The only explanation from a ballistics perspective is that you have very slow velocities in the neighborhood of 700 ft/second. If you have access to a chronograph you could verify that.

if its not that slow you can really rule out ballistics or bullet issues, the math doesnt lie! get a speed exiting the barrel, if this slow, you have powder issues ( i would guess). if 2-3X this , it isnt the bullet or powder , look for aim issues.. ie lose site, bad aim, you.. ect....
just throwing out there, are you using the correct caliber bullets?