The problem is more in accepting what it says. It's really not that confusing.
The NFA says a rifle is " a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder". That's a very broad definition. The official definition of a rifle in the NFA does not say a rifle has a shoulder stock, nor does it define what a shoulder stock is. The only mention of a gun stock in the NFA refers to the grip of a pistol.
Here's a simple thought experiment.
Question 1. If one holds a rifle exactly as they would normally hold and shoot it, with the sole exception of holding it away from their shoulder so that the stock doesn't make contact with the shoulder, does the weapon cease to be a rifle under the NFA definition?
Question 2. If one holds an AR pistol with any sort of rearward projection exactly as they would normally hold and shoot a rifle, with the sole exception of holding the rearward protection away from their shoulder so that it doesn't make contact with the shoulder, what makes it different from the rifle in Question 1?
For years, everyone was happy with the simple interpretation that you made an SBR out of a pistol when you added a shoulder stock.
Then came "pistols" (e.g. AR and AK pistols) that are basically rifles with short barrels and no stocks. Not a problem because everyone knew what a shoulder stock was and these guns didn't have them.
Then came rearward projections for such guns that weren't called stocks and now suddenly it was no longer clear if these pistols had shoulder stocks or not--or even what was a shoulder stock and what wasn't. Maybe the problem can be solved by looking at the law--but remember there's no definition for shoulder stock in the NFA and besides, the presence of a shoulder stock isn't explicitly required for a firearm to be a rifle under the NFA.
If it was your job to straighten out the resulting confusion, using the definitions and text of the NFA as a basis to distinguish between an AR SBR and an AR pistol, how would you do it? Could you do it?
The NFA says a rifle is " a weapon designed or redesigned, made or remade, and intended to be fired from the shoulder". That's a very broad definition. The official definition of a rifle in the NFA does not say a rifle has a shoulder stock, nor does it define what a shoulder stock is. The only mention of a gun stock in the NFA refers to the grip of a pistol.
Here's a simple thought experiment.
Question 1. If one holds a rifle exactly as they would normally hold and shoot it, with the sole exception of holding it away from their shoulder so that the stock doesn't make contact with the shoulder, does the weapon cease to be a rifle under the NFA definition?
Question 2. If one holds an AR pistol with any sort of rearward projection exactly as they would normally hold and shoot a rifle, with the sole exception of holding the rearward protection away from their shoulder so that it doesn't make contact with the shoulder, what makes it different from the rifle in Question 1?
For years, everyone was happy with the simple interpretation that you made an SBR out of a pistol when you added a shoulder stock.
Then came "pistols" (e.g. AR and AK pistols) that are basically rifles with short barrels and no stocks. Not a problem because everyone knew what a shoulder stock was and these guns didn't have them.
Then came rearward projections for such guns that weren't called stocks and now suddenly it was no longer clear if these pistols had shoulder stocks or not--or even what was a shoulder stock and what wasn't. Maybe the problem can be solved by looking at the law--but remember there's no definition for shoulder stock in the NFA and besides, the presence of a shoulder stock isn't explicitly required for a firearm to be a rifle under the NFA.
If it was your job to straighten out the resulting confusion, using the definitions and text of the NFA as a basis to distinguish between an AR SBR and an AR pistol, how would you do it? Could you do it?