well you could send it back, use a penny, or blade opener (sometimes you find the remington, winchester, or other blade openers on ebay, also if you call magnum boker in colorado they have them for sale for around $6.96 apiece I believe).
Other wise you could leave it half way open, but if it is significantly hard to open (due to the backspring) it could take a year, or more to loosen the backsring. Have you tried a lubricant to see if it helps at all?