I am building a new upper, and I am deciding between a 16" and a pinned 14.5"

Most of my ammo is what I can get in stores, and its .223 REM, I can rarely find M193 variant of 5.56 NATO on shelves and what I do have I am storing. And, I can't recall seeing and M855 variants in the last year or so on shelves.  So - My ammo is either .223 REM and civilian versions of M193 (mostly Fed XM193).   I haven't been able to stock up on any home defense rounds in an significant amount beyond a box of .223 PDX1.  Just none available or at monstrous prices.

According the the arf15.com Ammo Oracle, on page 21 of the printable .pdf, It gives the following data for a specific environmental condition comparing 20 through 11.5 " barrels.

Distance to 2700 fps for reliable fragmentation (M193)

20" Barrel     190-200m
16" Barrel      140-150m
14.5" Barrel    95-100m
11.5" Barrel    40-45m

This chart is saying there is a 47-50% increase in reliable fragmentation range of a 16" barrel over a 14.5" barrel.  This seems significant to me.  I know that lethality is not limited to fragmentation range, but there still seems to be a great change in distance to be deadly.  My personal goal is to be at lethal as possible to 100 yards for HD defense and SHTF.  But given I could be using .223 REM, velocities could even be lower.

Is this a significant tradeoff?  1.5 inches for 50 meters?  The oracle is a large document, I can't digest it all, so - any comments on this?  It just seems to be a drastic change in distance that most people ignore when they discuss why they choose a 14.5 in barrel.  So, why is that?  Is it that skip the .223 REM no matter what and 95-100m is fine enough? And have 1.5 inches less for CQB?

The document does not say what the twist rate is, if that makes a difference.  I am looking at 1:7 twist barrels so if someday when the ammo shortage goes away and I can find 69+ grain defense ammo, I can use that.

I went with the 14.5" mid-length pencil barrel.  Great light weight option. YMMV.

Generic .223 ammunition might not fragment at 0 yards, let alone 100.  I would recommend utilizing some of the other defense loads.  Personally I use 75gr TAP in a 10" barrel.  For home defense shorter is better.  On the other hand not being able to swap your flash hider/muzzle break/sound suppressor is kind of annoying.  I have a 14.5" pinned gun and I've been thinking about SBRing it.  Then again - if I payed for the stamp I'd probably cut the barrel back another inch so it would be flush with the hand guard.
 

Yes, 100fps + difference more than makes up for having a gun that is 1" shorter (not 1.5" shorter, because the FH has to extend to at least 16" anyway unless you have a short barreled rifle).  You won't even notice the inch in length, but that velocity difference is HUGE and could make all of the difference.

Sure, you can say "well, just use special ammo".  Well, that's all well and good.  The only problem with that is you might not be able to get, or have access to, such special ammo.  As we are seeing during this panic period, ammo is in short supply like never before.  The problem will only get worse during SHTF, and you may only have access to whatever you can scrounge, so any bit of velocity you can get to increase lethality is key.

Increased velocity also helps the gun shoot flatter for longer distances.  And with a 16" you can get a mid length system which includes longer sight radius (more accuracy) longer handguard for more grip real estate, a smoother operating gas cycle, etc.  

Bottom line, it is just not worth giving all of that up for 1" less in length.  

In general, distance buys time.  

At 95m, you have more time to engage the threat, assess whether it's neutralized, and re-engage.  Lethality is not always critical if neutralization or suppression will do.  

Up close is where both speed and lethality are critical and where every advantage counts.  14.5" is inherently a compromise length, though in my personal opinion, it is the best compromise and therefore overall the best barrel length for general purpose use in a 5.56MM platform.  

If the difference between 14.5" and 16" make no difference to you in maneuverability in tight, confined spaces, more power to you.  Generally speaking, the shorter the OAL, the faster you can manipulate the weapon in close quarters.  

Mentioning that a 14.5" barrel is in fact at or close to 16" OAL with the muzzle device included is misleading, as it obfuscates the fact that the muzzle device adds the same amount of length to a 16" barrel.  For those limited to Title 1 restrictions, the key factor is not the barrel length per se, but "as short as I can get."  Those with SBRs rarely choose 14.5" or 16" barrels for CQC specific roles.  

