Check the chamber with a set of headspace guages, (see your local gunsmith) your barrel may not be properly fitted, have seen this once before in a Parker Hale, barrel was not properly set and worked minutely looser with each set of firings, (heating and cooling) Try measuring your brass length also to see how much stretch there is and look for signs of case head separation. Visible signs would be the appearance of a ring around the case head just up from the base. It may not be visible on the outside and but can be felt with a fine scribe like a dental pick on the the inside of the case. If this is apparent then you definately have a headspace problem and gauges will reveal that. Contact your dealer where you purchased the rifle and see about warranty.
Hope this helps,
Pete