View Full Version : 3RD Burst vs. Full Auto
Do you need to have the same modifications done to a lower reciever to obtain 3 round burst as full-auto? Does it have the same legal implications? I find a lot of info on DIAS's but I'm not looking to go full auto and I can't find much info on 3 round burst.
:) well moosepn, m4carbine.com has been such a big help to me, as a member let us see if i can help you. yes if it is auto compatible(i.e. w/hole for automatic sear pin), no block over safety and mil,standard fire control pins. yes, same legal definition as machine gun, the three round bust consist only of a few more parts. if you can get your hands on USMC TM 05538C-23&P/2 it will give you all the info to see and understand the parts and there relationship to burst fire. it seems that you would need an M16 Carrier,automatic sear and its pin,compatible M16 hammer,burst cam,cam clutch, M16 safety lever and auto M16 disconnecter's. please don't think that i am an expert, as i am only looking at the USMC TM.i am confidant that other members more knowledgeable than me will also step in to help answer you questions. i will also continue to follow this thread in the event that my info is not correct. good luck. Don............
I like the 3 rd burst.that is what i used at ft knox .after the first 3 rds you are shooting sky or over their head.its better to control your shots.with a burst even on the 240 bravo and saw 249 short 7 -9 sec burst. full auto is fun but if you are not using it right you are just dumping ammo.I would rather control my shots make them count.plus if you need to,a quick 10 pulls of the trigger dumps the mag.I like the tri-burst
Now if you own a NFA M-16 with full auto you can put a tri-burst in fine.with no extra paper work.But using a tri-burst is a Machine gun so all the wonderful BATF and NFA laws apply:(
A weapon capable of firing more than once with a single press of the trigger is a machine gun... As a private citizen you need to follow the procedures of the BATFE and your local government outlined for the purchase of any NFA weapon... If you are in a machine gun friendly state, this can be a relatively straightforward procedure, if not you are SOL...
Buck
The legal inplications is if you dont have a 15k priced preban 86 lower it is going to send you to the Federal Pen.
Do you need to have the same modifications done to a lower reciever to obtain 3 round burst as full-auto? Does it have the same legal implications? I find a lot of info on DIAS's but I'm not looking to go full auto and I can't find much info on 3 round burst.
Short answer your question YES- "you need to have the same modifications done to a lower receiver to obtain 3 round burst as full-auto"
You need a sear. .. whether that sear is a standard military sear (which would require the receiver being registered as a machinegun) or a LL (Lightning Link) sear or a DIAS (Drop in Auto Sear). Both the LL and DIAS are considered the registered NFA machine gun.
Given that the gun has a sear the only difference between a full auto gun and a 3 burst gun is the chosen trigger group.
That sucks, but it makes sense in a communist kind of way. I'm not sure how to word this exactly but if you put a trigger group used for 3 round burst(hammer, disconnector, etc.) into a non modified lower, would it still fire single shot and just not be able to switch over into 3 round burst? Would that even be possible with out having a hole drilled into the lower?
If you understand the M16/ AR system one will understand that the "sear" does not actually make the weapon fire full-auto or burst, it only regulates it. There is another item that is needed in addition to the hammer, trigger, and disconnector.
twodollarbill
02-23-08, 09:08
Without the sear...the hammer disconnects too early and rides the bottom of the BCG.
It was my understanding that the "Burst" option was introduced so that the
weapon would now control the amount going down range.
Finger taps are no longer needed.
We are too stupid to learn proper techniques.....RIGHT!!!!
http://i246.photobucket.com/albums/gg117/twodollarbill/DSC02187.jpg
http://i246.photobucket.com/albums/gg117/twodollarbill/2.jpg
Without the sear...the hammer disconnects too early and rides the bottom of the BCG.
But the rifle will still fire fully automatic. It may or may not stop with the hammer down. I've seen this first hand on days where guys I know fire some full auto throughout the day only to realize that they didn't even have their RDIAS in the lower.
As stated above... the sear regulates the hammer drops.
I SNAFU'ed my post. I guess what I should have said is that if you had all the items from a full or 3rd burst gun (including the overlooked piece) and the correct BCG you could make the weapon fire more than 1 round at a time. IIRC, that is why some people were cautioning others to be careful of what parts they had installed in their guns because accident or not the BATFE may not be so forgiving or understanding.
