AR Question

[Couzer]

So I have noticed that a stripped AR lower will state that the caliber is multi? Does this mean that my other AR that says 556 only can be used for 556 and .223? I know it will mount up to any AR-15 platform, but is there a law that you can not switch a 556 lower to another upper that is a different caliber?

 

I am not very knowledgeable in this department.

[123456]

No law stating that you can not shoot 223 out of a 5.56. Lower really means nothing as far as difference in 223 and 5.56. It's all in the upper, if it can handle the pressures of 5.56.

[muledeerarea33?]

The chamber is what determines your caliber, a tight .223 chamber will stick some 5.56 cartridges, some won't. It all depends on what chambering you have in your barrel. The ar-15 platform will shoot several calibers, the markings on the lower don't mean much, as long as a round will fit the mag well and your chambered for that particular round, you can shoot it. There is no law, that I know of that will prevent a caliber change. If you have a lower marked SBR (short barreled rifle) and have the tax stamp for it, then there's stipulations on what parts your allowed to have in your home. But bottom line is, if it'll fit the mag well and your chambered for it, you can shoot it.

[Couzer]

Sorry after reading what I wrote, I confused myself on the question that I was wanting to ask. Why wouldn't manufactures just put multi on their lowers instead of specific caliber?

[galiuro mountain man]

There are no laws that state that you can not put a different caliber upper on a lower marked .223 or 5.56.

 

On another note, it is just an old wives tale that 5.56 and .223 are different. If there was a difference in pressures then the 5.56 round would be made to not fit in a .223. Also if it blew up guns there would be a ton of lawsuits filed. It is just like 7.62x51 and .308, no difference at all in the round but the 7.62 shows a higher pressure, this is because of how and where pressures are obtained in military pressure barrels vs. saami pressure barrels.

 

The only real difference is that the 5.56 has a touch more powder than a factory .223 load. It made this way for max velocity, not accuracy. .223 is normally more accurate than ball ammo.

[ShutYourLib]

There are no laws that state that you can not put a different caliber upper on a lower marked .223 or 5.56.

 

On another note, it is just an old wives tale that 5.56 and .223 are different. If there was a difference in pressures then the 5.56 round would be made to not fit in a .223. Also if it blew up guns there would be a ton of lawsuits filed. It is just like 7.62x51 and .308, no difference at all in the round but the 7.62 shows a higher pressure, this is because of how and where pressures are obtained in military pressure barrels vs. saami pressure barrels.

 

Not sure I agree with that. From my understanding the cases are identical, but the actual chamber dimensions are different. If I remember correctly the 5.56 chamber has a longer throat to accommodate higher pressures. There are a lot of cartridges that will chamber in other caliber rifles, but not safe to shoot.

[galiuro mountain man]

Well then, heres the offer I make to anyone here, if you have a 223 and have 556 rounds pm me and I will give you my address so I can get rid of this dangerous ammo for you.

[muledeerarea33?]

I said "some" 5.56 cartridges will stick. My mini 14 will stick every 5.56 I have but .223 is fine. None of my ar's have Had any issues but some could, depending on the chamber. There isn't much if any difference between 5.56 and .223 (except pressure) when you think about differences in machining

[gauchoand]

223 wylde go with that never worry again.

 

And no it doesn't matter what upper you put ona lower.

My 556 is on a 6..5 Grendal lower.