How Can This Happen?

I cannot get photos to upload. I did use soapy water and determined a leak existed at the fitting on the end of the pump hose that connects to the gun at the middle of the terminal fitting on the hose.

For an adapter for the rifle cylinder I started with an AV SS Female DIN W/Male QD, which did not fit into the pump hose fitting at all.

I then bought an AV SS Female DIN W/Male 1/8" BSPP. This does screw into the hose fitting and seems like a good connection but soapy water reveals a leak behind the female terminal of the pump hose where the metal base of the hose fits into that terminal. It looks as if the correct adapter should fit more snugly and close up that interface which is now loose.

I ordered an AF Foster Female QD to 1/8" BSPP Male and hope when it comes in that it solves the problem. But I am not confident as all three adapters were recommended by the experts. Perhaps the manufacturer will have a determinative answer.


 
Now I think I know what's wrong in your setup. 

Check the hose connector as shown in the picture below. Do you see a convex , cone-shaped surface ? 

1556016414_3858499875cbeed1eb42234.33557960_Capture.JPG


I bet you have bought this adaptor : https://www.airgundepot.com/pcp-adapter-din-female.html

From your description, it seems that the adaptor cannot be fully screwed into the connector of the hose hence the observation "where the metal base of the hose fits into that terminal.... that interface which is now loose". I believe the sealing washer shown in the picture below is obstructing it . Try to remove it and connect again. That sealing washer is for a different type of connector, not that on your pump's hose

1555990512_16117607895cbe87f0ae1484.48725592_Capture.JPG


If my guess is right, you have never pumped any air into the rifle but just into the atmosphere. That 120 bar of pressure in the rifle's air tube must have come with the gun. 
 
Airgunfans, that gives much clarity for me. 

I spoke today with Chris of Hill Pumps and he is going to run this by some other guys there. 

I was able to explain things fairly well I think and it is because of the education you guys have given me here on this thread. I'll let you know how it turns out. 

You guys have been like Sherlock Holmes figuring this all out.
 
I am happy to report that Chris Dale of Hill Pumps in England has solved my problem. I was able to send him photos of my connecters, adapters, etc. and he had several questions. He then coordinated with Air Arms and he determined that I needed a different adapter.

Remarkably, he is sending me the adapter free of charge. Hill Pumps was extraordinarily responsive to my problem and solved it very quickly, despite the fact that there was no issue with their pump, but rather, with the adapters I was sold by others. Count me as one more huge fan of Hill.
 
I am happy to report that Chris Dale of Hill Pumps in England has solved my problem. I was able to send him photos of my connecters, adapters, etc. and he had several questions. He then coordinated with Air Arms and he determined that I needed a different adapter.

Remarkably, he is sending me the adapter free of charge. Hill Pumps was extraordinarily responsive to my problem and solved it very quickly, despite the fact that there was no issue with their pump, but rather, with the adapters I was sold by others. Count me as one more huge fan of Hill.

Thats excellent, nice work forum members and Hill. Great news.