I wouldn't say I "understand" completely how 3 round burst works. I understand that there is a difference in the design of the lower reciever as far as where the hammer, trigger and disconnecter fit into. In addition I think the bolt carrier is shaped differently and there is an additional spring and control that fit over the hammer assembly as m700m said.
So if I understand twodollarbill correctly, if I installed the lower parts of an M16 without drilling the hole for the sear and its pin, or using a DIAS the hammer would disconnect too early and effectively do nothing? Or would it fire a single shot disconnect too early than reset. I realize that might not even make sense. I'm trying to figure this out
Failure2Stop
02-23-08, 11:07
Without an auto-sear or DIAS the hammer will not be retained properly as the BCG moves forward. It may fire, it may not. It may fire the entire contents of the magazine or it may fail to fire on the second shot. The hammer will be chasing the bolt carrier and may or may not exert enough pressure on the firing pin to sufficiently dent the primer.
It doesn't have to be a reliable machine gun to get you thrown in jail though, it just has to do it twice- once to get you reported, and once again in the ATF lab.
Basically the one component that is overlooked is ensuring that you also have a full-auto (select-fire) selector lever. I don't recommend that you install these parts, but if you did you may be surprised as to what happens.
twodollarbill
02-23-08, 22:01
I wouldn't say I "understand" completely how 3 round burst works. I understand that there is a difference in the design of the lower reciever as far as where the hammer, trigger and disconnecter fit into. In addition I think the bolt carrier is shaped differently and there is an additional spring and control that fit over the hammer assembly as m700m said.
So if I understand twodollarbill correctly, if I installed the lower parts of an M16 without drilling the hole for the sear and its pin, or using a DIAS the hammer would disconnect too early and effectively do nothing? Or would it fire a single shot disconnect too early than reset. I realize that might not even make sense. I'm trying to figure this out
There is a notched cam on the hammer pin that counts (or follows) the hammer strikes. There is a
second disconnect that extends and rides the cam and trips at the 4th count. The counting sequence
soes not reset to zero when you stop or empty a mag. You may start with a one or two round burst, then three, three, three....
Hope the Pics help
http://i246.photobucket.com/albums/gg117/twodollarbill/DSC02228.jpg
http://i246.photobucket.com/albums/gg117/twodollarbill/DSC02226.jpg
But the rifle will still fire fully automatic. It may or may not stop with the hammer down. I've seen this first hand on days where guys I know fire some full auto throughout the day only to realize that they didn't even have their RDIAS in the lower.
As stated above... the sear regulates the hammer drops.
i was under the impression that removing the disconnector from a semi AR15 lower would result in a single shot followed by the hammer jamming the bolt shut on the next round resulting in a costly lecture from your gunsmith.
so you're saying that you can fire full auto without a registered auto sear? :confused:
disclaimer-for educational purposes only.. i have ZERO intentions of creating a machine gun or any other illegal weapon.
I also have no intention of illegally making a machine gun. It may be possible.
Army Chief
02-26-08, 04:39
Most any semi-automatic firearm can be altered to fire in something approximating a fully-automatic mode, but the issue is whether or not that is operator-controlled (i.e. whether or not the rate of fire is being directly influenced and regulated by the trigger or fire control system).
The ad hoc solutions being discussed here will not create a select-fire weapon, but may well result in a "runaway" weapon wherein a single trigger manipulation will send the gun into an uncontrolled firing cycle that will continue until (a) the weapon depletes the contents of the feeding device, or (b) the weapon malfunctions. That may look/feel like full auto fire for a few seconds, but in functional terms it is really nothing of the sort.
Aside from the obvious danger and recklessness associated with deliberately inducing a malfunction of this sort, NFA restrictions also come back into play here, as a single trigger activation is resulting in an automatic (if uncontrolled) mode of fire. In other words, bad idea.
Chief
Full Auto and Burst are not worth the price of admission to the club, the registered guns are outrageously expensive to buy, require governments hoops to be jumped through and waste ammo at an accelerated rate.
I fire FA and burst on Uncle Scrooges dime, for me well placed semi fire is better.
