SAR 18#6

to ammunition. Every manufacturer of
these conversion units recommended
high velocity or hyper velocity ammunition
to make the rifle fire reliably.
Although the ST-22 went out of production
in January of 2013, there are
still many upper conversions as well
as complete rifles out there. This is a
high quality conversion that has had a
lot of time and thought gone into it to
make it that much better than some of
its competitors. Hopefully at some point
Spikes Tactical will put them back into
production. Tom Miller at Spikes Tactical
told this author that they have everything
they need to go right back into
production when the time comes.
Core15 .22 Long Rifle Conversion
Core15 is one of the newest manufacturers
in the AR-business out of
Ocala, Florida. When they opened their
doors they hired Israel Anzaldua, formerly
a Bushmaster senior executive,
to assist them in getting going. They
have very quickly gained a reputation of
being one of the higher tier AR manufacturers.
They make rifles in 5.56mm,
7.62x51mm and .300 Blackout. They
manufacture .22 Long Rifle conversion
uppers only, not complete rifles. Core15
introduced their .22 Long Rifle line up
in December of 2011. They offer 5 different
variations: M4, MOE, TAC, TAC
III with 12 inch rail and the TAC III with
a 15 inch rail.
The upper receiver received for test
and evaluation was the TAC III with the
15 inch rail. The MSRP on this particular
upper is $629.99. The upper receiver is
a standard 7075 T6 aircraft grade aluminum
upper receiver with a forward assist
(looks only), fired cartridge case deflector
and ejection port dust cover. The
charging handle is manufactured from
a solid piece of 6061-T6 billet aluminum
allowing it to be held to extremely consistent
tolerances and maintain exceptional
level of strength. The charging
handle is equipped with the Core15 V2
tactical latch.
The 16 inch barrel is nitride coated
and equipped with a standard A2-
type compensator. Core15 currently
out-sources their .22 Long Rifle barrels
to Green Mountain but are in the process
of manufacturing their own barrels.
As of this writing, Core15 is manufacturing
their own 5.56mm barrels. The
barrel on the test and evaluation unit is
manufactured from 4140 steel and has a
twist rate of 1 turn 16 inches. The handguard
provided on the test and evaluation
unit is the Midwest Industries Gen
2 SS series handguard. The handguard
has a 1.5 inch outer diameter and is very
light. The rail is manufactured from 6061
aluminum and uses a proprietary barrel
nut that must be installed by a gunsmith.
The rail is set up so that there are removable
rail segments that allow the
user to only put on what is needed and
not to worry about the others being damaged.
The provided upper was equipped
with two of the 2-inch rail panels mounted
at 3 and 9 o’clock on the front
of the handguard.
The bolt is a modified Atchisson design.
This design has an interchangeable
front that is held in place by the
receiver frame. The bolt group is made
from 4143 stainless steel. This particular
one is equipped with a barrel collar
assembly that contains the feed ramp.
The barrel end slides into the barrel collar
assembly. The bolt group is nickel
boron coated.
The upper was tested solely with
Black Dog Machine magazines and
placed on the Aero Precision lower receiver.
The upper was tested with CCI
MiniMag, Remington Golden Bullet,
Scorpion, Federal Match and CCI Stinger.
Approximately 200 rounds were fired.
Like all the rifles before it and after it, the
upper would not cycle with the Federal
Match ammo due to it being standard
velocity. However, the best groups were
shot with this ammo. Other than that, the
rifle cycled reliability with all the ammunition
it was fed. Core15 recommends
CCI and Winchester ammunition and
stated their uppers have zero issues
with CCI Stingers.
Core15 offers 5 variations that cover
any customer. They are very high
quality but expensive. You do get what
SAR Vol. 18, No. 6 70 Nov., Dec. 2014