 platform does produce more recoil, and will be difficult for smaller stature officers to master.
Just what do you think a 12 gauge shotgun is? Low recoil?
A semi-auto .308 recoils less than a six pound pump-action 12 guage shotgun, even with "low recoil" tactical rounds, which practically all police agencies still issue.
Again, you seem to be inferring that I'm suggesting general-issue .308's instead of .223/.556, which I'm not.
While you're on the subject of recoil though, here's the beauty of having the same weapon system in two different calibers - the majority of training is done on the .223 as it should, and when something bigger is needed, all the operating controls, all the drills, all the ttp's are the same. Wow, just think of it, police firearms selection and training that actually makes GOOD sense for once!
That being said and done the 223-556 platform is woeful in vehicle engagements (KevinB & Big Red can add much to this area of discussion),
Not to knock or belittle in any way either KevinB or Big Red, or their considerable experience, but in case you weren't aware, there are actually quite a few members on this forum who have experience either shooting into/out of/through vehicles, and/or dealing with/examining the nasty mess left inside; most prefer anonymity for personal security reasons. And I think that I can speak for all of them in that they don't appreciate being spoken down to.
That aside however, there are some things that can be done with the .223/.556 to enhance it's effectiveness against vehicles such as using either the 55gr or 62 gr Federal Tactical Bonded (I point you towards the US DOJ/DEA New York Firearms Unit report on Ballistic Performance Tests on Motor Vehicles), and I've heard good things lately about Barnes X-Bullets against vehicles as well. I have yet to personally shoot any vehicles with any weight of the Barnes X (hoping to remedy that soon), but I have shot numerous vehicles with practically every 55gr and 62gr military ammo, and most weights and brands of civvy .223 in addition to both weights of the Federal Tactical Bonded, as well as a variety of military and civvy .308 and other calibers; based on my limited experience, if it's targets in and around vehicles, and the choice is .223/.556 I'll take one of the Federal Tactical Bonded, and preferrably the 62gr. And no matter what .223/.556 we're talking about, it's still not as good as a .308 in or around vehicles though.
and full-auto is not an option for patrol officers and most would argue has no place in a tactical unit either. In the right platform the 308 combined with the right ammunition & training would be an asset, but based on budgets and the scrutiny of police administrators we are not going to see any large scale deployments of this platform outside of specialized units.
I don't think anyone is aguing "for" full-auto. I do agree that in the right platform the 308 combined with the right ammunition (ie. NOT limited penetration) & training would be an asset, but I don't agree that this platform will never be issued outside of specialized units - it just has to be presented to the police administrators from an aspect of willful blindness on their part and of liability falling on THEM. And since we were never discussing large scale deployments in the first place, that shouldn't be an issue, so to speak.
The whole thing comes down to training - right now there are agencies who issue a service pistol, a 12 gauge shotgun, and a .308 bolt action rifle (and a few perhaps a patrol carbine as well) - it's a sad fact of life, but training on TWO weapons systems is often overload for many police officers, what with reluctance from management to spend time and money on training, especially when some agencies are permitted only 4 (yes, four) hours of firearms training per year, which in addition to practice qualification and actual qualification, must also include reviewing policy, stoppage drills, basic marksmanship principles, etc, etc.. But now we're potentially looking at training on FOUR weapons systems, that's just waaaayyy too many; in my humble opinion, it's two too many.
In my perfect world we'd get rid of the shotgun and .308 bolt action, and we'd have just two weapons systems: the service pistol and the same rifle "system" in both .223 and .308, and if that system happens to be the HK MR series, all the better. Same training, same everything except caliber.