To the OP:
and old M16A1 that is FA, may with the fire control parts for the 3 rd burst be converted to fire burst, similarly the M16A2 with standard A1 fire control parts will fire full auto. If the lower is drilled for the auto sear it will be capable of being configured either way.
The RDIAS still required the FA fire control group and selector to work.
I am a little confused. Both the M16A2 and M16A1 have sears and they are identical. The difference between them firing burst or auto has to to do with the Fire Control System. As a matter of fact I have seen a few "units" that replaced their 3 rd. burst w/ auto FCS.
Full Auto and Burst are not worth the price of admission to the club, the registered guns are outrageously expensive to buy, require governments hoops to be jumped through and waste ammo at an accelerated rate.
I fire FA and burst on Uncle Scrooges dime, for me well placed semi fire is better.
To the OP:
and old M16A1 that is FA, may with the fire control parts for the 3 rd burst be converted to fire burst, similarly the M16A2 with standard A1 fire control parts will fire full auto. If the lower is drilled for the auto sear it will be capable of being configured either way.
The RDIAS still required the FA fire control group and selector to work.
Army Chief
02-27-08, 05:55
Both the M16A2 and M16A1 have sears and they are identical. The difference between them firing burst or auto has to to do with the Fire Control System.
True statements. I'm not sure where the confusion may be setting in here, but if the weapon is drilled for the sear, then the question of burst versus full-auto simply boils down to what parts reside in the lower of that particular model/generation/specification.
Chief
Alaskapopo
03-08-08, 17:33
I like the 3 rd burst.that is what i used at ft knox .after the first 3 rds you are shooting sky or over their head.its better to control your shots.with a burst even on the 240 bravo and saw 249 short 7 -9 sec burst. full auto is fun but if you are not using it right you are just dumping ammo.I would rather control my shots make them count.plus if you need to,a quick 10 pulls of the trigger dumps the mag.I like the tri-burst
Now if you own a NFA M-16 with full auto you can put a tri-burst in fine.with no extra paper work.But using a tri-burst is a Machine gun so all the wonderful BATF and NFA laws apply:(
I don't like the 3 round burst for a few reasons. For starters it messes with your semi auto trigger pull. You get two lighter pulls and one heavy one. Second the cam is always counting. So if you fire a few rounds in semi your first burst will not be 3 rounds it will be 1 or 2 or maybe three if you are lucky.
Full auto is far better. Your finger is your burst control. You should be able to control easily the amount of ammo you deliver with just your finger. Rather thats 2 to 4 rounds.
Pat
I never really notice a differents in the trigger pull but yes the cam is always counting the first burst can be off.their are some 4 position kits that give you a burst and full auto too.but i have never fired one.good points though:)
Alaskapopo
03-08-08, 19:07
I never really notice a differents in the trigger pull but yes the cam is always counting the first burst can be off.their are some 4 position kits that give you a burst and full auto too.but i have never fired one.good points though:)
There is two dis connectors in the burst guns and every third shot you have to release both dis connectors to fire the shot. That is why you have the heavier trigger pull every third round. I simply prefer fixing training problems with more training vs simply throwing equipment at the problem.
Pat
3rd Burst in the M16FOW is TERRIBLE -- it ruisn the semi trigger pull to a disgusting point.
I've never need Auto ever operationally - but I'd much rather have the auto ability - and have a good semi-auto pull.
The Army tried to instill a mechanical system where the issue was training.
KevinB
3rd Burst in the M16FOW is TERRIBLE -- it ruisn the semi trigger pull to a disgusting point.
You can say that again..... The trigger on a A2 is awful....
Three rd burst is a waste in my Opinion.
and Auto has special applications that are very narrow in scope.
Kevin,
You are correct. They put a mechanical device in the weapon rather than train personnel proper shooting and when to use accurate aimed fire or full-auto fire. I can see FA for room clearing, breaking contact on a near ambush or suppressing the hordes as they come across the wire, other than that it should be one shot, one kill.
25M death is ridiclous as well. I can understand in some situations due to range or time limitations, but larger bases should have better ranges and they should run hard.
3rd Burst in the M16FOW is TERRIBLE -- it ruisn the semi trigger pull to a disgusting point.
I've never need Auto ever operationally - but I'd much rather have the auto ability - and have a good semi-auto pull.
