“I’ve not seen any police statement that they have obtained the bullets that injured the two officers and matched those bullets to the pistol in question.”
Me neither so as far as anyone knows the guy they arrested may not even be the shooter. I assume they won’t know til the ballistics tests come back. Although you would think that the police could get a working theory just by looking at one of the bullets that get removed from the injured officers. If there are any. A .22 and a .40 are pretty different in size.
A point to note about long-range shots with apparently inaccurate weapons: During the Hundred Years War in the fourteenth and fifteenth centuries, the primary English infantry weapon was the long bow, with a draw of about 140 lb. and an effective range of a little over 200 yds. Few, if any, English archers were able to hit individual French knights at that range. However, they didn’t have to because the French charged the English in densely pack formations, meaning the English archers just aimed at those formations, and slaughtered thousands of French men at arms. The cops being in a tightly paced riot formation, a similar thing could have happened at Ferguson.
The wounds will tell the story though.