Need help!

I got a severe power curve on my rifle and it is shooting nothing like how it shot a week ago. 

I am planning on sending it back and help would be useful because I don’t know how you return and ask for replacements. 

This rifle was bought from field supply about three weeks ago for those wondering.

Thanks, 

Antoni



Edit: Whops! Forgot to say what rifle I got. It was a springer, the Hatsan 1000S striker. For you who said that I got a pcp, I will get one soon but for now I’m stuck with this one. 
 
More info is needed to give you any help. I will take a stab in the dark.

if your rifle is a PCP one of the most common reasons for power to drop is a missing or damaged breach oring. To check forvthat put a tissue over the breach and fire if the air blows off the tissue you need to replace the breach oring. Like I said more info is needed to give accurate help.
 
Please post more details about the gun, etc.

I have had very good experiences with fieldsupply customer service. I purchased an Hatsan AT44-10 25 we on sale and didn't have a chance to put it through its paces sadly until after the return period (family, kids, work, life stuff...). When I pulled the gun out and shot it at 25 yards; it patterned like a shotgun. I contacted FS customer service, explained the issue and they let me exchange (not return) for the same gun at no extra $$. The new gun shot like a champ and I was super happy. Give their customer service folks a try.



Good luck! 
 
....... there's one REALLY friendly gal there that handled my situation very well (my situation's about the same as yours) ....... i got her most times i called cust serv. at field supply . tanya .... 610-837-5940 .... i have handled many hatsan-made air rifles..... ive seen some barrels with only half rifling..... they usually have good barrels , tho, but i could get 3 rifles / case and each one in there would and act differently......some really tumped.... send it back , exchange it . that .25 and .22 striker shoots very hard for a 6 lb gun..... keep it once you get a good one. i have a REALLY good .20 black webley vmx , which was just the jazzed up version of striker1000 when they arrived..........it was a "sleeper".. ... a guy could play around with .25 for under $150 and the .25's i had were more powerful than .25 uk tomahawk , and a .25 cometa 400..... 645 fps with 20 grain ftt pellets. fun... get the wood or camo stock if you can - better resale value... - paul.
 
Antoni, as others have said, you should give them a call. I expect your rifle carries some type of manufacturer's warranty, and the retailer may honor your return on those terms, or you may have to deal directly with the manufacturer. But I think most reputable retailers handle returns in a reasonable manner, since their reputation in the market should be important to them.