Researching for my first AR15 :)

[Boboclown]

You are aware, I hope, that the 5.56mm cartridge was originally designed to be shot in a 20 inch barrel?

The neat thing about time and technology is that they change. While originally they used M16s (referring to all variants), which have the 20 inch barrel, they have M4s which also uses the 5.56 cartridge. The M4 (referring to all variants), if I can remember correctly, has a 14.5 inch barrel (14 something anyways). The SR-25, which also uses the 5.56 cartridge, has an 18 inch barrel.

There's also the K2 rifle which is made in South Korea, 18 inch barrel I think. Wish I had one, it's a reliable rifle that also uses 5.56.

I'm sorry, is this all blasphemy? Do those of us who prefer shorter barrels, for whatever reason, need to repent from our "sins" and conform to using a 20 inch barrel? Not trying to be offensive, but just because the 5.56 was originally used by the M16, with a 20 inch barrel, doesn't mean it has to be used in a 20 inch barrel only. Shorter lengths are also valid for use. Unless I'm misreading what you said, if that's the case then you should work on wording.

Now to go on about barrel lengths... Even though this has probably been beat around the bush to hades and back.

The quality of the barrel would actually matter more than the length. If your 20 inch barrel is bubblegum, but the 16 inch barrel is of better quality, I'm sorry but that 16 inch barrel would still be better.

Downsides of shorter barrels: Drop in velocity and shorter sight radius. The drop in velocity is somewhat negligible. Hopefully that doesn't open up a can of worms, but if it does I apologize ahead of time.

Downsides of a longer barrel: More harmonics comes into play. You might think "oh only one downside? The longer barrel is better than!" However... I'll get to that later on in this post, you'll see.

Pros of a short barrel: Less barrel harmonics. Oh look it is coming to play here. Due to the shorter barrel having to deal with less barrel harmonics, it'll have more potential for accuracy than the longer barrel. The shorter barrel is also lighter and more compact.

Pros of a longer barrel: You get more velocity so there will be less bullet drop. The bullet will also have more energy behind it. Longer sight radius, which helps you actually aim when using iron sights since it allows you to see more errors than you could with a shorter sight radius. Though the use of optics makes this negligible, unless you have back up iron sights (which I recommend anyways).

This is providing that bother barrels are the same in everything but length.

Conclusion: Honestly, if you can't decide you can compromise and get an 18 inch barrel, or you know, get two uppers with a 20 inch barrel and whatever length you want for the other one. Ultimately it is up to the person to decide what they want.

Long post I know, I apologize.

 

[U8395279]

The neat thing about time and technology is that they change. .

Exactly. That is why new cartridges have been developed like the 6.8 SPC and 300 Blackout.

I'm sorry, is this all blasphemy?

It is, if you are in the Marine Corps. The Marines have bought very few M4, and still primarily rely on the M16A4 with 20 inch barrels.

Unless I'm misreading what you said, if that's the case then you should work on wording.

All I stated was a simple fact. A fact that you have not contested, BTW. You have simply gone off on discussing other tangential issues

Downsides of shorter barrels: Drop in velocity and shorter sight radius. The drop in velocity is somewhat negligible.

It is negligible if one goes with a 18 inch or 18.5 inch barrel ( the latest option now being offered ). But 16 inches or 14.5 inches? You do experience a fairly significant drop at those lengths.

Remember too, that the big thing that the 5.56 round has going for it is its velocity. It certainly has little bullet weight. And many people consider the 5.56mm to be marginal as is. So does one really want to reduce the effectiveness of a round that is already somewhat marginal?

Downsides of a longer barrel: More harmonics comes into play.

Pros of a short barrel: Less barrel harmonics. Oh look it is coming to play here. Due to the shorter barrel having to deal with less barrel harmonics, it'll have more potential for accuracy than the longer barrel.

This is a theoretical advantage at best, and not something that people really see in the real world. The fact is that with a 16 inch or shorter barrel you are going to be burning a lot of powder outside the muzzle in a big muzzle flash. And that is going to create much less consistent powder burns and velocities. And that will do as much to degrade your accuracy as any edge in harmonics will give you. At best, one could say that it is a wash, with no real advantage either way.

Though the use of optics makes this negligible, unless you have back up iron sights (which I recommend anyways).

Anyone not using optics today is living like a Neanderthal in the Stone Age. Even our most conservative military branches have wholeheartedly adopted issuing optics to our troops.