I choose 14.5" as a general purpose length not because it's ideal for CQC, but because it's the longest I would want to have to do it with.  Incidentally, the OAL is almost identical to a suppressed 10.5" carbine.  

Once again, distance buys time - if forced to choose, I would try to stack the close-range advantages over longer range advantages.  You never can guarantee what will happen in a gunfight, but you're more likely to get the opportunity to re-engage at 95m than to be able to afford the extra .5 seconds at 9m.  

~Augee

Thanks for replies.  I hope more chip in.  My my personal build, I will be putting a flash hider on either length.   I understand the NFA laws, and want to bout off a SBR to a later date.

.  For home defense, shorter is better.  It is unlikely you will be making shots beyond fragmentation range.

.  For SHTF, who knows?  The ammo is still lethal a long way out.  Optimize for the more likely scenario.

.  Keep looking for better ammo.  

It is not misleading, the difference between a 16" and a 14.5" is LESS THAN the 1.5" of barrel length because the muzzle device on the 14.5" has to be extended longer than the normal A2 to make the barrel 16" total.  

Are you saying that the muzzle devices that go on a 14.5" non SBR are not longer than a standard A2?  

If yes, then you admit that the length difference is LESS than 1.5".

You're making the assumption that A2s and A2 length muzzle devices are all that anyone uses. There's a fair number of muzzle devices in popular use that are already long enough to bring the barrel to the correct OAL, including but not limited to the Smith Vortex, the PWS comp, or any AAC or Surefire suppressor mount.

You also make your argument based on permanently pinned muzzle device, though you mention SBRs, you assume that no one would do that, so everyone must have their muzzle device pinned to 16".  

Also, related to your overall argument, not whether or not it is misleading to make a statement implying that all muzzle devices on 14.5" barrels must be extended varieties, and no one would ever put an extended one on a 16" barrel, your opinion that even 1" does not matter or is not worth it is your opinion.  I do not share your opinion that 1" is anything to scoff at, and there are heated discussions about 11.5" barrels versus 10.5" barrels as well, and a good proportion of people (not to mention the majority of the military issued short barreled M4A1 variants) choose barrels in the 10" range over those in the 11.5" range, though 11.5" barrels have been around longer and are arguably more reliable over the long term.  

The length of the CQBR's 10.3" barrel is predicated on the very simple concept of "as short as possible and still be able to mount [a KAC] suppressor."  

That an inch of OAL is not worth it is an opinion that you're entitled to and welcome to state, however, not all agree.  

~Augee

Ok, so what percentage of average Joe Q public that owns 14.5" barreled ARs do you think are comprised of short barreled rifle owners?  

Less than 1%?  

More importantly, since the thread was specifically in reference to the OP, and he has NO intention of going that route, you can wipe off that 1% in his case as it isn't even an issue.

Not everyone will use an A2 on their 16", but the vast majority will as that's how the vast majority of ARs are set up.  The longer FH on the market don't offer some crazy advantage that warrants the hassle and expense of having most people swap them out, esp for the cost.  For the flash reduction, compensation, and short size of the A2, it's really a great bargain.

Also, when you're talking about how important length is, I doubt anyone that concerned with length where "every inch matters" is going to put voluntarily putting on a flash hider that is an extra inch longer unless they're a fool.  

One thing is sure though, if you have a 14.5" AR, you will NOT be using a standard A2 because you legally can't.  You have no choice but to extend the barrel to 16".  

And like I said before, 100+ fps for 1.5" of barrel, and only 1" of overall length is HUGE.  Esp if you want this rifle to be your main combat / SHTF arm.  If you're wanting to just get a weapon for "sweeping rooms", close quarters, and indoors defense, get a different weapon.  You will hardly be able to notice the effects of that inch if you try "sweeping rooms" with your AR anyway.

So yeah, loosing 100+ FPS for an inch in length is NOT good for a general purpose gun, unless your "general purpose" is going to comprise of 50 yards or less.

You could use a 16" barrel with a thread protector instead of a muzzle device. You will experience more flash of course, but you get the velocity of a 16" with the length of a pinned 14.5.

+1

Yes, the OP is talking about pinning his barrel.  

