A picture is worth a thousand words ....

That's because no reputable dealer will carry them.

I suggest you surf ebay, or places that sell Chinese knockoffs of Leupold and Aimpoint optics, or collapsible AR15 stocks to fit Moisin-Nagant rifles ... ya know, stuff of equal use, value and desirability.

Seriously, I'd be embarassed to install one on a transferable M16.

Yeah, as a reluctant Colt booster, I'd prolly go with the Colt version (though $272 total is steep) .... but since IMHO it is a useless piece of !@#$% no matter who sells it....

OK, here's the deal:

––A "3-rd burst" fire-control system is useless. Gene Stoner did studies that showed tha in FA if the first round is on-target, the second is way high, the third splits the dif ... and the fourth round would be back on target. But a three-round burst eliminates the fourth round, so limiting to three rounds gives you one good round and tosses the next two away. You might as well switch the selector to semi.

––A "3-rd burst" is unneccessarily complicated and prone to jamming. Look at a milspec safe/semi/auto fire-control group, then look at a 3RB. The S/S/A parts are solid and clear; the 3RB parts are milled much more thinly to allow it to function, creating (A) places for crud to lodge and jam the action, and (B) weak points for things to break.

––A "3-rd burst", as is currently available, is a non-resetting cam. That means if you pull the trigger and decide/need to let off before the full three rounds are fired, the next time you pull the trigger, you only get the rounds remaining in the last burst. Then you must release the trigger and pull it again, to get another burst, or however much of it you want/need.

––A "4-round burst" mechanism takes the above and raises it to Rube Goldberg (check Wikipedia: He created things that accomplished simple tasks in indirect, convoluted ways) device that raises the 3RB to a new level of complexity and, potentially, way more prone to jam. And still does not resolve the non-resetting cam issue.

To me, it's like driving a vehicle with a speed governor, a braking override, and a GPS locked into a voice that tells you every time you've done something that Big Brother does not like. Think training wheels on a Harley. You are surrendering your personal shooting skill to a vulnerable, fault-laden mechanical device that knows better tan you do how and when to shoot.

I take great pride in my trigger control. I can pull off triples and doubles easily, and singles if I concentrate. To me, it is proof that I am qualified to shoot an M16. Otherwise, ownership of an M16 is nothing more than the ability to pay the $200 tax, the cost of the gun, and the ability to create a trust. Which may be a clever enough trick ... but not, IMHO, something to be proud of.

When I introduce newbies to MGs, once the general MG-specific safety issues are addressed and mastered, I work with them to achieve proper trigger control. IMHO, there are two "MG grins" –– the first one comes the first time you shoot an MG; the second, the first time you master trigger control, and can send one, two or three rounds downrange at will. That's an equally good grin.

I have no respect for troublesome mechanical safety devices that remove personal ability from the equation. IMHO, someone who cannot master an MG's trigger simply should not be shooting them in the first place.

If you, or your range, don't want a newbie shooting an MG with more than three rounds per trigger pull ... then only load three rounds in each mag. It's that simple. And when they can do four, load four. Repeat and expand as neccessary.

Because allowing them to rely on unreliable safety devices like burst fire-control systems only installs an unsafe attitude. They are responsible for the firearm, and they must learn how to use it responsibly and safely. Or take it the hell away from them.

Yeah, I'm an old-fashioned fart. Sigh.

sig-x, sorry. BTDT, got the bloody T-shirt.

This may be completely useless, but ... when I'm dealing with newbies, on occasion one of my tricks is to detach the sling from the buttstock, let it fall to the floor ... and slide my left foot forward onto it and hold it down. (Yes, it needs to be long enough/shooter short enough, for this to work.) This, in turn, keeps the muzzle from rising to cable-cutting elevations. Yeah, I know it's cheating, but in some situations it is useful.

IMHO, it's on us, the experienced MG owners, to keep newbies from accidentally doing things that alienate range owners, just as it is our responsibility to keep them from injuring thenselves or others.

Not trying to lecture you. I know you are one of the good guys.

One other trick I've learned: Even shooters experienced with semi firearms don't understand the different dynamics of full-auto fire. So I will do this exercise:

Go up to them, tell them to take a pose with an imaginary rifle and pretend they are going to shoot. Then push them in the recoil shoulder, hard and sharply. Guaranteed, they will fall back (and the aim of their imaginary gun will rise toward the roof/cable). Then remind them that the gun is still firing, and ask them where their gun is pointing. Do it over and over, and they will slowly shift their balance forward, until even the strongest push on their shoulder allows them to keep on-target. Then tell them this is what shooting an MG is like, and that they should take the same stance, and balance, if they want to keep their rounds off the roof.

Just another idea from someone who has seen many cables cut.....