Title Kind of says it all, My dad has a G21, I like it, simple, clean, I'd get something else for myself personnaly, I would like alot more interchangeable aftermarket parts, etc. But, I'm getting off track.

I asked a friend of mine awhile back about Bullets and Guns, whenever I do decide to invest into a High End Rifle of some status, or High End Hand Gun, will firing cheap ammo actually damage the gun. Like say you had a Custom .308 would firing regular .308's and not Match Grade mess with the barrel, such as scar it or damage it permenantly.

Personnaly, me and my dad just fire Winchester 230 gr .45's out of his glock, and don't think an awful lot about it, Blazer and Wolf's just never did it for either of us, they'd have 4 or 5 misfires in every hundred round box and it just, it got tiring, and I was starting to become concerned.

That and they were squirrely what I mean by squirrely is you'd get a tight group of about 4 or 5 and then one would just fly way off, sometimes off target, and I'm almost positive the Wolf's were tumbling or something, they had some of the most akward bullet holes I'd ever seen, it was a long cylinder shape with tattered edges, and a hole at the bottom, It didn't tear clean.  Then again, only the Federal Hollow Points we shot that one day made clean holes, but anyway, enough said, Sorry for getting off topic.

i don't know about using junk ammo in a match barrel but i would guess it wouldn't be too much of a problem other than you won't be maximizing the barrel and your accuracy may suffer some.

but as to the blazer i have tried it in more than a few flavors and i love it.  if you want a step up try blazer brass.  but plinking ammo is just that for sometimes it isn't as accurate or as reliable as carry ammo but that is also why it is cheaper.

i've fired thousands of rounds of Wolf ammo through my SKS and AK without problems.
to answer your question about the 'match ammo' in your .308 simply "no"
you may shoot ANY .308 ammunition from it without problems. you may find the cheapest 150gr. deer load to be more accurate than a 168gr. match load. You just have to experiment with what works.