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Posted: 5/14/2008 3:26:59 PM EDT
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Hey Everyone, I am planning on replacing my full auto fire control group with a Colt 4 position FCG on my M16A1. The four positions are "Safe, Semi, Full and Burst". I have never installed or used a burst FCG and I'm not sure how I would install one. So as I understand it this 4 position kit has the 3 round burst parts in it, so it would be the same as installing a plain old 3 round bust fire control group. Anyway my question is, does anyone know where I can get some online documention on how to install a burst kit, or more specifically the 4 position kit? I have looked all over and all I can find is a document that explains "how the 3 round burst works", but nothing about installing it. Any help would be greatly apreciated. Thanks! |
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I can't answer your question, but I CAN say that I've seen countless posts on here saying "don't bother" whenever the 4-position fire control group comes up. Everyone says that they kept it in maybe a week, then decided that "burst" was a completely useless selector position and removed it. In fact, it's been posted so often that someone has a labeled set of three photos showing each configuration. I expect it to be posted within the next 24 hours.  Just some food for thought while you wait for an response that is actually useful. 
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I personally wouldn't listen to the people that tell me "You don't want it" or "You don't need it". Only I can really decide that. I do respect the (many) opinions of others. I say Go for it. If nothing else, you shouldnt have a problem selling it on the EE based only on the number of times this has come up in the last few months. It installs like any auto FCG kit. Instead of one disconnector, there are two. I don't know if every single tiny spring or pin is the *exact* same as the FA kit so just use all the parts that come with it. |
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jhm is correct -- that's the great thing about life in the United States: You're free to do whatever you want and buy whatever you can afford. I'm personally not a fan of burst in M16s. In fact, in the 25 years since they were invented at the request of U.S. Army bean counters, the only people I've ever met who liked them were those very same bean counters. They were a bad solution to an even worse problem: The military didn't want to spend the money for enough ammo to give soldiers adequate training, and they knew that inadequately trained riflemen tended to freeze on the trigger and dump mags when under fire. So they came up with a burst limiter -- the firearms equivalent of training wheels. To do this, they took a straightforward fire-control system and turned it into a Rube Goldberg-worthy system of cams and gears, about tripling the number of places where crud could lodge and jam the rifle, and greatly increasing the odds of something getting out of adjustment or breaking. I've often suspected it was a secret Soviet plot and prolly designed by Michail Kalishnikov -- after all, it make his AKs look that much better in reliability comparisons. They didn't even bother to make it a true resetting burst -- which means if you get off the trigger after two rounds, release, and then pull it again, you only get the one round remaining in that burst. Four-position FC groups take the above complexity, and reliaiblity issues, and increase them by one-third. Sigh. Four-position FC groups serve one useful purpose: At MG shoots, they make it easier to spot the newbies and go over to introduce yourself. No one else would own them, and they generate a lot of behind-the-back smiles among the longtime MG owners. I consider personal development of trigger control both a challenge and a badge of experience. Pick a number from one to 30, and that's how many rounds I shoot in a burst. At first it's difficult; after awhile, it becomes second nature, and really no biggie. (I'm not saying I always hit the target; but I do control the precise number of bullets in the vicinity.) Some defend burst FC groups as a useful tool for introducing full-auto first-timers. I just teach them the way I learned: First shoot in semi, then put three rounds in a mag and switch to auto. With support, explanations and demonstrations, and close supervision, I've never had a problem, and they always go away with both the full-auto grin and pride that they could control the MG with their trigger finger. I'm not sure the pride would be there if they used training wheels. As always, Your Mileage May Vary. 
