In terms of armament production and weapons technology, the Ottomans remained roughly equivalent with their European rivals throughout most of the seventeenth and eighteenth centuries. The theory that Ottoman cannon foundries neglected mobile field guns by producing oversized siege cannon at a disproportionate rate has been debunked by the military historian Gábor Ágoston. Despite the Orientalistic claim that an inherent conservatism in Islam prevented the Ottomans from adopting European military innovations, it is now known that the Ottomans were receptive to foreign techniques and inventions, and continued to employ European renegades and technical experts throughout the seventeenth and eighteenth centuries. In terms of productive capacity, the Ottomans were even able to surpass their European rivals during the seventeenth century. They maintained full self-sufficiency in gunpowder production until the late eighteenth century, and with rare and brief exceptions were continually able to produce enough cannon and muskets to supply their whole armed forces as well as surplus stockpiles. According to Gábor Ágoston and Rhoads Murphey, Ottoman defeats in the 1683–99 and 1768–74 wars with the Habsburgs and Russia are best explained by the strain on logistics and communications caused by multi-front warfare rather than Ottoman inferiority in technology and armaments, as such inferiority, insofar as it existed at all, was far less significant than had formerly been believed. It is now believed that the Ottoman military was able to maintain rough parity with its rivals until the 1760s, falling behind as a consequence of a long period of peace on its western front between 1740 and 1768, when the Ottomans missed out on the advances associated with the Seven Years' War.