Bucky tries to deflect with his arm and gets shot on the knee caps because Kingsmen aren't retarded fodder.
Ignoring the feat where he jumps over them rather than blocking them?
Falcon was firing in a predictable line and the bullets hit the ground inches away from him before he started flipping, Falcon isn't a reknown Marksman anyway and neither is anyone who fired at Bucky.
The only one who's tagged Bucky is Widow and she got him with an eye shot (A high end for her) Eggsy and Harry can get consistent head shots with ease which you can't say that any other MCU character with the exception of the Punisher has managed to do.
If Bucky did manage to some how predict that Eggsy/Harry would shoot his knees instead of bionic arm repeatedly like the idiotic fodder that fights Bucky all the time they still have the deadly Neurotoxin that can one shot Bucky and considering Eggsy avoided getting tagged by Gazelle (Who is leagues faster and more agile than Bucky) he has a good chance of incapacitating Bucky or killing him at the least.