The Czar assumes that for every paragraph he writes, he loses 50% of his readership. In other words, the shorter the essay, the better. There are days he writes so many paragraphs that by the last one, he’s the only one reading it.

So it was with some caution that the Czar wrote his overly short piece on the AR-15 rifle. Fact is, one could write hundreds of pages on this marvelous rifle. Hence, the initial shock was that the first email he received was complimentary, rather than corrective. “Czar, you spent not time explaining the whole direct impingement versus piston driven design argument so irritatingly common to gun forums.” That’s what we expected.

The secondary shock was that this complimentary email was beautifully written by an operative that the Czar suspects with whom we have not previously chatted. The Czar is loathe to show anything but disdain, but holy crap we could use an Island Dweller-style essay on any topic from this guy. Please write in on any topic you wish, good sir.

Царь и Великий князь всея Московия,

Whilst sitting beneath an apple tree, I had a cat-like being phase in from elswhen and slap me across the face with a herring which contained your latest missive. Reflecting on the gravity of the situation I absconded with an apple and left you the following carved into the headstone of the Arcadian Shepherds: Unlike the number of licks it takes to get to the tootsie roll center of a tootsie pop, which only Mr Owl and GhettoPuter know (the former through wisdom, the later via brute force). It is very possible to know when an AR-15 stops being an AR-15, or even the same AR-15. Only the lower receiver is actually the AR-15 as it carries the serial number. All other parts do not even require a background check to purchase new. I would make a longer reply, but my Ship of Theseus is departing shortly and I need to figure out which one I am actually booked on.

Operative RKB

Look, if you aren’t a gun person, this post is not really for you. Move on: Dr J. will have some cartoon pony thing for you to gush over.

If you are, check this out.

The federal government defines the regulations that make up specific firearm purchases. For nearly every conceivable rifle, that’s the part of the rifle that contains the bolt. The bolt is the portion of the rifle that pretty much does all the work. When you load a rifle, the bolt pushes the cartridge into place. When you pull the trigger, the bolt is forced backward by the explosive force of the bullet going off, throws out the empty casing, pushes back on the recoil spring, and then leaps forward to load the next bullet. The bolt is pretty much it. As such, federal regulations make the bolt the most important part of the gun. Good luck buying a new bolt without answering some questions on a form and writing down a whole bunch of numbers.

On an AR-15, the body of the gun can be divided easily into two pieces: the upper receiver, which holds the bolt, the charging handle (that thing that loads the first bullet into the chamber), the bolt catch and other gadgetry, and the lower receiver, which holds the magazine and the trigger group. In the AR-15 rifle, federal regulations say it’s the lower receiver, not the upper, that causes all the trouble. As RKB says, the lower receiver contains all the numbers you would need to fill out on a form.

But the lower receiver is not immutable on an AR-15, either. In fact, many, many AR-15 owners change out pretty much all of it.

This is what the “lower receiver” on an AR-15 looks like. Legally, this is the AR-15 rifle, as RKB points out. But guess what? You can change this legally with no problem as well.

If you were converting your typical .223 (5.56x45mm, if you are one of us) rifle to a bigger 7.62mm bullet, you cannot use the standard AR-15. You are using a bigger bullet; this means you need a bigger magazine.

If you have a bigger magazine, you need a bigger magazine well. So the lower receiver has to be modified. And since you are using a bigger magazine well, you need a bigger breech (the breech is the part of the gun that holds the bullet in place before firing). If you have a bigger breech, you need a different bolt.

So this means if you are like the thousands of AR-15 owners who go from a .223 up to a 7.62mm, or go down to a .22LR, you need a completely different lower receiver and upper receiver. Bottom line—thousands of folks change their lower receivers.

The Czar was at a local gun show last Sunday; numerous vendors were selling brand new lower receivers with a variety of options and styles. Some folks were selling lower receivers for different calibers; others were selling lower receivers made with different materials.

Now, RKB is not incorrect: in fact, he is completely correct. If you are buying or selling a serialized lower receiver, you need to go through the legal paperwork.

But you are well within your legal rights to purchase an unregistered lower receiver, provided the lower receiver does not have an existing serial number. No serial number is required provided you don’t resell or give the receiver away. There is in fact a whole after-market in “unfinished” lower receivers.

An unfinished lower receiver is about 80% complete in terms of manufacturing. To finish it, you need to do some drilling with a basic drill press. The Czar has never done this, and cannot testify as to its ease or complexity, but a lot of folks do it with stuff around the house, so it cannot be too difficult.

Check out this video which explains the parts of an AR-15 and describes why you can change the lower receiver without problems. And it explains RKB’s letter in detail.

So again: if you can change this part out, too, when does your AR-15 really become something else? Whenever the hell you want. And this is the beauty of it. Heck, the Czar wants to take RKB out for some rifle shooting as soon as possible. Wouldn’t that be fun?