M27 Replaces SAW - U.S. Marines

[Evil Monkey]

What about the extra weight of the feed mechanism of the gun?

Negligible for some purpose built one-man belt fed weapons.

KAC LMG weighs 10lbs unloaded.
http://www.knightarmco.com/lmg.html

ares shrike weighs 7.5lbs
http://www.aresdefense.com/

cetme ameli which is under 12lbs
http://en.wikipedia.org/wiki/CETME_Ameli
http://www.imfdb.org/w/images/6/6a/CetmeAmeliIMFDBVer2.jpg

if the mag gets messed up you throw it away and use another one. If the belt feed mechanism breaks you are SOL. Not sure how much of a problem that is, but it is a thought

Large mechanical mags/drums are expensive for large armed forces and are always prone to problems. Some can jam up just by dropping them, which may be inevitable in combat.

Belt feed mechanisms breaking is not a concern. If they were, they would not be in use with professional militaries like the US, UK, etc. Drums and such however, are not in heavy use at all. No surprise.....

Militaries want large loadouts with low weight. For a SAW gunner, a belt fed weapon at around 10lbs is going to be ideal. Large mags/drums just cannot give you the same amount of ammo for less weight and space.

 

[BlueTrain]

For whatever else you might think about it, it seems that short barrels are all the rage these days. I don't know if it makes a difference or not but a lot of the complaints about the M4 carbine on this forum seem to relate to the short barrel and how it negatively affects performance of the cartridge. Is this or is this not a problem and does it matter if the light machine gun/squad automatic also has a short barrel?

 

[Crosshair]

Very interesting designs Evil Monkey, looks like you can get the weight of a belt feed down. Have any of those designs undergone serious testing by 3rd parties or militaries? It would be interesting to read their thoughts on it.

 

[Evil Monkey]

It would be interesting to read their thoughts on it.

The cetme ameli is used by the Spanish military. Haven't read much else about how they like it or how they use it in doctrine.

I think the reason why armed forces have not caught on to using these new light weight belt fed designs is because of two major reasons.

1. These armed forces already have other contemporary belt feds in use, purchased not too long ago, and are still in good shape enough not to be replaced yet.

or

2. They do not use a strong fireteam doctrine to warrant light weight belt feds at fireteam level. Instead, they may still be using MG/rifle group squad formation in which the belt fed MG must be a tough and over built sustained fire weapon served by a crew of two to operate efficiently according to doctrine. PKM, MAG58, M249, MG3, MG43, etc, all seem to fit MG/rifle group doctrine well considering the 15-20lb+ weight, quick change barrel, etc.

I'm guessing that the light weight belt feds I posted probably don't have the life span as, say, and M249. However, they weren't really designed for sustained fire anyway. They're simply a base of fire weapon for each fireteam that have a heavier barrel and just so happens to use a belt instead of a magazine.

 

[HorseSoldier]

Large mechanical mags/drums are expensive for large armed forces and are always prone to problems. Some can jam up just by dropping them, which may be inevitable in combat.

For a sustained fire weapon, magazines also present the problem of not being terribly effective once they're empty. Since magazines are issued as individual equipment, a gunner doesn't get an unlimited supply of them. Whereas belted ammunition is ready to go as soon as you grab it off a truck, kick it out of a helicopter, or whatever. For a weapon intended to pin and plaster bad guys with fire, belts just make much better sense than mags.

See above. In addition, if the mag gets messed up you throw it away and use another one. If the belt feed mechanism breaks you are SOL. Not sure how much of a problem that is, but it is a thought.

Mags are a much more common failure point for weapons (something in excess of 90% of all AR stoppages are magazine related, for instance). I've rarely seen a machine gun just break its feed mechanism on the other hand.