There is NO problem in taking long most long guns into Canada.
A single form can be downloaded from the Canadian Firearms Center website. This form can be filled-out in advance, but NOT SIGNED until actually in front of a Canadian Border Officer. Payment of a $25 fee allows you to import up to three guns, and the form is a temporary registration certificate valid for 60 days.
The firearms center website is at:
www.cfc-cafc.gc.ca
and on the lower right side of the homepage is a link to "information for visitors/non-residents".
Magazine capacity limits apply, and some long guns, mostly miltary or service-type semi-autos, are in a different class from "sporting" guns. Details are on the CFC website.
Before paying heed to a lot of BS about the 'problems', go to the Firearms Center website and learn the FACTS.
Also, make sure you have your guns viewed and certified by Customs on the USA side of the border, so you can bring them back in without a hassle.
Three of us crossed with seven rifles and 500 rounds of ammunition in 2005, and we're going back this year. The crossing was simple in both directions, and the most time was spent in the US border post getting the guns looked-at and serial numbers etc. validated.