SAR 18#6

a rectangular shaped bolt group. The
forward assist is permanently attached
into the receiver and stationary. You
have the appearance but it is non-functioning.
The rail is the typical Mil-Std
1913. Another totally unique feature of
this upper receiver is that the ejector is
screwed into the left side of the inside of
the receiver.
The barrel on the AP4 tested is 16
inches in length with a 1 turn in 16 inch
twist. The barrel is manufactured by
DPMS and is manufactured from 4140
steel and Teflon coated. The barrel has
the step-cut for mounting the M203 (not
that you would) as well as a standard
A2-style compensator. The front sight
base was pinned to the barrel and has
a bayonet lug. Standard large M4-type
handguards came on it with a delta ring.
The charging handle is proprietary
on this design. There is a raised portion
of material on top of the bolt that rides
in a track in the charging handle. The
bolt is also very unique compared to the
rest of the uppers tested. It consists of
two pieces and the recoil/action spring.
The front part of the bolt is not so out of
the ordinary other than the shape. The
piece of metal on the rear is out of the
norm. It is a rather large chunk of metal.
It appears the reason for the large chunk
of metal is not just to take up space but,
due to the mass, will assist on more energy
to drive the bolt forward. Try to picture
bolt carrier bounce on a M4 but reverse
the direction of the bounce. When
two pieces of metal collide and one is
heavier than the other, there will be rebound
due to the physics of the thing.
This would appear to be the logic behind
it – or it could just be a sheer benefit of
the design.
The upper receiver was placed
on the Aero Precision lower receiver.
Only Black Dog Machine magazines
were used. The upper was tested with
CCI MiniMag, Remington Golden Bullet,
Scorpion, Federal Match and CCI
Stinger. This was the only rifle to cycle
the standard velocity Federal match
ammunition. The upper fired all 25 without
a hitch. More than 200 rounds of
the mentioned ammunition were fired
without a single malfunction. The rifle
grouped very well, although the range
was 15 yards.
The DPMS is certainly an excellent
option for one looking for a .22 Long
Rifle conversion kit. The AP4 is a great
all-round upper. The bull barrel version
is great for a competitor or for one who
likes to put every bullet in the same hole.
The quality of this upper receiver is excellent
and with an MSRP $399 it is hard
to beat.
Chiappa M4-22, .22 Long
Rifle Conversion
Chiappa has been known mostly
for blank firing weapons as well as
reproduction firearms from way back
– opening their doors in Italy in 1958.
They opened a facility in Dayton, Ohio
in 2007 to expand their North American
market. Chiappa introduced both their
M4-22 upper receiver conversion and
their M4-22 complete rifle. They offer
three different upper receivers. First is
the M4-22 (CF500-059) upper, which
is a 16 inch government profile barrel.
This upper has standard M4-type handguards
and a polymer upper receiver.
The receiver has a forward assist (nonfunctional),
fired cartridge case deflector
and ejection port cover. The average
selling price is around $350. This upper
comes with a 28-round magazine. The
next is the M4-22 Gen II Pro (CF500-
097), which differs from the standard
by having a 7.8 inch free floating handguard.
The third variation is the M4-22
Gen II Pro (CF500-095), which differs
from the previous by having an 11.8 inch
free floating barrel.
There were three different uppers
tested during this research. All were the
same but with different handguards. The
barrel was equipped with a standard A2-
style compensator. The bolt is a modified
Atchisson. The feed ramp is on the
end of the barrel itself. There is a spacer
SAR Vol. 18, No. 6 72 Nov., Dec. 2014