GPT (Gas tube Pin Tool) is a jig tailor made for installing and
removing the gas tube roll pin on an AR15/M16 low profile gas block.
Machined in 6061 aluminum and Type III hard coat anodized, GPT makes
installing the gas tube pin on a low profile gas block painless. GPT is
designed to be stable and surefooted, but it is no larger than it has
to be, in order to retain a reasonable small footprint on the crowded
Most low profile gas blocks
don't have flats, and are hard to hold steady without requiring 3 hands
to install the diminutive gas tube roll pin. GPT enables the user to
install the gas tube roll pin, and remove it as well with ease.
made its base thick and wide for stability, its base is rebated to
allow the user to clamp it down in a vise. Thoughtful touches can be
found on the GPT, from the scalloped finger access recess to the soft,
rounded corners and edges, even its green color has a purpose. Most gas
blocks are black, we wanted GPT to be anything but, as we found it more
difficult to work on a black gas block that sits in a black jig. GPT's
green color provides a pleasant contrast and makes the black gas block
With a small Neodymium magnet placed
on the gas block, it's powerful enough to stand the gas tube roll pin
can upright, perpendicular to the gas tube, above the gas tube pin.
With one hand holding the gas block steady in the GPT, one can start
tapping on the gas tube roll pin to get it started.
GPT is a collaboration between Modern Armory
and Forward Controls Design.
with most gas blocks including Modern Armory, the GBF (Gas Block,
Forward Controls), BCM, Rainier, VLTOR, Knight's Armament, Badger
Ordnance, Daniel Defense, SLR, or other low profile gas blocks based on
the original Crane design.
measure your low profile gas block dimensions, as some are longer than
others. GPT is made for Crane Mk12 pattern low profile gas blocks, the
length of which is 1". GPT can be modified to accommodate longer gas
MAX gas block length: 1.00
MAX gas block height: 1.35
Known incompatible low profile gas blocks: Aero, Luth AR, and DPMS, and adjustable gas blocks.