Conclusion: Honestly, if you can't decide you can compromise and get an 18 inch barrel, or you know, get two uppers with a 20 inch barrel and whatever length you want for the other one. Ultimately it is up to the person to decide what they want.

I myself did not go with 20 inch barrels for either of my AR's For my AR10, I got a 18.5 inch Criterion. And for my AR15, I ended up choosing an 18 inch from JP Enterprises.
.

 

[jbett98]

After 62 posts, I'm really hoping that he bought something.

 

[Boboclown]

Exactly. That is why new cartridges have been developed like the 6.8 SPC and 300 Blackout.

It is, if you are in the Marine Corps. The Marines have bought very few M4, and still primarily rely on the M16A4 with 20 inch barrels.

All I stated was a simple fact. A fact that you have not contested, BTW. You have simply gone off on discussing other tangential issues

It is negligible if one goes with a 18 inch or 18.5 inch barrel ( the latest option now being offered ). But 16 inches or 14.5 inches? You do experience a fairly significant drop at those lengths.

Remember too, that the big thing that the 5.56 round has going for it is its velocity. It certainly has little bullet weight. And many people consider the 5.56mm to be marginal as is. So does one really want to reduce the effectiveness of a round that is already somewhat marginal?

This is a theoretical advantage at best, and not something that people really see in the real world. The fact is that with a 16 inch or shorter barrel you are going to be burning a lot of powder outside the muzzle in a big muzzle flash. And that is going to create much less consistent powder burns and velocities. And that will do as much to degrade your accuracy as any edge in harmonics will give you. At best, one could say that it is a wash, with no real advantage either way.

Anyone not using optics today is living like a Neanderthal in the Stone Age. Even our most conservative military branches have wholeheartedly adopted issuing optics to our troops.

Few things.

You don't need to go with a 6.8 SPC or 300 blackout just to use a 16 inch barrel, some ARs with a 16 inch barrel work well. If anything, I'd prefer a 5.56 over the 300 blackout in a 16 inch barrel anyways.

As for the Marines, to be honest while I did mention that the military did have other rifles I'm not saying that because I look at the military and say that's what I want in my rifle. Though while the Marines may use the M16 a lot more than the M4, I wouldn't knock the M4 down as an option. Though personally I'd go for the SR-25, mostly because I (doesn't mean I won't recommend it depending on the need) don't like going under 16 inches in any rifle barrel.

Actually, I did go ahead and say that just because it was originally used in the M16 doesn't necessarily mean it has to be used in a 20 inch barrel, or that it really was meant for the 20 inch barrel only though that part I left out. Though M16 having a 20 inch barrel isn't really something I'd go by, but I've been wrong before.

As for the velocity only being negligible in the 18-18.5 inch barrel, not really. Even at 16 inches it's somewhat negligible. The bullet drop isn't that significant, unless you're idea of significant bullet drop is different than mine. Either way a 16 inch barrel is still good enough for medium range plinking.

With a loss of velocity less than 200 (highest I've seen is around 150, around 140 on average, around 110 being the lowest), going from 20 inches to 16 inches, I honestly don't consider it a big issue, not for what I use my AR for anyways. For short to medium distances I'll stick with a 16, it works for me and I'm of the mindset "if it works it's good." To each his own.

As for the velocity, the most drop in velocity I've ever seen going from a 20 inch barrel to a 16 inch barrel was roughly 150, and honestly to me that isn't too much of a big deal for the range I normally shoot at anyways, if I wanted to go past 500 meters I'd just shoot my "marksman" rifle chambered for 7.62x54R.

The reason I said that shorter barrels would have more potential for accuracy is due to shorter barrels being stiff. As for powder burns being inconsistent, well true to an extent. If you're using a M855 (which I personally don't care for anyways) then yes it would be a no advantage either way type of thing. If you handload, however, you can get consistent burn rates in a 16 inch barrel, or even a 14.5 inch barrel. So the whole inconsistent powder burn can be a moot point.

Ah the whole optics vs iron sights thing... I'd still say always keep the iron sights in case they're needed, flip up ones that is. So sight radius does come into play, and to that I will admit that a 20 inch barrel will ALWAYS have an advantage in that aspect.

 

[JRuby]

One thing that needs to be considered in my opinion is once that 556 bullet gets past 200 yards what kind of energy does it have? If all you want to do is ring steel or put a hole in a piecec of paper fine but I am planning to use it as a self defense tool. As far as a shorter barrel to me they are simply easier to navigate in tight quarters.

