Words: Rich Norman

The HK416A5 ecosystem includes a Slim Line hand guard. It is very much Heckler & Koch’s take on a tube rail.

As expected of H&K, they haven’t slavishly copied an existing design. The Slim Line hand guard exhibits an angled front end, Picatinny interfaces at twelve and six O’clock and (surprisingly) it employs a type of KeyMod system on its slick sides; although here it is called HKey. It is said that KeyMod and HKey are incompatible.

Initially I thought the use of HKey was a bad move. M-Lok – a competitor system – seems to have really taken off in the important US market. However, H&K enjoys huge global reach and supplies the armed forces of many nation states. The adoption of HKey could effectively tie countries further in to the H&K ecosystem. So the implementation of HKey could be an excellent marketing move on H&K’s part.

Needless to say the Slim Line hand guard is lighter than the standard A5 quad rail. As its name suggests, the hand guard features a narrow diameter. This is useful in a few ways, but chiefly in that it is ergonomic in the hand and easier to manipulate – the mass of the hand guard distributed nearer the axis of the barrel.

As well as black, it comes in H&K’s signature RAL8000 which could be any colour between yellow, brown and green.

The Slim Line hand guard is not a particularly well known A5 accessory, but it’s been seen in the wild – issued with some European law enforcement A5s.

Two examples…

United Kingdom

(Thanks to Jay Taranis and Chris Cohort Blog for giving me a lead on these pics).


(Thanks Niko for giving me a lead on this photoset).

The same Slim Line hand guard is shown on the HK416A7 below. Note the Cerakote coating on hand guard, receiver and buffer tube; it’s very different from the A5’s anodised finish.


You’ll also notice the extended barrel length. The fire control markings also differ because the A7 employs a 45° selection system as opposed to the standard 90° version on the A5.

Post publication of this blog The Geardo Crow made a really good point about the similarity between the Slim Line hand guard and the new British Army L85A3 hand guard – also made by H&K:

Available in green “RAL8000” in this case, it exhibits the HKey system, an angled front end and Picatinny rails top and bottom.

In the following pics you can also see H&K front BUIS and HKey Picatinny segments:

And H&K rear BUIS – the captive type (note the locking button) as I reviewed here.

But the feedback didn’t stop there. Another reader sent in this awesome pic of a green “RAL8000” A5 with a dropped-in black Slim Line hand guard.

The darker than usual pistol grip and stock show how H&K’s RAL8000 plastics also vary on a case by case basis – these examples being nearer to FDE, in contrast to the mustard yellow RAL8000 mag shown.

Read more about the dropped-in look in the wild, here.

Read PART 2 of this article, here.

Catch up on more HK416A5 news, here:

Fifty Shades of RAL8000 Part 1

Fifty Shades of RAL8000 Part 2

Fifty Shades of RAL8000 Part 3

Fifty Shades of RAL8000 Part 4

Fifty Shades of RAL8000 Part 5

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