I would get a budget AR15 like a DPMS sportical or smith and wesson MP15(they average about $600) and get the 22 conversion. it's just a 150 bucks plus about 50 for mags so for about 800 dollars you end up with roughly 2 guns. you can change the bolt and mags in the field if you want. a 22LR bullet is a .223 bullet and a 223 is actually a .224 so there is a slight difference but since the 22lr is smaller than the designed barrel it will not mess it up. you will experience slightly diminished accuracy but if you are doing open sighted shooting at a 25 yard indoor range then you wont even notice a difference. trying to shoot a 223 out of a 22lr barrel would worry me a lot more than the other way around. all in all I think that $800 for a multicaliber rifle with mags included is a pretty good deal
ignore my complete lack of capitalization. I still have no problem correcting your grammar.
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