Full auto ar 15 modification
Let's say for the sake of conversation that it is completely legal to build your own machine gun. I'm fully aware that it is NOT, but I'm curious about something. In a select fire m16, when the selector is on auto, the disconnect is blocked by the selector and the auto sear catches the hammer and keeps it from falling until the bolt carrier travels forward again. When you want to stop shooting, you release the trigger and the hammer is stopped by the sear on the trigger.
If you took a semi auto and eliminated the disconnect hook on the hammer (or trigger), this would achieve the same result. Without the auto sear to hold the hammer from falling, the hammer would ride along the bolt carrier with only the hammer spring pressure behind it as the bolt carrier traveled forward towards battery. Once the bolt carrier passed the hammer, the hammer would fall and strike the firing pin, fire, and cycle again in full auto until the trigger is released and the hammer is stopped by the sear on the trigger.
Again, for the sake of this conversation, we are ignoring the obvious law violations. If this was done, it would make the gun full auto only and I cannot see that it wouldn't work. From a manufacturing standpoint, why add the auto sear? It doesn't really seem necessary.
Relax, I'm not going to try it. I'm just curious and like to think about these types of things.
The only negatives I can think of is:
The loss of the semi auto option.
Possible increased wear on the bottom of the bolt carrier and top of hammer from the hammer pressing against it under spring pressure during cycling.
Possible increased wear on the trigger sear from the hammer slamming into it when trigger is released.
Seems to me that during manufacturing, the engineers could take these things into account and use materials accordingly to prolong and prevent wear.
Am I missing anything? It's not a crime to exercise the mind... Not yet anyways.
If you took a semi auto and eliminated the disconnect hook on the hammer (or trigger), this would achieve the same result. Without the auto sear to hold the hammer from falling, the hammer would ride along the bolt carrier with only the hammer spring pressure behind it as the bolt carrier traveled forward towards battery. Once the bolt carrier passed the hammer, the hammer would fall and strike the firing pin, fire, and cycle again in full auto until the trigger is released and the hammer is stopped by the sear on the trigger.
Again, for the sake of this conversation, we are ignoring the obvious law violations. If this was done, it would make the gun full auto only and I cannot see that it wouldn't work. From a manufacturing standpoint, why add the auto sear? It doesn't really seem necessary.
Relax, I'm not going to try it. I'm just curious and like to think about these types of things.
The only negatives I can think of is:
The loss of the semi auto option.
Possible increased wear on the bottom of the bolt carrier and top of hammer from the hammer pressing against it under spring pressure during cycling.
Possible increased wear on the trigger sear from the hammer slamming into it when trigger is released.
Seems to me that during manufacturing, the engineers could take these things into account and use materials accordingly to prolong and prevent wear.
Am I missing anything? It's not a crime to exercise the mind... Not yet anyways.
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I would guess that the hammer simply following the bolt home would not allow it to generate enough speed prior to hitting the firing pin, though I am not sufficiently curious to test the theory. 0 -
OK, this is not the forum, nor the place to be bringing this up, but from people I know in the LEGAL business of building for LE agencies, that does not work 99.9% of the time. The hammer riding the bolt carrier all the way back does NOT develop enough energy to strike the firing pin hard enough, to transfer sufficient energy to the primer for ignition.
However, getting caught with a weapon with this modification, is just cause enough to prove, by law, that whoever's(the person in possesion of the weapon, not the person who modified it) intentions were, to have a fully automatic, illegal weapon. That in turn is cause enough for a 10 year 1 on 1 personal relationship with bubba, and/or a hefty fine.
So, if you are in a state that does allow NFA weapons, it is best to save your pennies and do it the right way, as they are extremely expensive. A transferrable AR-15/M-16 willstart these days around $12,000.00. Yes that is correct, and they go up from there. If you are not in one of the states that allows NFA weapons, then you should refrain from this, as you have shown your cards publically.
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quote:But even if it was legal, and did work, I wouldn't do it just for the fact of the increased wear on the bolt carrier, hammer, and sear. Like I said, the slide fire stock is close enough for me.
These weapons were initially designed as a selective fire weapon. It would take 10's of thousands of rounds to wear out any of the parts you have listed. I am not sure what make you have, but unless the barrel is stainless steel, there is a greater chance of it being chrome plated than not.
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I have a slide fire stock. That's close enough for me. I was just thinking about this from a mechanical design point of view and it made me curious.
I didn't know about the modification being illegal even if it didn't work. That's interesting in another sort of way.
But even if it was legal, and did work, I wouldn't do it just for the fact of the increased wear on the bolt carrier, hammer, and sear. Like I said, the slide fire stock is close enough for me.
Even when I shoot with the stock "on" I let the gun completely cool between magazines so I don't kill my barrel. I have a lot of pride in my firearms and I take EXTREMELY good care of them.
But I'm taking them all on another boating adventure this weekend so....0 -
Whats the big taboo about TALKING about the mechanics of a FA versus a SA rifle. So what, talk about it all you want. Seems to me this IS THE FORUM for questions like that.
That said, What you describe is a condition called "hammer follow" or something like that, where the hammer rides the bolt carrier forward and strikes the firing pin as the action closes. This is very dangerous as it likely will cause an out of battery shot that can result in an exploding case.
The purpose of the auto sear is to delay the movement of the hammer until the bolt carrier is fully forward allowing the action to get fully into battery before the shot is fired.0 -
An M2 carbine, for instance, has a sear that performs both semi and full auto functions, as the sear trips the hammer during full auto.
In an M16, the sear is completely different, and is isolated from, the full auto engaging parts. So, when the hammer is in full auto mode, the hook retains the hammer, and the sear is a non-functioning part until the trigger is released.
Now, the 'following hammer' scenario of full-auto:
Colt tried to eliminate that aspect by changing the cocking ramp angle on the bottom of the carrier assembly, and placed a notch into the top of the hammer to jamb the firing pin into the hammer notch prior to the hammer fully falling.
Notice the different ramp angles to the ramps that cocks the hammer in both semi and full auto examples, (civillian setup on bottom-semi auto only) and the amount of firing pin protrusion on the semi-auto setup on the assembly. Hope I helped. Joe
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You guys rock! That's why I love this place. Great answers. Fast answers. And great explanations. (Usually[;)]) thanks again to everyone 0 -
I'm not knowledgeable enough to discuss the specifics, but I can say from general principles/common sense that if all you had to do to convert a regular AR-15 to a functional full-auto gun was to file a little metal off the hammer or trigger, then
a. This kind of illegal machine gun conversion would be trivially easy, and therefore incredibly common, and
b. The BATFE would have banned these guns years ago (as it did for ALL semi-autos that fire from an open bolt).
Since I know objectively that a and b are not true, I conclude that this sort of conversion simply doesn't work in the real world.0 -
you would convert a closed bolt gun to an open bolt gun, in other words gun would fre before bolt lugs engaged , very dangerous 0 -
I am told that if a bolt carrier with the covered firing pin is used, and if an early style hammer without the "catch notch" on it is used, and if the disconnector is removed, and if the cartridges are loaded with "soft" pistol primers, then such a combination will fire "full auto" reliably. But there is a tiny chance of such a configuration firing a bit out of battery. And such a configuration is ILLEGAL, no ifs, ands or buts about it.
The auto sear is necessary to hold the hammer until the bolt is just going into full lock up before releasing it, thus ensuring reliable and safe operation with regular military ammunition.0 -
Not even gonna comment cause a lot of people will cry to the hall monitors. 0
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