This article is from the can.talk.guns FAQ, by Skeeter Abell-Smith firstname.lastname@example.org with numerous contributions by others.
What is an assault weapon? Assault _rifles_ are selective-fire (semi-
or full-auto) weapons that are often smaller calibre. Assault rifles
have been prohibited since 1978 (except for about 4500 Canadians who
owned at least one before 1978). No registered automatic (i.e. machine
gun) has ever been used in Canada in any violent crime or suicide.
Banning the semi-automatic rifles too-often called "assault weapons"
makes little sense, since the semi-auto rifles that remain legal for
hunting and other purposes are usually more powerful. (It takes more to
knock down a moose than a human.)
As for "military-style" or "paramilitary" firearms versus "domestic" or
"hunting" rifles: the distinction is useless. There are rifles used
for hunting and sport that were/are of military origin and there are
firearms that are/were used by the military that began as "hunting"
rifles. The designs are similar and basic. The goal of each is the
same: force a piece of lead out at high speeds. Both "military" and
"hunting" rifles are available in semi-automatic. (e.g. The "civilian"
Colt AR-15 is actually the predecessor of the military version: the
M-16. In spite of this, it is usually classed by the media as a
"military- style" weapon.)
Semi-automatics patterned after state-of-the-art firearms technology
used by the military and popular with millions of responsible gun owners
offer increased reliability and durability.
It makes little sense to ban rifles because of their appearance while
ignoring performance and function. There is more about this in the
coroner's report on the murder of 14 persons at L'Ecole Polytechnique.
Semiautomatics which externally resemble automatics are difficult to
convert to automatic and such a conversion is illegal and subject to a
ten-year jail term. There is no evidence that semiautomatic firearms
are disproportionately used in crime. Through 1988-1991, 20% of all
firearms homicides involved prohibited weapons, 60% involved ordinary
hunting rifles and shotguns, and 20% involved handguns.
Semiautomatics targeted by anti-gun legislation could affect more than
30% of the guns legally owned by Canadians. The cost of replacing these
firearms could cost Canadian taxpayers in excess of $2,000,000,000.
 Juristat Service Bulletin Vol. 11 No. 12 op. cit., p. 13