Visitors may import non-restricted firearms (shotgun/rifle) into Canada for legitimate purposes:
• sporting or hunting use during hunting season;
• use in competitions;
• Import 200 rounds duty free for hunting purposes, or up to 1,500 rounds duty free for use at a recognized competition.
When entering Canada with a firearm a Nonresident Firearm Declaration must be completed.

• The declaration is available at all border crossings, but can be downloaded and filled out prior to arrival.
• CAFC 909 Non-Resident Firearm Declaration Download
• Fill out Three Copies.
• ••DO NOT•• sign the Form(s).
• Leave blank areas on the form that you don't understand.
• If you have more then three firearms: Continuation sheet (CAFC 910) - PDF
• The declaration is good for 60 days. It cost $25 Canadian, paid at point of entry. You can receive an extension to your Declaration from the Chief Firearms Office for the province you are visiting.
To extend your Declaration, call the Canadian Firearm Center and they will connect you. The extension must be granted prior to the 60-day expiry and requires no additional fee.
• You must be at least 18 years old to bring a firearm into Canada.
• The declaration is only valid for the person who signs the declaration.
• You can be processed by Canadian Customs in under twenty minutes.

If you are taking hunting guns to Canada, be CERTAIN that you fill out the US Customs Form 4457 with description of gun, expensive cameras, watches, computers, electronics and etc.) & serial numbers and present to US guys before leaving US (so they will have record that you took them out & didn't purchase in Canada).

GETTING THROUGH CUSTOMS: CANADA BORDER CROSSING… KNOW BEFORE YOU GO.

More than ever the port authorities are being very strict on their requirements in allowing visitors across the border. In the past, one sole conviction of DUI usually  wasn't a problem. Lately, the immigration officials may deny entry to these people. It is imperative that you be aware of this information in advance before planning your hunting trip. Anyone convicted of any felony or misdemeanor may require a permit to enter into Canada. 
The applications can take between 6 weeks or up to 6 months to process. An offense that occurred between 1 and 5 years, would only qualify for a TRP (Temporary Resident Permit). This would be issued with an expiry date. Any offense between 5 and 10 years would qualify for Rehabilitation. This is a lifetime permit that would not need to be renewed.
If, in the past, one received the TRP to enter, they cannot travel again expecting to receive the same approval. It usually is a one time permit, and the port authority will explain that the proper way to apply for permission to cross the border can take several weeks or months to process.
Often, one sole minor conviction over 10 years ago, would not even require any special permission to enter. Keep in mind, that the various ports of entry, whether by land or air, offer different services and are open at different times. The above services may not be offered at all offices.It is wise to contact  Lucy Perillo, Canada Border Crossing Services, located in Winnipeg Canada for more information.  1-800-438-7020. www.bordercrossing.ca