The A1-A2 booster is 1 m diameter and 10 meter long it thrust is 46 tonne (Sea Level) { 51 tonne Vacuum}. This number sets the limit on maximum range even if one stages the rocket in 2 or 3 stages.
The A-IV booster that is 1.2 to 1.3m diameter and 10 m long, the reported thrust of 350 tonne seems a gross outlier and thus most likely an error. Even the Agni-3 with 2 meter diameter and 8.5 m long does not have this kind of thrust.
Also in comparison the massive PSLV core stage is 2.8 m diameter and 20 m long and that generates thrust of about 500 tonne.
IMHO the A-IV booster thrust will realistically be in the range of 75 - 100 tonne. If one can see the video launch frame by frame, and count the time it took to clear its own height(20 m) it will directly tell the acceleration at lift off, and multiply that by weight of the missile (officially reported as 17 tonne, but I think that is impossible, given its diameter and length IMHO the launch weight was >20 tonne) that will tell booster's initial thrust.
The A-IV booster that is 1.2 to 1.3m diameter and 10 m long, the reported thrust of 350 tonne seems a gross outlier and thus most likely an error. Even the Agni-3 with 2 meter diameter and 8.5 m long does not have this kind of thrust.
Also in comparison the massive PSLV core stage is 2.8 m diameter and 20 m long and that generates thrust of about 500 tonne.
IMHO the A-IV booster thrust will realistically be in the range of 75 - 100 tonne. If one can see the video launch frame by frame, and count the time it took to clear its own height(20 m) it will directly tell the acceleration at lift off, and multiply that by weight of the missile (officially reported as 17 tonne, but I think that is impossible, given its diameter and length IMHO the launch weight was >20 tonne) that will tell booster's initial thrust.