Does this mean that we can not have a generalized discussion about 14.5" barrels versus 16" barrels and velocity?  Chances are, the OP is not the only one curious about it, and since the topic was brought up, a discussion can develop.  Or do we adopt a Yahoo Answers model where only the OP's specific question can be discussed and once answered the topic is closed?  

Either way, the OP is talking about using said barrel for "HD."  



Once again, sure, you're correct that the majority of 16" ARs have A2 comps on them.

At the same time, the majority of suppressor mounts will bring a 14.5" barrel to 16".  If a user has a suppressor or is considering a suppressor, whether using a 16" or 14.5", they will need to use the same mount.  Many who pin muzzle devices on 14.5" barrels pin suppressor capable mounts, either because they already have one - or in anticipation of one they intend to purchase.

Does this apply to the OP?  Who knows, he never mentioned anything about suppressors - once again, this is in a general sense regarding 14.5" barrels versus 16" barrels.    



Is it?  Why?  At what range does relaible fragmentation become critical versus becoming a non-issue?  What happens between 100m and 150m that makes it so critical that you get reliable fragmentation, but is suddenly a non-issue at 151m?  Or do you use relaible fragmentation only as a measure of the effective combat range of the weapon?    



In that case, why stop at 16"?  18"'s and you get even more "lethality" out of the cartridge for even further.  Why not a bare muzzle 18" with a thread protector?  It's only .7" longer than a 16" with an A2, and you get even more velocity and range.  Right?  It's less than an inch of maneuverability, as you say.  

Where is the line and why?    

Have you ever stopped to consider why so few of those organizations and individuals for whom NFA does not exist or is not relevant do not usually select 16" barrels, and those that do are almost always for specialized, not general purpose uses?  Or do you simply assume that you're smarter than all of them and that their institutional knowledge and experience is meaningless?  Nor am I merely talking about legacy systems, or those that are unaware of the option of 16" barrels - the HK416, SCAR MK 16 MOD 0, and the majority of the IC submissions were all developed with barrels ~14" in length.  The fact that they do use 16" barrels for specialized purposes, whether in "recce" form, support weapon form (M27), or .308 versions (MK 17 MOD 0) attests to the fact that they are in fact aware of 16" barrels and their capabilities.    

Nor is it that I don't understand your argument and where you're coming from - I disagreed, and stated my reasons why.  To which, rather than to try to address the reasons for my personal preference and why you disagreed with them, you seem to have become offended that I even dared to disagree with you first by honing in on what was essentially a throwaway comment (my use of "misleading," versus "non-issue to me"), though I addressed it nonetheless, and then dissembling by hiding behind the OP when you were the first to make a generalized statement about barrel lengths ("Bottom line, it is just not worth giving all of that up for 1" less in length.").  

You say the increase in FPS (along with other factors that could be argued) is "HUGE" but never say why.  Certainly, it's statistically signficant.  But is it practically?  I do not think so.  Why?  Because at 95m you can re-engage.  Speed up close matters much more, in my opinion.  In a general purpose weapon you expect to use for both CQC and conventionally ranged engagements, I think it's well worth the cost.  You do not.  Which is fine, you're not the only one to feel that way, but you've decided to detour into side arguments about muzzle devices and NFA, rather than simply addressing the point of why other than "it goes to 11!" you feel that those FPS are so important in a practical sense.  

Flatter trajectory?  I have no problems hitting to 600m non-FF with 14.5".  Yes, the trajectory is slightly flatter.  Does it matter?  Not to me.  Next question.  

Mid-length gas system?  Not everyone is enamored with mid-lengths.  In my opinion, carbine is better for 14.5" barrels, which is what I use, for reasons already stated.  You also somehow link gas system to sight radius.  The two are not inextricably linked as FF handguards and rail mounted sights can be used with either length, and for use with optics, is irrelevant anyways.  The same again applies to "grip real-estate."  

"Smoother operating gas cycle" is subjective in importance.  And even if you run with your arguments - why not then go with an intermediate length or even a rifle length gas system with a 16" barrel?  Would they not maximize all those factors?  

TL;DR:

Regardless - if you're interested in discussing why exactly you feel that the 100m-150m (95-140) envelope is so important to have relaible fragmentation compared to the importance of having it at <100 or >150, I will be happy to discuss that civilly with you.  

