Better crits is pretty pointless for bursters, the table for uncalled shots has "low" modifiers.
0-20 x1.5
21-45 x1.5
46-70 x2
71-90 x2
91-100 x2
101+ x3
If you said mults are unchanged.
So with BC perk you'll roll 19-119.
It's 27% that you'll deal x1.5 damage.
55% that you'll deal x2 damage.
19% that you'll deal x3 damage.
While without BC perk:
45% that you'll deal x1.5 damage.
55% that you'll deal x2 damage.
I'm not taking knockdowns into account, but I don't know on what roll they are because it could be changed in FOnline +Stonewall perk will negate it, but not all snipers have 6 ST and 10 EN I think, so knock downs will be possible.
Edit: I just want to say that with BC perk BG burster has 19% to "insta-kill" target with very much damage.
Also 10 LK doesn't worth it, it only increases critical chance on 4%, so it's better to have 6 LK, but 10 AG and burst much more often, and if you want to have 10 AG and LK, then you'll have low EN and/or ST. Anyway bursts/time with 10 AG and Jet+Psycho with 21% crit is much more better than few bursts with 25%.
And 19% to make x3 damage is almost every 5th critical burst.
Edit#2: Oh and yea something like "I deal 69 damage with critical hit with avenger!!1" may be it's possible I don't know, but I had "tests" too, when I saw a guy who bursted me with simple (not avenger) minigun for 50-60 damage regulary non-critical, and I was wearing BA and x1 Toughness. So if you're shooting from avenger, you will deal more than 50-60, then multilpy it on 3, and you'll have instakill, and if you're shooting in point blank somehow, then you'll see huge number of damage, and it'll be cool. Find a bluesuiter and just arm avenger mini with JHP ammo and critically burst him with better critical on max rool, I think there will more than 1k damage, it's cool! ^_^ Ehm.. anyway, better criticals should be very useful for bursters.