Hatsan pressure tube problem??

i finally got my hatsan sortie in the mail. Great shooting gun but i noticed one thing. There is a small machined hole or detent in the pressure tube. It holds air very well and it had air in it wen it came. The hole is located neer the front of the pressure tube. I think you can see the treads of the front cap of the presure tube through the hole. Is this hole here on purpose or is it a defect?
,Niels