Impact tests in aerospace industries are usually carried out by single stage gas guns. It has three major components namely pressure chamber, valve & barrel. Pressure chamber is used to hold operating gas at high pressure which can be used to accelerate the projectile. Main factor in deciding the design parameters of the pressure chamber is the maximum operating pressure of the working medium. The barrel length plays a major role in the final achievable projectile velocity. This paper talks about designing of the support structures of the barrel for peak recoil load. For designing of the support structures a finite element formulation is made for the assembly of the barrel support and analysed for a peak recoil load. Thereafter, the problem is optimized based on the framework of shape optimization. Considering objective function as to minimize the mass of the support structure and to be able to withstand the recoil loads. The above finite element model is subjected to optimization. Design space is explored for the optimal shape of support structure for a given barrel length using the above-mentioned frame work © 2019 Elsevier Ltd.