Kunal sir, would you please elaborate, why would you prefer a bullpup like SAR 21 because i think the HK416 and the Bushmaster ACR are better products though of a conventional design.
A Infantry Rifle is always consider better with longest barrel which gives better penetration and range..
SAR-21 PRAIL have more barrel length within small size of the rifle (Bull pup ) heres a comparision:
Heckler & Koch HK416:
D20RS:
1,037 mm (40.8 in) stock extended with full barrel length of 505mm..
Bushmaster ACR:
with stock deployed (mid) 40.8 in
( +1000mm ) with full barrel length of 508mm..
INSAS:
960 mm (37.8 in),464 mm (18.3 in)
Sar-21PRAIL:
805 mm (31.7 in) ( SAR 21 P-Rail), Barrel length 508 mm (20.0 in)
All of these rifle are rugged in rough different terrains, here COST analysis:
INSAS: 450USD
Bushmaster ACR: $2,685–$3,061.00
Heckler & Koch HK416: $1425
SAR-21:$991 ( 1/3 of TAR-21 unit price )
Buying in mass reduce price per unit..
I guess i read somewhere the Kalantak was dropped as the bullet was too powerful for it's short barrel,over heating of the weapon & huge muzzle flash.The new weapon has been named as Multi Caliber Weapon as we all know,but i don't think it is an improvement over the Kalantak as kalantak did not have long range capabilities also i doubt that it could take a grenade launcher.
As i mentioned before Kalantak was meant to replace 9mm carbine from army..
The Idea was is 5.56x45 round in both sub-machine gun and rifle and LMG..
GL can be mounted as the lower-grip is same as regular Insas..