the reason for this was big mouth of OFB.everybody knows the capability of these MPVs and Maoists are putting larger IEDs now,which sometimes consists as much as 80 Kg HE.
read this....
This targeting of an MPV followed a landmine blast carried out a few days earlier in which another MPV was paralysed. While this earlier incident involved the use of eight kg of TNT equivalent of explosive material, in the September 3 incident, the Maoists multiplied the quantity of explosive material by ten times! Thus, the first lesson was learnt! The lesson was: ‘an MPV has the capability to withstand only a certain limited quantity of TNT equivalent of explosive material’. The website of the Ordnance Factory Board (OFB), in fact, gives in splendid detail all the design features, technical data, protection capability and the stabilised remote-controlled weapon station that is mounted on the MPV! It notes that protection is limited to “14 kg TNT under tyres, 10 kg TNT under hull and 10 kg IED on side walls”. On the other hand, an MPV without RCSS feature can withstand a mine blast of “14 kg TNT under wheels and 10 kg under hull”.
The Maoists did not have to experiment to know how to defeat an MPV. All the details are available for the asking!
Maoists understand the limitations of Mine Proof Vehicles | Institute for Defence Studies and Analyses
just like this,we know that around 150 kg HE could disable/destroy an MRAP,Maoists too will plant massive IEDs and will target these new MRAPs.