Round pieces injection resulting squared problem

We have created an injection mould for round sticks. After injecting with several materials with different melt flow index, changing prsuure, temperatures, injection speed, etc all the pieces turn out to be squared, with the diagonal bigger then the diameter set in the mould erosion.

Do you have any advice in what could us be doing wrong, or what probably we did wrong.

Thanks in advance for any advice

could you paste a photo of the part and injection gate position please?
also information about used material and if you made a filling study

Where is the gate? Gate size? Gate style? Mold and melt temps? What's the part length? Normally these are extruded due to these reasons.
Rick