Im tryin to decide on what upper to get i want something light to carry into sections coyote hunting, so a bull barrel is out of the question, What is the max range for a 16" regular barrel on a m4 upper?

max range?  what do you mean?...  16" barrel will give you enough velocity to be just as accurate than any longer barrel... sometimes more accurate because it'll have less barrel whip being shorter...

your max range is going to depend on the ammo you choose... not your barrel... if you use softpoint rounds or varmit(rapid frag) rounds... if you can see it you can hit it and kill it...   a 16" AR coyote gun is a good light handy accurate weapon capable of blowing those dogs to the dirt...  

You question is your answer.  How far can YOU shoot accurately with a 16 inch barrel?  Exactly, how accuratey the barrel will shoot over range is mostly dependent on how accuately YOU can shoot.

thanks for the help guys i appreciate it!

+1 Troy.Its not that the .223 cant be accurate out to 4 or 500 yds it is but like troy said its the lethality issue out to those ranges..223 is best kept at under 100 yds for a carbine and 200 for a 20" rifle.If you want to make sure somethings not getting up past 1 or 2oo yds go .308,If Im in an area where shots are going to be taken at 4,5 or 600 yds although very rare Ill use my M14 type rifle.

so does barrel length affect accuracy or not?

cause i thought that it did (someone yesterday said it did not) cause bbl length affects velocity which i always considered had an impact on accuracy--i.e. faster bullets are less affected by wind and gravatational forces

*this is not a hyjack

Quoted: Im tryin to decide on what upper to get i want something light to carry into sections coyote hunting, so a bull barrel is out of the question, What is the max range for a 16" regular barrel on a m4 upper?

How many hunters can reliably make a 450 yard shot on a coyote with a carbine?

That would be an interesting statistic.

Quoted: How many hunters can reliably make a 450 yard shot on a coyote with a carbine? That would be an interesting statistic.

How many hunters can reliably make a 450 yard shot on a coyote with any rifle...

Quoted: Quoted: Im tryin to decide on what upper to get i want something light to carry into sections coyote hunting, so a bull barrel is out of the question, What is the max range for a 16" regular barrel on a m4 upper? How many hunters can reliably make a 450 yard shot on a coyote with a carbine? That would be an interesting statistic.

I'd imagine a lot of experienced hunters could do that, just maybe not every single time.  Wouldn't want to with a 223 because it quite likely wouldn't kill it.

For a reference data point - I'm a relatively _inexperienced_ hunter, and this past weekend at a deer lease in Mexico, I shot a hog.  The hog was roughly the same dimensions as a large coyote in terms of target size where it counts - but obviously they move around a little slower.  I was using a .223 coincidentally, but it was a bolt action long-barrel regular old rifle.  I took my shot at roughly 100 yards, and I called it, and the hole went exactly where I called it (just above and behind his left ear, right through his neck and out the bottom).  Pig fell over in the split second it took to re-acquire my sight picture with the scope, kicked one rear leg off and on for a minute or two, and was dead dead by the time we walked over to it.

Extrapolating senselessy from this singular data point (the only time I've ever hunted with a .223), I would imagine I'd have no trouble making a relatively imprecise rough neck/head-area shot in general at 300 yards with the same gun on the same animal, and from there I'd speculate that on an actual coyote, and with a 16" carbine instead of the bolt-action hunting rifle I was using, perhaps that range would drop back to 200.

And therefore, an experienced hunter could probably do twice as well as me and do it at 400, but then again why would you go past 200 on this shot with this gun anyways, it's just gonna bleed out in the brush somewhere for hours

ive shot i bet over 10 yotes 300 yards to 350 with my .223 weatherby bolt action, everyone one of them was dead at the impact of the bullet.  All the shots were vital shots, ive never had a prob killin yotes at 300 yards with my .223.  The load were ballistic tip BH 55 grainers. my .223 is my favorite yote rifle it has plenty of range and very little fur damage.

Thank you Troy, a very clear and thorough explanation.

I just wanted to add to Troy's excellent anology and address barrel profile, length and accuracy.

In the theoretical vacuum Troy mentioned,  not barrel profile, nor length would have any factor in accuracy.  In this vacuum, where all things remain constant, every rifle will put the same bullet in exactly in the same place as the last one.   However, in the real world, there are many evironmental influences to consinder, as Troy eluded to.  

Let's first consider length.  Length does two things that we should consider - stablization, and velocity.

Stablization occurrs by 'spinning' the projectile a certain number of revolutions prior to exiting the barrel to reduce 'wobble' in flight.  'Spin' is needed to keep the projectile moving in a straight line in relationship to its axis.  The amount of spin needed depends on the velocity and weight of the projectile.  Generally accepted is, the heavier the weight the more spin needed.  

