"The Fw190A8 was not an up gunned 190, the Fw190A8- R2 was an upgunned Fw190A8."
And if that is not clear enough let me rephrase it: There was no general variant (190AX or 109GX or KX) of German fighters that was "built for bomber interception" (as has been erroneously referred with 190A8).
Later variants had more Rüstsätze (field conversion) so that planes could be equipped with what ever loadout was needed for specific missions, and of course there were more options for bomber interception tasks too. In 190 series this was probably more possible due to new wing introduced with A6. It was not exactly like "plug and play" but the conversions were easy enough to be made in the units. Umrüst bausätze (/U2 etc) were bigger (factory) conversions of the earlier and some later models which eventually resulted e.g. in F and G variants of 190 along with "Mistel" and torpedo bomber variants.
"again semantics. So the Fw190 A-8 R-2 wasn't a FW 190 A-8.? It's like calling a P-47 D -11 a completly different plane than the P-47 D-40.The wing cannon upgun wasn't a bolt on addition it was a upgunned version of the A-8 with a designation. Maybe they should have called it a FW 190 A8 1/2 so theres no confusion."
Actually thats not any friggin semantics but a knowledge of what was the basic or most representative loadout for which variant. You could argue that with A7 which half of the production was delivered with R2 conversion but that would make what, 40 aircraft? If you look at the conversion types you'll notice that all Rs for A8 (actually from A6 onwards) are for bomber interception but that is because (from A5 onwards) there already was F (and for some time G) variant which took care of ground duties. The basic A8 had two MG131s and four MG151/20s and was meant a fighter. Sometimes seen with just two inboard cannons but I guess it was easier to leave the outer guns out and just plug some R under wing if needed without need to disassemble the outer wing bay to remove those 151/20s.
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Why 30mm in 109 then? In numbers a single MK108 was more effective than a single MG151/20. How useful was it in aircombat then? Well, surely if you need to make a deflection shot its not as good as 151/20 but if you get a freebie from 6 o'c at an unalarmed target (as claimed to represent 80% of planes shot down in WW2) even one hit would be enough -and against an occasional bomber four hits could be enough +no additional drag and a small change in weight. Of course MK108 was considered a better choice for such a small fighter.
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A pretty comprehensive listing of 190 variants (although some which I doubt ever existed):
http://www.ww2aircraft.net/forum/aviation/best-fw-190-variant-712-19.html-C+
