PMCI - May 2021

With SIG’s new modular system, the trigger and corresponding
inner workings known as the fire control system are housed into
a small metal structure which bears the actual serial number.
When inserted into the frame, the serial number can be
seen through a small window cut out in the polymer grip
frame. This allows the end user to use the same modular fire
control unit in a compact M18 grip frame and switch it out for
any other size frame offered in the series without changing the
integrity of the overall design and legal definition of the pistol.
Last fall, the folks at SIG Sauer sent over samples of the M17 &
M18 320 on the heels of our coverage of the SIG 320
LEGION here in the pages of PMCI Magazine. As fellow writer,
Clint Steele did a well thought out overview of the M17 to kick
things off, I continued to work with the M18 in comparison to
what we liked and may have originally disliked about the larger
version. Ultimately, it was determined the only real difference
between the two new models was simply about an inch more
barrel and slide on the larger duty sized M17.
Both Clint and I really liked the SIGLITE Front / Night Sights
and the fact the rear sights were on a removable plate set up
for directly mounting one of SIG’s top performing ROMEO1 red dots.
Neither of us seemed to be a fan of the manual safety. With
over two decades of shared time in on striker fired platforms,
a safety seems a bit out of place. This would simply take more
time to get used to.
Like the M17 320, the M18 shipped with a flush fit 17 round and
two extended 21 round magazines for added firepower readily
assessable. These steel magazines are built like tanks and offer
the shooter a high level in confidence in their reliability. Just
having eight extra rounds in a standard load out was a great
feeling straight out the gate! Like the standard SIG Carry model,
the M18 is considered a compact size and a direct challenger
for those like me who used to regularly carry a Glock model 19
with a standard 15 round magazine. Unlike the box Glock, SIG
pistols are known for being more curvy, contoured, and sleek
feeling in the shooters hand. The M18 is no exception as it
seemed to fit my hand like a glove.
M18 vs 320: What is the difference? The most noticeable
difference in the M17 / 18 submitted for military trails and
civilian models aside from the obvious coyote PVD coating
of the M series was the inclusion of an ambidextrous thumb
safety to meet military specifications. This slight change to the
original specs of the 320 series got a lot of people’s attention
started driving more attention to the existing 320 line.
M18 vs M18 320: Is there a big difference? The short answer
is no. The only difference as explained direct from SIG Sauer
representatives is that guns produced for the military trials
featured matching a FDE colored trigger, take down, magazine
release and slide lock lever. The civilian versions simply feature
the controls in a contrasting black finish.
FIREARMS - SIG M18 320