There are few reasons let me point them out >>
1. The primary purpose of mortars is indirect antipersonnel fire.
The mortar bomb's wounding power comes mainly from high-velocity splinters, not sheer explosive power. Range and lethal frag radius of 81mm and 120mm mortar bombs were pretty similar ..
2. One can always
haul a lot more 81mm bombs/charges than 120mm within the same given weight and space limitation.
3. You can call in 81mm fire support closer to friendly troops under attack because of the 81mm mortar bomb's reduced HE payload as compared to the 120mm bomb.
4. Rate of fire is higher in case of 81mm means more rounds on target ..
Besides all these points, IA wanted to retain BMP-2 Amphibious capability so 81mm suits the need, But let me put this clear, 81mm does not have the punching power to decimate buildings that 120mm Has ..
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@Ray sir, Your view about the comparison between 120mm and 81mm mortars ?
They should have placed 120 mm mortar on BMP-2's, what is the rationale behind mounting 81mm mortar on them?
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AMOS and NEMO and have automatic computing, loading and laying. They shoot extremely fast after stopping and at short ranges they can fire multiple rounds on different trajectories that will impact on the target simultaneously.
One thing mortar has over artillery is the high trajectory. In urban areas hitting streets without hitting the nearby buildings with mortar is possible, artillery not so much.
Also, does any country operate auto-loading system on mortars?