Velocity is the speed of the projectile.  The faster it moves, the more stable on its axis, (if the correct spin is applied) and the less time it has to be affected by outside influence,  i.e. gravity and wind.  The velocity of the projectile is determined by the force created by the controlled explosion of the round + the time that force is allowed to push that round minus the friction created from them barrel.  In other words, it takes a certain amount of time for the powder to completely burn, creating the peak force on the bullet itself.  If the round leaves too early, and not all of the powder burns, you have less force.  If it leaves too late, the friction of the barrel slows the bullet.  In regards to the .223, the 16" barrel does not allot enough time to burn all of the propellant and create the peak velocity, thus reducing RPM's, thus reducing stablization in flight, thus increasing a greater impact from the environments.  This principle is exacerbated with distance to impact.

Let's return to the barrel itself.  Accuracy can only be determined by comparing more than one round fired.  It begins with the explosion inside the cartridge which is determined by many things beyond the scope of this print - powder consistency, powder amount, case length, concentricty, neck tension, bullet weight consitency, aerodynamics consistency, etc, etc, etc.  Bottom line, consistent chamber pressure applied to exactly the same projectile.

So, now, we have absolute consistent chamber pressure and concintricity of the bullet.  Accuracy know is taken over by the device in which the projectile is propelled, the weapon.  We have already determined that ballistics indicate the 16" barrel does not offer the projectile the amount of time needed to completely burn the powder, thus reducing velocity, thus reducing stablization, thus increasing environmental affects of the round.

The 16" barrel therefore, is less accurate than the 20" barreled weapon.  The exact margin I cannot offer.

Barrel whip?  Barrel whip is the result of the barrel vibrating under the stress of the chamber pressure caused by the explosion of the cartridge and the projectile traveling down the length of a tight barrel.  Barrel whip will occur exactly the same if the chamber pressure and force exerted on it, is exactly the same, each and every time, without regard to the environment.  See above.

The first two environmental effects of the round, while traveling the length of the barrel is harmonics (whip), and heat.  As stated, the whip will remain the same, given consistent circumstances ,  However, enter heat.  The heat created by the exposion will change the whip of the barrel.  When metal heats, it's easier to bend.  The heat generated from the first shot will affect the strike of the round of the exact same bullet we described earlier, simply because the barrel will flex differently with the subsequent round.

Whip is determined by the force applied.  Whip is the bending of the barrel.  Bending of the barrel increases with heat.  Heat is created by the firing of the round.  Heat increases with each round fired.  Heat is dispersed by the amount of metal it is applied to, be it thickness or length.  The more metal available, the less heat affects the bending of the barrel.  The more time it takes to heat the barrel, the less deflection of the round.

Does length matter?  Yes.  So does circumference.  At least as it is applied to accuracy.

I implore Troy, and other experts to clarify, expand on, or correct any points.

Semper Fi!

I don't think barrel length is going to be much of an issue when it comes to stabilization.  From what I understand, 7" barrels don't have a problem achieving a stable .223 bullet in the weight range the twist rate covers.  I think a majority of the propellant is consumed, gas pressure providing velocity,  before 11.5", building the rest of the way as the barrel length is increased.  Unless you are firing bullets out at the edge of what your twist rate supports, I think they are plenty stablized enough for decent accuracy.  I know of <MOA out of a 10.5" barrel, don't think there was any problem with stabilization out of such a short barrel.  Of course, spin rate over distance is going to be equal to your twist rate after the lands take hold of the bullet, and then keep it there.

RULE NR 1:
Never even try to shoot an animal if you have the slightest doubt the shot wouldn't kill it.
Shooting any animals isn't a sport.

Quoted: 16" barrel will ... be just as accurate than any longer barrel... sometimes more accurate

Um...Ok...

Can someone elaborate on the point about the powder not fully being burned on a 16" barrel--I thought that this depends on the type of powder/accelerant used and that for modern-day quality cartridges this is no longer an issue--ie. almost all the powder has burned when the bullet leaves a 16" barrel. Is this not the case?

BJ

Quoted: .  16" barrel will give you enough velocity to be just as accurate than any longer barrel... sometimes more accurate because it'll have less barrel whip being shorter...

No, not the barrel whip thing again  

Longest shot I have ever taken with any rifle was with my Oly with the 16" barrel.  It was about 550-600 yds.  I don't know for sure because a truck odometer can't be that accurate. The odometer said it was over 3/10 of a mile, getting close to 4/10, but hell my bullet dropped a hell of alot.  It wasn't that amazing of a shot either with the 6-24x scope turned all the way up and my target being about a 3 foot square.  It was pretty cool, and when asked if I could do it again I said I am not even going to try.  They thought I was just that good and I wasn't going to tell them I just got lucky.