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Well I haven't completely made up my mind on it. I figure it couldn't hurt to have one and learn how it works. I can always throw my FA FCG back in it. Also it might be one of those things that I only use the semi and auto selections and never use the burst. I don't really see how it could hurt to have it there... Anyway I am mostly interested in finding some sort of document that explains how you install the burst cam onto the hammer and what looks to be some sort of spring that goes with it? When I see the picture of the actual parts online, I try to visualize how they go together, but it looks confusing. I guess it would be nice if you could simply pull the trigger real quick and have it cough out 3 rounds no matter how long or short you hold down the trigger. Anyway thanks for the input and if anyone has an actual install guide for burst, I'd love to see it!  Thanks! |
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I have found one persistent good use for my 4-pos FCG - on my dedicated .22LR gun. Cyclic rate of my ceiner .22 conversion on full auto is almost 1600rpm, and 3rd burst provides a nice controlled little squirt, while still giving the option to dump the mag when you want, which only takes about a second and a half. 3rd burst on a spinner at 50 yards or so hits the spinner twice at the bottom, then has raised just about enough for the third to smack it back down as it comes up over the top - great fun. In .223, I'm not fond of 3rd burst - which is easily provided by your trigger finger without any burst reset issues. I've made custom 2rd burst cams before, which are potentially more useful in a combat situation, since the first two are minute-of-man close, while that third round in most bursts is always a wasted high-right flyer. The little spring on the burst cam is a torque spring - holds the burst cam on the hammer axis, while still allowing it to rotate relative to the hammer, but only in one direction. Due to the spiral wind of the spring, when you attempt to rotate the burst cam relative to the hammer in the direction of the spring spiral, it clamps down, and doesn't move, while going the other way slightly expands the spring from around the hammer axis, allowing it to rotate to the next cam position. Sort of how a pipe wrench grips in one direction, and relaxes its grip in the other. |
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The Colt 4-Way parts install just like the standard 3rd burst parts in an M16A2 or M4. You can download the Army M16/M4 technical manual at: www.ar15.com/content/manuals/TM9-1005-319-23.pdf As for the Colt 4-Way parts themselves, I have had them in my rifle at one time and they were of very high quality and worked 100%. I have since removed them for the very reasons tony_k mentioned above. I found myself never using the burst setting, I did not like that the burst did not reset, and the trigger pull in semi varied depending on what position the burst cam was in. If you do decide to go with the 4-Way parts anyway, here is some additional info. The hammer, burst cam and trigger are the same as an M16A2 hammer, burst cam and trigger. The parts that are different are the 2 disconnectors, the auto sear and the selector. Below are pictures showing these components. The M16A2 parts are on the left and the Colt 4-Way parts are on the right.    Also, you will have to mill off the selector stops on your lower receiver so that the selector can rotate 360 degrees. You can see the missing stops in the picture below of an actual Colt M4 Enhanced Carbine with the 4-Way parts installed.  |
Yeah, there's nothing as much fun as taking a milling machine to a $13k gun. When you're done, the value will be $11.5k. Reminds me how how my last home improvement project affected my home's appraised value.  Yeah, I know, I know. I have got to stop beating this horse. And FWIW, I have seen a 4-way where the owner sent the selector to a machinist who welded new metal onto the outside of the selector arm, then milled away the inside so it would clear the existing stops. Then the metal guy reshaped the new arm and refinished it. Only cost a couple hundred more $$$, which is prolly better than chopping a factory Colt transferable receiver. With the cost of the kit plus the cost of the mods, he had about $700 in it. |
So I take it you just slide the torque spring into the burst cam and then attach it to the hammer? Is there a specific way the torque spring goes in to the burst cam, or can you just put it in any which way and it will work? [ADDED] So I am looking at the manual from the link above and it says "Cam clutch spring should be assembled with bend to the inside." Am I correct to assume that the "bend" in this case is the little piece of the spring that sticks out on one side? From the picture it looks like there is a slot in the burst cam that this little piece of the spring that sticks out can fit in to? Sorry for the noobie questions. I'm sure all of you have installed/uninstalled burst before and this seems like common sense!  I'm sure I'll feel the same way about it as everyone else that burst sucks, however I would like to be able to say that I have had actual expereince with it and I know how to install and uninstall one. Thanks a lot! |
Clutch spring - OK, I never knew what it was officially called. There's a small slot in the burst cam for that little leg that sticks out. The spring will only go on one way with the little leg on the bottom, snugging down to the bottom of that slot. It can take a little effort to wiggle the clutch spring down onto the hammer. I usually assemble burst cams by putting the spring in the cam, covering the top with my thumb to hold it in there as I press/wiggle it onto the hammer. |
Cool! Thanks everyone for replying to my thread. I feel much more enlightened now!
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I personally think the burst setting (even with it's inherant flaws) has some value added....and I especially like the Colt M4E. BUT For someone to install one of those humpty dumpty aftermarket kits in their transferable M16 or be foolish enough to mill a transferable receiver to properly accept the OEM Colt 4 way FCG....naaaaa. |
I've got a colt 4 position w/ my RDIAS so the receiver stops were not an issue, but if someone had a registered receiver they could just mill the selector to clear the stops. |
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I am also planning to install a Colt 4-postion selector into a Colt M16 RR. As discussed, the Colt selector lever will not clear the receiver selector stops. Other than machining off the receiver selector stops, does anyone have any suggestions on how to modify the selector itself? The colt lever/knob is too thin to facilitate clearance machining as suggested by Jerad. I was considering cutting off the lever and using epoxy adhesive (e.g., JB Weld) to attach a new lever that would clear the stops. I am reluctant to weld the new lever since this could effect the mechanical properties of the selector shaft (warping, heat treatment, etc.). Does anyone know how the Colt M4 receivers, which came with this selector, are configured? Any thoughts on the JB Weld? Anyone have any further suggestions? Thanks. |
JJ, Colt mills the selector stops off of the lower receiver on the M4E which facilitates the selector being able to rotate 360 deg clockwise and counter clockwise...if you scroll up there is a picture of the lower. It's a pretty slick setup that I do believe was done at the request of Naval Specwar. I know, I know...what hasn't been requested by those squids. Anyhow, Bob Gaw had one on loan from Colt when I went through the Armorers course and that was the only one I've ever seen/finger fucked etc. It had a 10.5" M4 Commando Upper on it....SWEET!!! Yes...I did fantasize about sneaking out with it for a split second |
I don't know of anyone that makes a 4 position ambi selector. A 3 position M16 ambi selector would not work with the 4 way parts. |
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