In the 1970s the US military looked to replace the existing M60 machine gun with a squad weapon in 5.56x45 NATO calibre. They decided the Belgian FN Herstal Minimi was most suited and it was adopted as the M249.
US Special Operations Command (USSOCOM) specified various adaptions which became the Mk46 Mod0. They also specified the need for a 7.62x51 NATO calibre version designated the Mk48 Mod0.

The NZ Defence Forces use the FN Minimi 5.56 but have decided to upgrade to a 7.62 version, the FN Minimi 7.62 TR. Visually the main differences with the Mk48 Mod0 are the sliding butt
and lack of rail above the barrel. There is also a Mk48 Mod1.

I purchased a cheap Chinese model that had some resemblence to the Mk48 Mod0. Unfortunately it was only about 85% the size and some major differences.
I decided to throw away any chance of having a working BB gun and set to work.

The major differences were:

1. The charging handle was on the wrong side

2. The scale meant it looked better suited for 5.56 rounds

3. There was no carry handle (ok, some 'Para' models had a shorter barrel and no handle ... but this wasn't one of them)

4. The gas valve was missing below the barrel ahead of the front sight

5. The vehicle mounting lug was also missing under the barrel behind the bipod

6. It had a standard assault rifle box magazine. Only the 5.56 Minmi has the capability of using box magazines as well as ammo belts.

When I unpacked my new toy I broke the bipod within seconds of taking it out of the polystyrene packaging. Then I spent some time convincing the suppliers (ASGC) to send me the missing front grip/torch.

PS. Don't ever turn the torch on - it shows a changing multicoloured display like a snail disco.

By the time I received those I had already trimmed the underside rail to fit a vehicle mounting lug, and created a gas valve in front of the sight. I bought another thin bipod from TradeMe that wasn't too different
from the original but which gave me a much greater support - the original plastic bipod legs had bowed outwards under the weight !!
Mounting that was interesting and involved an aluminium insert to strengthen the plastic where the bipod mount screws tightly. The new bipod is on the gun in the right photo, above.

I machined back the raised patterns on the left side but stopped short of removing the projecting slide that the charging handle used to move along. I shifted the handle
to the right side along with some shaped aluminium to stand in for missing parts. I routed a hole through the ejection flap on the right and created a new flap
that I stuck out at about 65 degrees, even though it would spring back flat in the real weapon after each casing is ejected.
I also burred a hole above where the desintegrating links would eject from.

I also cut away the solid plastic ends of the top rail. In the real gun this is a metal housing with holes and no ends.
Unfortunately in this Chinese replica those solid ends help hold the gun together ... oops!

Various markings, like "MADE IN CHINA" and extra holes I created were covered with a stiff tape to try and create a smooth surface to paint later.
The ammo belt intake was carefully shaped in cardboard - it became just too difficult in aluminium. If it fails at any point I will probably try again with aluminium instead using the previous cardboard as a template.
I also removed the large knobs on either side of the rear sight. Some pictures of the real steel show them and many don't. I preferred them without...

I decided to make a handle and a 100-round pouch magazine. I had acquired a 100-round pouch for a Minimi which was for 5.56 and so too small to use. However it gave me the necessary detail to make my own.

For the pouch magazine I found a plastic container ('Cuisine Queen' 2.2 litre) and the bottom matched the size and shape I needed. I cut it carefully and used a paint stripping heat gun
to soften the plastic enough to bend the way I wanted. It colled and hardened in that shape nicely.
Then I sewed some camouflage material I had lying around (as you do!) with a zip and riveted the bag I had made onto the plastic case. (See original parts below)

I then mounted it to the gun using the top half of the supplied box magazine because it already fitted into the magazine hole, which shouldn't be there anyway.
I did remember to remove the BB spring before cutting the magazine in half! Add in some belted 7.62 NATO tracer rounds (red tip) and it looks fairly authentic.

Then for the handle I used a speed paint brush handle and a shaped rod from a replacement paint roller handle (see parts above). I need to reshape the rod a little and create a plug
for inside the handle that would accept the end of the rod to jam the handle onto one end of the shaped rod.
The handle was mounted to the gun with a shaped piece of 5mm thick aluminium bar (not an easy job to wrap it around the rod tightly).

Then some paint - makes a huge difference. Unfortunately the photos highlight the uneven pieces of tape after painting whereas in real life they are hardly noticeable at all ...