The Army tried to instill a mechanical system where the issue was training.
I've noticed I can controll longer F/A burst -- some Brit 22 guys where showing us that years ago with their M16A1's - and I thought they where crazy -- but now at almsot 38 and 215lbs plus 45+ of gear - I can see that its a lot easier than I though those many year and pounds ago.
When we'd go South and shoot against people in competitions some of the convetional mil guys they'd start thinking short barrels where a hinderance - and they quickly learned their trigger was the biggest hinderance on the weapon. I'd say dont worry not even I can make an A2 shoot good :D
Alaskapopo
03-09-08, 09:51
Kevin,
You are correct. They put a mechanical device in the weapon rather than train personnel proper shooting and when to use accurate aimed fire or full-auto fire. I can see FA for room clearing, breaking contact on a near ambush or suppressing the hordes as they come across the wire, other than that it should be one shot, one kill.
25M death is ridiclous as well. I can understand in some situations due to range or time limitations, but larger bases should have better ranges and they should run hard.
I have always been taught that you never shoot just once. We train that if someone is worth shooting once they are worth shooting twice and sometimes more.
Pat
I simply prefer fixing training problems with more training vs simply throwing equipment at the problem.
Pat
very good point ,when did the army start using 3 burst early 80's?I know the training I got was things i already knew. it really blew my mind that so many people that Got to BRM never had held a rifle.95% of what we did was on semi-auto,the trigger pull never really bothered me.Most of the ranges we used out to 300 meters ,I was able to use the M4 very well.when we did use the tri-burst during convoy live fire,Red dot optics,Night time with the lazer and Night Vision.the younger ones would "Rambo" it and not take controled aimed shots .I felt with the BRM the army could have been a little more up to speed.
But like I am told the" tri-burst is to save ammo".with a good trained soldier full auto would be perfect ,like with the saw and 240 4-9 second burst very effective.But with the Troops i have seen and I am sure the people here have seen it too, some of the soldiers could not use a full auto .They are just not trained well enough on the weapons ,they would dump a mag and hit nothing .army's thinking make it go 3 shots will cause the soldier to aim the shots,Not by what I saw ,
But who am I to question the ARMY:) .it is more parts but if you never really shot to that degree before,the harder stiff pull in semi to me is just not that big of a deal.I still can make it do what I need to save my ass.I have owned Ak-47 type weapons since the 80's so the pull of that stiff trigger in my M4 still was a step up from the AK ,I was so use to blasting away with.But again the M4A1 is still Full auto.But I never saw any of those it was all M4 A3 tri-burst.
But can you fire a full auto M4 and hit a center mass just as good as the tri-burst.with out shooting sky?I only shot the 249 saw and 240 bravo and mk-19 ,50 cal in full .with the saw deployed in your fire team why do you need to lay down that volume of fire from the stardard rifle?does it not turn the soldier into more of a rifleman instead of a machine gunner?:confused:
I have always been taught that you never shoot just once. We train that if someone is worth shooting once they are worth shooting twice and sometimes more.
Pat
+1, two in the chest !that is what was drilled into my head.I even double tap my handgun now:)
I was paraphrasing. Obviously one shot will not always solve the problem and generally speaking I do double taps as the rule.
I have always been taught that you never shoot just once. We train that if someone is worth shooting once they are worth shooting twice and sometimes more.
Pat
I am a little confused. Both the M16A2 and M16A1 have sears and they are identical. The difference between them firing burst or auto has to to do with the Fire Control System. As a matter of fact I have seen a few "units" that replaced their 3 rd. burst w/ auto FCS.
I have seen units that had M16A1's that had been retrofitted with A2 stocks, A2 handguards, and 3-rd burst fire control components.
My point was regardless of what FCS is in the lower or what is stamped on the lower, the sear is identical in a 3rd burst and auto-gun. I also had a burst gun M16A2, that I converted to auto and into the A4 configuration.
I have seen units that had M16A1's that had been retrofitted with A2 stocks, A2 handguards, and 3-rd burst fire control components.
My point was regardless of what FCS is in the lower or what is stamped on the lower, the sear is identical in a 3rd burst and auto-gun. I also had a burst gun M16A2, that I converted to auto and into the A4 configuration.
