Deadly Precision is the 3rd upgrade for path 1 of the Sniper Monkey. It cost $3400 on Easy, $4000 on Medium, $4320 on Hard, and $4800 on Impoppable. With this upgrade, the sniper monkey can pop 18 layers of bloons at a time, sufficient to pop a whole Ceramic Bloon (Ceramic layer pops in 10 hits, and there are 8 descendants). Since its firing speed isn't high, they would be a lot more effective in groups.
If a Deadly Precision sniper pops a M.O.A.B. by itself, then it will become 64 Blue Bloons rather than 4 Ceramic Bloons. The same thing occurs if it is upgraded to Cripple MOAB. 64 Blue Bloons are very hard to pop for Sniper Monkeys even with x/3. This can be prevented by letting the Sniper deal one hit with 0/0 upgrades, then upgrading it rapidly to 3/x or 4/x. Then, when the M.O.A.B. is popped, it will pop into 4 Ceramic Bloons, which the Sniper Monkey can pop much faster.
The Sniper Monkey's sniper rifle gets a Laser dot sight upon getting this upgrade.
In the official artwork, the Sniper Monkey had a red line on its eye.
A single Sniper Monkey with this upgrade is capable of beating the "20 Ceramic Bloons On The Wall" Random Mission if it also has Faster Firing, but not without losing lives.
Compared with the BTD5 and BMC Artwork, the artwork in BTD5 is more angry than the one in BMC and it is peering with its right eye.