KMDO
12-23-2002, 02:25 AM
I thought this might be of some interest. I knew the 7.62 has some differences than the 308 Win but never knew the throat was so different on the little ones.
.223 Rem VS 5.56mm
by
Paul Nowak
05/04/2001
.223 Rem VS 5.56mm
There are a lot of questions about these two
cartridges. Many people think
they are identical - merely different designations
for commercial and
military. The truth is that, although somewhat
similar, they are not the same
and you should know the differences before buying
either cartridge.
The cartridge casings for both calibers have
basically the same length and
exterior dimensions. The 5.56 round, loaded to
Military Specification,
typically has higher velocity and chamber pressure
than the .223 Rem. The
5.56 cartridge case may have thicker walls, and a
thicker head, for extra
strength. This better contains the higher chamber
pressure. However, a
thicker case reduces powder capacity, which is of
concern to the reloader.
The 5.56mm and .223 Rem chambers are nearly
identical. The difference is in
the "Leade". Leade is defined as the portion of the
barrel directly in front
of the chamber where the rifling has been conically
removed to allow room for
the seated bullet. It is also more commonly known as
the throat. Leade in a
.223 Rem chamber is usually .085". In a 5.56mm
chamber the leade is typically
.162", or almost twice as much as in the 223 Rem
chamber. You can fire .223
Rem cartridges in 5.56mm chambers with this longer
leade, but you will
generally have a slight loss in accuracy and
velocity over firing the .223
round in the chamber with the shorter leade it was
designed for. Problems
may occur when firing the higher-pressure 5.56mm
cartridge in a .223 chamber
with its much shorter leade. It is generally known
that shortening the leade
can dramatically increase chamber pressure. In some
cases, this higher
pressure could result in primer pocket gas leaks,
blown cartridge case heads
and gun functioning issues. The 5.56mm military
cartridge fired in a .223
Rem chamber is considered by SAAMI (Small Arm and
Ammunition Manufacturers
Institute) to be an unsafe ammunition combination.
Before buying either of these two types of
ammunition, always check your gun
to find what caliber it is chambered for, then buy
the appropriate
ammunition. Most 5.56mm rounds made have full metal
jacket bullets.
Performance bullets - soft points, hollow points,
Ballistic Silvertips, etc.
- are loaded in .223 Rem cartridges. Firing a .223
Rem cartridge in a
5.56mm-chambered gun is safe and merely gives you
slightly reduced velocity
and accuracy. However we do not recommend, nor does
SAAMI recommend, firing a
5.56mm cartridge in a gun chambered for the .223 Rem
as the shorter leade can
cause pressure-related problems.
Winchester Law Enforcement Ammunition East Alton
Illinois
.223 Rem VS 5.56mm
by
Paul Nowak
05/04/2001
.223 Rem VS 5.56mm
There are a lot of questions about these two
cartridges. Many people think
they are identical - merely different designations
for commercial and
military. The truth is that, although somewhat
similar, they are not the same
and you should know the differences before buying
either cartridge.
The cartridge casings for both calibers have
basically the same length and
exterior dimensions. The 5.56 round, loaded to
Military Specification,
typically has higher velocity and chamber pressure
than the .223 Rem. The
5.56 cartridge case may have thicker walls, and a
thicker head, for extra
strength. This better contains the higher chamber
pressure. However, a
thicker case reduces powder capacity, which is of
concern to the reloader.
The 5.56mm and .223 Rem chambers are nearly
identical. The difference is in
the "Leade". Leade is defined as the portion of the
barrel directly in front
of the chamber where the rifling has been conically
removed to allow room for
the seated bullet. It is also more commonly known as
the throat. Leade in a
.223 Rem chamber is usually .085". In a 5.56mm
chamber the leade is typically
.162", or almost twice as much as in the 223 Rem
chamber. You can fire .223
Rem cartridges in 5.56mm chambers with this longer
leade, but you will
generally have a slight loss in accuracy and
velocity over firing the .223
round in the chamber with the shorter leade it was
designed for. Problems
may occur when firing the higher-pressure 5.56mm
cartridge in a .223 chamber
with its much shorter leade. It is generally known
that shortening the leade
can dramatically increase chamber pressure. In some
cases, this higher
pressure could result in primer pocket gas leaks,
blown cartridge case heads
and gun functioning issues. The 5.56mm military
cartridge fired in a .223
Rem chamber is considered by SAAMI (Small Arm and
Ammunition Manufacturers
Institute) to be an unsafe ammunition combination.
Before buying either of these two types of
ammunition, always check your gun
to find what caliber it is chambered for, then buy
the appropriate
ammunition. Most 5.56mm rounds made have full metal
jacket bullets.
Performance bullets - soft points, hollow points,
Ballistic Silvertips, etc.
- are loaded in .223 Rem cartridges. Firing a .223
Rem cartridge in a
5.56mm-chambered gun is safe and merely gives you
slightly reduced velocity
and accuracy. However we do not recommend, nor does
SAAMI recommend, firing a
5.56mm cartridge in a gun chambered for the .223 Rem
as the shorter leade can
cause pressure-related problems.
Winchester Law Enforcement Ammunition East Alton
Illinois