I know, I was just chiming in. :p
Parabellum9x19mm
03-22-08, 14:28
I trained alongside a ARNG combat engineering unit in Ft. Lewis. i forget what state they were from, but these guys had A2s, with some weird plate under the pistol grip, which blocked the selector from going to the burst position.
talk about reluctance to solve a training problem. wtf?
I trained alongside a ARNG combat engineering unit in Ft. Lewis. i forget what state they were from, but these guys had A2s, with some weird plate under the pistol grip, which blocked the selector from going to the burst position.
talk about reluctance to solve a training problem. wtf?I believe that is a restrictor that is suppose to be installed due to civil unrest and the military is not suppose to carry full auto in to the public but this was not the case in when they went into downtown Katrina -ville.that part is talked about in the Technical manual for the M-16
Parabellum9x19mm
03-22-08, 14:41
very good to know. tks.
Heavy Metal
03-22-08, 14:57
3 rnd burst is a crutch.
Im new to the site and would like to know which states are "Auto" friendly. Is GA one of them?
Im new to the site and would like to know which states are "Auto" friendly. Is GA one of them?
https://www.m4carbine.net/showthread.php?t=11675&highlight=states
If you understand the M16/ AR system one will understand that the "sear" does not actually make the weapon fire full-auto or burst, it only regulates it. There is another item that is needed in addition to the hammer, trigger, and disconnector.
Im assuming you are talking about the bolt carrier? Or perhaps a shrouded firing pin?
While I do understand how the FA carrier is required to correctly operate with the auto-sear to provide full-auto fire, I've read different things about the shrouded firing pin. It appears that only full auto carriers shroud the firing pin. But this shroud seems like a good idea for semi-only action as it protects the firing-pin and firing-pin's pin. So does this shroud play any part in fullauto fire?
Robb Jensen
03-26-08, 07:51
Im assuming you are talking about the bolt carrier? Or perhaps a shrouded firing pin?
While I do understand how the FA carrier is required to correctly operate with the auto-sear to provide full-auto fire, I've read different things about the shrouded firing pin. It appears that only full auto carriers shroud the firing pin. But this shroud seems like a good idea for semi-only action as it protects the firing-pin and firing-pin's pin. So does this shroud play any part in fullauto fire?
Almost all companies making new AR15 semi auto carriers now have shrouded firing pins.
It appears that only full auto carriers shroud the firing pin.
I've seen COLT semi carriers with the shroud.
so all the stuff I've read about the shroud being needed for correct full-auto action is incorrect?
I'm thinking about signing up for the colt armorers course coming up in Miss.
Robb Jensen
03-27-08, 07:37
so all the stuff I've read about the shroud being needed for correct full-auto action is incorrect?
I'm thinking about signing up for the colt armorers course coming up in Miss.
Incorrect...Yes. The firing pin shrouded has nothing to do with auto. It'll work as a full auto carrier whether or not the firing pin is shrouded so long as the tail end of the carrier is full length like a typical full auto carrier. It works best as a shrouded carrier because by design it should be the carrier cocking the hammer and not the firing pin.
Here is a shrouded semi-auto carrier. (it's either a new RRA or Bushmaster carrier)
http://img.photobucket.com/albums/v408/gotm4/bad5e060.jpg
Here is a shrouded Colt semi-auto 1/2 circle carrier.
http://img.photobucket.com/albums/v408/gotm4/handguardwrail007.jpg
Here is a unshrouded Colt semi-auto 1/2 circle carrier.
http://img.photobucket.com/albums/v408/gotm4/handguardwrail008.jpg
Left to Right (unshrouded semi carrier, shrouded RRA 'enhanced' carrier, Colt M16 carrier).
http://img.photobucket.com/albums/v408/gotm4/carriers.jpg
The shroud actually helps allow the gun to fire in full auto in the absence of an auto sear, but in a real set up does nothing more than Gotm4 said. This is probably what that guy who got convicted with the OLY arms and M16A2 parts kit had going on.
The shrouded design is the correct design. The ramped design allows the AR style firing pin collar to snag on the notch in the ARs hammer in the event of a failure of the hammer to remain cocked after cycling a spent casing out. (thus, jamming the gun up and preventing a burst fire of any kind)
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