It is nearly impossible to convert an AR15 to a full auto rifle. Here is why- since at least 1988 most if not all of the AR15 receivers have been made with a wee bit less milling done to the receiver right where the auto sear would "drop in". Also, the receivers need another hole drilled for the full auto pin to added to the receiver even IF there was room to "drop in" the full auto sear. Having the exact plans, a precision CAD mill, and the chemicals to anodize the receiver is not only very costly but having the knowledge to do that work is mind numbing. So no, it is not easy in the least bit. A person is better off paying the tax and spending $10,000-$20,000 on a registered full auto firearm.
The same goes for the AK variants we see on the market today. A person has to first get the receiver plans, get a mill, find a machinist, get the proper parts, and install them properly. It is no easy task and in many ways the AK's are more finicky when being tinkered with because the timing is even more important for the gas system of an AK to get correct and if the job is done by a shade tree gunsmith the odds of the AK being destroyed increases 10 fold. I'm not a gunsmith but I do know there is a timing issue that is present in the AK's that is not an issue in the AR's.
Either way it is HIGHLY complex and not worth it.
As far as "filing the firing pin down" legend goes, the only thing I am aware of is the old SKS trick and that is something I've seen in person (and it was done not on purpose). First, it has to be a Chinese SKS because all other countries that used the SKS's have "firing pin return springs" in their models. The firing pin in a Chinese SKS can get stuck in the forward position once a groove has been worn in to the pin where it penetrates through the bolt face and in to the chamber. This is cause by thousands and thousands of rounds being fired and the firing pin being of a harder/softer metal than the bolt. The firing pin gets wedged in the forward position. Essentially, the firing pin is always "active" and as soon as the bolt slams home a cartridge in the chamber the round is fired, no trigger pull is needed since the hammer does not need to be dropped. My friend who bought the Chinese SKS back in 92 or 93 has had this happen to him a couple of times, luckily he is prepared and when it fires on full auto there is usually only 4-5 rounds left in the rifle, he just holds on for the ride and lets the magazine empty out, after all we're talking about 1-2 seconds.
I've offered to repair it for him but he oddly declines.
In short, there are lots of BS out there about firearms that lives on in urban legends. I just read where the shooter in CT "maximized" his rifle to do the most damage. He taped together 2 mags "jungle style" so he could change mags very quickly (only idiots do that to AR mags), and the ammo he used was "deep penetrating frangible ammo".... yeah, you read right. I did a
after I read that. Folks, frangible ammo is designed to come apart upon impact and NOT penetrate deeply. An FMJ would penetrate far more deeper than frangible ammo. Either way a person shot at point blank range is going to be badly hurt or even killed (btw, not that it matters but does everyone know that the 5.56 NATO penetrates best at 200 yards and not point blank?). Again, this is what we get when "journalist" who know nothing about a subject report and in issue with an intent on creating drama. Anyone remember the Wincherster Black Talon pistol ammo "buzz saw effect" from about 15 years ago???
