I started playing around with editor the other day and noticed you can kill some armor with small arms fire if you aim for certain weak points on certain vehicles. I wouldn't recommend you using as a offensive tactic but more of a "no other choice " option. I will add more weapons/vehicles/weak points later.

If you have a link to all of the weak points in arma's vehicles or if someone has already done this that would help greatly.

Here is a very rough estimate of how bullets it takes before the crew bails on certain areas of the vehicle and with different weapons. All of these shot are perfect aim so it will probably take you many more bullets to take one down.

BMP2
First the BMP2 pretty tough vehicle but has a major weakness in its front vent but if your not at the right angle go for the treads.

Front vent
m16.......m240.......m249
45.........40-50.....70-100

Treads
m16........m240......m249...m107
45-60.....20-30........40........*

BRDM2/ATGM
Very easy vehicle to get the crew to bail with even with an m16 just aim for a tire and unload.

tires
m16.....m240.m249 m107
20.........10......25....7-9

rear armor
m16....m240..m249...m107
60-70....*........*.......*

Shilka
Evil is the best to describe this vehicle and only been able to find one weakness in its treads. though the treads seem to be very weak.

treads
..m16.....m240..m249...m107
15-30....20......40.......6-7

T-72
very tough vehicle! its weaknesses are still very strong you're pretty much better off hiding or running away.

back tanks
m16............................................... ....m240.......m107.........m249
takes more bullets than you can carry.....100-150......45....... ineffective?

Treads
?

Treads
When shooting treads if your hitting them from side it may take you a LOT more bullets to damage them than hitting them head on. So try to get your self in front or the rear before unloading on a tread.

*ps. would be very nice if someone would unlock posting urls for me i would post pictures of the weak spots im not a spammer ok!