Home Reviews Thermold Mag Thermold M4 Hi-Cap

Thermold M4 Hi-Cap

by Arnie

M4 Hi-Cap

by Arnie

Capacity ~350
Black ABS style material


may remember back on April
25th we mentioned
a new type of magazine that a Taiwanese
company were going to make some new Thermold style M4 magazines,
well a sample has arrived for us to have a look at.

magazines come from a company in Taiwan, and Wilson
(the owner) can be contacted at wilson22@ms18.hinet.net.

new magazine is a hi capacity replica of a “Thermold”
magazine. I know little about the real magazine, other than
I gather it should be fairly popular with anyone with a Canadian
interest as their military use it ^_^ :

magazines were developed by Master Molder in Wilson, South Carolina,
and were “pitched” to the US military as a replacement
to aluminum “USGI” mags, but the US military was unable
to come to an agreement with the owner. Master Molder then licensed
the design to the Canadian military, who manufactured a version
of the Thermold 30-rounder as the standard-issue magazine for
their military.

magazines are made from a dark gray polymer and have anti-tilt
followers. They have several reinforcement ribs across the lower
half of the mag body…”
mag FAQ

Here’s a TM M733 with the Thermold mag compared to the standard
metal mag we are used to seeing (and another chance to show
off my rather overused hall carpet).

Thermold mags certainly look very different, and a welcome change
from the “norm”.

I wasn’t too keen on taking this mag to bits.. as my experience
with things that go “boing, ting” isn’t the
best in the world.

said I found that I had a minor problem with the mag,
as the internals wouldn’t feed BBs from the reservoir,
so taking out my trusty (and well used) Leatherman, I
set to getting this piece to bits to find out the problem.

You’ll have to excuse the colour in these photos but I
did the work at my desk after the sun had gone down. ^_^

thing to do is unscrew the bottom, then slide the lower
cover off, you will then find that the internals slide
out the top of the mag cover.

up, you need to separate the two halves that make up the internals.
First remove the screws and the cir-clip that hold the central
wheel on. Make a careful note of the positions of the non return
spring and the top spring.

I found on mine that the little wheel that ensures one BB at
a time get’s into the feed hop had come loose, and that the
spring that held it in place (doubles as a non-return latch
on the main wheel) had come out of place.

the left hand shot (above) the wheel is loose and sprung against
the loading wheel, and in the right hand side it is back in
place. I am very sure that this has happened in shipping after
it arrived in the UK. The parcel probably received a sharp nock
getting moved from van to van.

reassembling, I kept the non return spring in place with the
point of a screwdriver to ensure that it stayed put while I
assembled the two halves.

is dead easy really, just be sure to get both the springs back
into place, and gently turn the wheel to align the gears when
you reattach the two halves of the mechanism together.

ensure that it couldn’t happen again, I put a slight bow in
the spring to bend it tighter against the gearbox. Sure the
item might have been faulty out the box, but it was dead easy
to fix.. and sadly was more that likely down to the courier,
so don’t let the minor niggle put you off.

The mags have been assembled from an ABS style
plastic not dissimilar from that of the stuff used to build
the ‘Heavy Weight’ TM springers. The base is held on by a philips
head screw, which is very nice to see.

(RHS shot in natural light, LHS in flash light
to show colour contrast in both lights)

up everyone that’s lost the bottom of their TM hicap at some
point? Yeah though so.. the G3 series seem to be particularly
bad at this. I’ve had 2 out of 5 that have needed the good old
gaffer-tape solution to keep the bottom on. Suffice to say there’s
little chance of that with this new mag. If you want to be sooper-dooper
safe you could take the screw out and stick it back in with
a little lock-tite, but it is in fairly tight to begin with.

lower wheel is easy enough to turn (although it might not be
so easy with gloves as it’s recessed), and handily has an arrow
printed on it to indicate the rotational direction to turn it.
Okay.. I knew which way to turn it anyway, but try the same
thing on a Saturday morning skirmish “the day after the
night before”. Yup we’ve all been there.

good news is that if you have difficulty winding the lower wheel,
a complete wind empties the entire mag, so you won’t need to
wind it in the field (in theory).

is a mould seam along the side where the two halves have been
mounted together. If you are bothered about it, a quick touch
with a Dremel sanding/buffing tool will sort that one out for

Weight is 150g (empty), compared to the TM M4 standard mag’s
200g (empty) – so it’s roughly 25% lighter. Fitment into the
M4’s mag well is a nice secure fit – there’s almost no lateral
or horizontal movement. The mag will not fit into a ClassicArmy
M15 (the new M4) mag well without adjustment. It seems the CA
mag well is slightly shorter (from front to back) by about 0.5mm.

feed hole at the top of the mag is the usual shape and size,
but the latch cover is a nice tight fit. This is due to the
presence of a lip at the rear of the sliding cover that ensures
the cover stays closed.

will find that the M4 mag catch drags over the top of the mag
and catches slightly on the top seam. It’s not so much a mag
flaw as just an issue with the mag loading system really. As
you can see in the photos of both the TM mag and the Thermold
mag, the catch drags seriously on both mags causing a groove
to appear on both, so you should find any catching problems
will fade away after light usage (these mags shown have seen
less than 10 changes).

Well the new mags will certainly bring a rather unique
look to any M4-alike they are fitted to and not only are
they cheaper, but they take 350 rounds, 50 rounds more
than the TM 300 normal round hi-cap. I suppose the only
downside at the moment is that there are no mid-cap or
lo-cap versions available, but you never know on that
one. The minor niggle with the feed mech is not one that
I I would worry about. If you do get one that doesn’t
work the solution is easy, and my problem was more than
likely caused by the courier dropping the parcel.

one Wilson! With an expected RRP of much less than the
TM equivalent M4 300rnd hi-cap (I won’t publish
the dealer prices so as not to offend anyone), not only
are they cheap, but provide a completely different look
and feel to any M4.


sure to bring a more unique look to a plain old M4


Top notch only a few mould seams

for Money

A true bargain – cheaper than TM mags


Fix that minor niggle with the spring getting loose
and “you’re the winnaaar! ^_^”

(the owner/manufacturer) can be contacted at wilson22@ms18.hinet.net.


on this review in the forums

Friday, May 30, 2003 8:42 PM
Copyright 2003 ArniesAirsoft

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