 

[Boboclown]

One thing that needs to be considered in my opinion is once that 556 bullet gets past 200 yards what kind of energy does it have?

Out of a 14.5 barrel you can still get above 300 ft-lb energy at 500 yards, not sure about anything shorter than that. YMMV

 

[v0lcom13sn0w]

build one!

 

[JRuby]

Out of a 14.5 barrel you can still get above 300 ft-lb energy at 500 yards, not sure about anything shorter than that. YMMV

A whole 300 foot pounds of energy it is believed that a good deer rifle should produce 1000 ad we are talking half again what a 22 long rifle produces. No thanks.

 

[Boboclown]

A whole 300 foot pounds of energy it is believed that a good deer rifle should produce 1000 ad we are talking half again what a 22 long rifle produces. No thanks.

At 500 yards. Within 100 yards you're still in the 1k ft-lb energy area, and you're not hunting farther than that here in NC. You'd actually be lucky to even see out to 100 yards where I usually hunt. For self defense you don't need a lot of ft-lb, so 300 at 500 yards isn't bad for what it is meant for. Not that you'd ever really need to shoot that far for self defense anyways.

Though it isn't energy that kills the deer... Just saying.

 

[JRuby]

At 500 yards. Within 100 yards you're still in the 1k ft-lb energy area, and you're not hunting farther than that here in NC. You'd actually be lucky to even see out to 100 yards where I usually hunt. For self defense you don't need a lot of ft-lb, so 300 at 500 yards isn't bad for what it is meant for. Not that you'd ever really need to shoot that far for self defense anyways.

Though it isn't energy that kills the deer... Just saying.

I agree 100- 200 yards max and yes in rifles energy is a good thing to have - otherwise they would hunt cape buffalo with a 22 or even a 223. Energy delivered down range on target is a good thing.

 

[U8395279]

The best solution to this debate is to simply grow bigger balls, and man up and get an AR10 in 7.62 NATO.

 

[Boboclown]

I agree 100- 200 yards max and yes in rifles energy is a good thing to have

Well, true to an extent. The right bullet and a well-placed shot honestly matter more. Normally deer don't have a high requirement for penetration. At least not the ones here, which might as well be large dogs with antlers. .223 Is also decent for the boar.

The best solution to this debate is to simply grow bigger balls, and man up and get an AR10 in 7.62 NATO.

I already own a PSL, no need for a .308/7.62 NATO for me. Though if I had the money I wouldn't mind a .50 BMG just to shoot...

 

[JRuby]

Well, true to an extent. The right bullet and a well-placed shot honestly matter more. Normally deer don't have a high requirement for penetration. At least not the ones here, which might as well be large dogs with antlers. .223 Is also decent for the boar.


I already own a PSL, no need for a .308/7.62 NATO for me. Though if I had the money I wouldn't mind a .50 BMG just to shoot...

When I need to stop something I dont want to wait for it to bleed out I wantbit stopped to do that you need energy plain and simple and far as shooting deer that is the minimum cartridge that one can use in oregon. Seems most would use a cartridge above the minimum. Yes you can kill a deer with a 22 but that is not even legal.

 

[Boboclown]

Again, not really. Simple research would say that 1,000 ft-lb energy really isn't necessary. It's just insurance, and a lot easier to just go by that as a guideline. You need a well placed shot that takes care of the vitals. Not everything used for hunting deer reaches 1,000 ft-lb energy. Same for hogs too, and those are some tough pests.

 

[JRuby]

According to a document by Chuck Hawks "the killing power of big game bullets" he states that " the practical killing rsngevof any cartridge is ultimately limited by how much energy remains" . I will stick with my position on energyvwhen it comes to stop something now.

 

[Boboclown]

You can stick with it all you want. Because it's just easier for people to follow that than going into detail. But not absolutely necessary.

 

[JRuby]

Believe what you want.

 

[Boboclown]

I will "believe" what I want. Considering that there's some people here, as in where I live, who hunt with revolvers. And they don't exactly meet that 1k energy standard with the loads they use, even at 25 yards.

 

[JRuby]

Thats find thats why they use 22 for shooting elk. Most pistol shooters choose magnum cartridges for shooting big game fairly close. Many consider a 41 or a 44 magnum as the minimum cartridges for hunting big game.

 

[Boboclown]

And depending on the load those rounds will not meet the 1000 energy mark.