Posted: 9/4/2002 5:06:54 PM EDT
| What is the big deal with the open bolt guns like the Mac's. I read that they shoot fullauto with no modifications. If there are no modifications then how do they shot fullauto? I have never owned onejust curious. |
|
Most open bolt weapons have a fixet firing pin. when the bolt closes, it fires. Basically the force of the bolt closing pops the primer. On an m-60 the firing pin is fixed, but doesn't contact the primer until the locking lugs are fully closed in the chamber. Other lower pressure cartridges can have a fixed pin with no lugs at all. There were some later WWII Thompsons that had nothing more than a nub of metal on the face of the bolt. Remember- NEVER ride the bolt forward on a round in an open bolt weapon! It will fire! So, what makes an open bolt weapon not full auto, is that something has to "catch" the bolt while it is to the rear. if it is not caught, it will go back forward and fire again. I Know nothing about Mac 10's but I believe the principle is the same-Slam fire basically. |
|
Did you hear that on the news? Just another wonderful lie to make people afraid of some particular type of gun. Any weapon made to be semi-auto needs some modification to make it full auto. Otherwise it would have been made a full auto weapon. There are real simple ways to make some full auto, but not controlable. That is you can make even a 1911 go full auto by putting in a longer firing pin. When you let the slide go forward, it will empty the gun. But you don't have any control over how it fires. It just empties the gun each time. The thing that catches the bolt/hammer each time you pull the trigger is the part that needs modification to make a weapon select fire. |
|
I own a registered Thompson that has a "nub" on the bolt. Known as the M1A1 and it was developed to make it cheaper for mass production. Takes a little getting used to when firing any open bolt gun. Also have a MAC which has a "nub" as well. Early semi auto MACs were open bolt. BATF forbid further manufacture saying they were too easy to convert to illegal FA. Those still around are legal but bring about the same price as registered FA. Wonder why? Don't even THINK about modifing one!! Any SELECT fire weapon, meaning selectable full or semi, has some form of disconnector so that when in SA mode it will fire only one shot per trigger pull. FA position disables that function so one pull does the whole mag if you like. The M60 I have worked on did not have a fixed firing pin. The op rod drove the firing pin forward after the bolt rotated into place. Can't imagine how one could have been made with a fixed pin. The M60 like the M-16, FAL, AK, Browning etc. fires from closed bolt. Uzi, MAC, M1A1 Thomson, MP40 CZ 24, Sten and others fire from open bolt. Simpler, fewer parts, cheaper, better barrel cooling. |
|
The pin on a 60 doesn't actually reciprocate like in a 16, fal etc. the bolt moves around the pin, but the pin is fixed. The bolt does lock and unlock from the chamber prior to firing, but that is the action of the bolt turning in the grove in the op rod. It does fire from an open bolt, though. The sear is in the grip, and is a simple lever that catches in the groove in the bottom of the op rod, perventing it from going forward. There is no hammer on a 60. I carried one for almost 3 years while in division, and was an assistant in the armory. The saw (M249) works in a very similar fashion. Open bolt is not necessarily cheaper or easier to produce. Remember the Blish lock on the 1st model thompsons? |
|
Here's the deal on RPB open bolt Macs. If you interupt the trigger disconnect they run full auto. Hypothetically if you put say a small refrigerator magnet about as thick as a .380 casing on the frame behind the trigger you would have a "temporary" full auto as long as you held the trigger down. Let it go and it stops. And of course once you remove the obstruction it is again semi auto. Rumor has it that a spent .22 casing taped behind the trigger of a .380 MAC11 produces the same results. Other open bolts, like the first UZI carbines were simple too, but not nearly as easy as Macs which is why ATF put a stop to them pretty quick. |
|
Quoted: What is the big deal with the open bolt guns like the Mac's. I read that they shoot fullauto with no modifications. If there are no modifications then how do they shot fullauto? I have never owned onejust curious. I've got an open bolt Mac that goes full auto all of the time. I have more fun with my Mac's than with my ARs. [;)] |
|
Quoted: Quoted: What is the big deal with the open bolt guns like the Mac's. I read that they shoot fullauto with no modifications. If there are no modifications then how do they shot fullauto? I have never owned onejust curious. I've got an open bolt Mac that goes full auto all of the time. I have more fun with my Mac's than with my ARs. [;)] IBTJBTTYA! (In before the Jack boot thugs take you away!) mug |
|
Actually, the M1928A1 and M1 Thompson guns had a separate firing pin in the bolt, but the firing pin was always in the forward position. Finally, about 1942, it dawned on somebody that they could just make an M1 Thompson with the projection milled onto the front of the bolt, and the M1A1 Thompson was born. M1 models refurbished after the war often had M1A1 bolts used, since they are interchangable with the M1. Re open bolt UZI carbines, I've never seen nor heard of one that came into the country that way. There were a couple of outfits that made up some open bolt replacements, with the slot in the side, to fit the semi only UZIs; but if IMI made up any that way, I suspect it would have been just a few demo types to see if ATTF would approve them. The first MAC10's and 11's were ridiculously easy to convert. Full auto only was accomplished as noted above. Select fire could be had by cutting out the "package" trigger/ sear assy, replacing w/ select fire parts , drilling a hole in the side of the reciever and installing the selector lever. Of course, this was back when you could legally "manufacture" a machine gun by paying the tax. I know several guys who did it. RPB wouild sell you the parts no questions asked. (Edited to add) Let me be clear. The people I knew who did the conversions did so legally, after paying the tax. |