If you're argument consists of "one inch doesn't matter!" I think it does - we agree to disagree, and I'm out of this thread.  Likewise if we're going to continue playing ring-around-the-rosie about tangential issues, or your argument consists of nothing more than "the difference is HUGE" without explanation.  

~Augee

For my plans, either barrel I select, will have a SEI Vortex flash hider on it.  From what I read already, its the best, or in the top 3.   And in the future, I have the ability to attach a SEI suppressor.  I probably should have been specific in my post, but also like to see general discussions.  So for me, the 1.5 inches for 40-50 meters is a decision I need to make.  Because - I don't know if 1.5 inches will make any difference to me inside a building for HD.  But maybe people with more experience, do know.  I won't be wearing the kind of gear our troops use when breaking down doors.  I am aware of the disadvantages of a pinned muzzle device, and that is a different input into the decision.

So far, I haven't been able to find a good table, summary of defensive rounds and where their reliable lethality/wounding distances are for different barrels/velocities.  I think it would be a good project for someone with that information to present it.  I have seen one table (a jpg of a table actually), without references, that a Hornaday TAP 77gr is effective to 110 yards out of a 14.5" barrel, but have not seen anything to corroborate it.

I work in an urban environment, in and around vehicles, and with team mates. Shorter barrels/weapons are easier to move with and faster in dynamic situations.  If you're relying on fragmentation then your probably going to be disappointed. Bullets do strange things, especially after hitting glass, plastic, wood, etc.

Good luck justifying a shoot over 50 m, let alone 150.

Ymmv,
Rob

To be fair, it IS a bit off topic. It's just as valid for him to say "you've majorly derailed the thread, and now it's a SBR vs non SBR discussion, which is off topic".



So then velocity isn't important? More velocity isn't inherently better then less with light weight rifle bullets? Not being snarky - but given the legal restrictions in play 14.5 is a rather poor comprimise in the grand scheme of things IMO. I would agree with SBR - but that;s not THIS discussion. I personally agree (and have shot both a bunch) that the 1" in length between both non-sbr rifles is barely discernable and not worth the velocity tradeoff.

So then why not a 16" with a bare muzzle (SAME length as a 14.5) and better muzzle velocity? Doesn't that rather obliviate the 14.5 barrel for non suppressed, non-sbr rifles by your logic? That's a poor arguement, cmon man.


Aagin, you need to seperate the NFA from the non-nfa guns. They're (for the high % of civilian rifles sold)  different animals. With a non-nfa gun - you're not able to get the "most" out of a 14.5 gun, but you CAN out of a 16" gun.


IMO, you came across as dismissive and a bit snarky yourself. You prefer the 14.5 because the big army uses it, and you prefer it for SBR's. He made valid points which I understood fine, they just disagreed with yours.



Some I agree with, some I don't here - but these are your opinions and preferences. Just don't expect others to fall over themselves sharing their reasoning, when you post things like: "Yes, the trajectory is slightly flatter. Does it matter? Not to me.", which is the EXACT same reasoning as " One inch doesn't matter to me".

The detour isn't his alone bud :).

That said - I myself prefer the 16" barrel. I don't find the loss of velocity worth the miniscule difference in OAL, since I run an A2 flash hider as a suppressor mount (SWR renegade). I aslo live in a non SBR state, and get paid to carry a rifle.

Fair enough - I was approaching this as a generalized discussion of the merits of 14.5" barrels versus 16" barrels.  Separate from all other factors, what is "ideal" were there no legal restrictions?  I believe in isolating variables - determine the ideal barrel length first - then determine whether or not it's worth pinning based on legal criteria.  I would work from the optimal back to the feasible.  The poster whom I responded to made no mention of anything relating to pinning than length.  



You're still not answering the question - and your point of view seems to make less sense to me than his - why does NFA make the difference in this case?  Why do you agree with SBR but not pinned?   If it's because you like to be able to change things out on your weapon, install different rails and gas blocks, then this bears mentioning as part of the logic for selecting a 16" barrel.  This is not related to fragmentation velocity, it related to person preference.  

The question "more velocity isn't inherently better?" is ducking the question once again, leading to your next point:  



I am not advocating any of those options - I am extrapolating the logic of "more velocity is better."  Where is the line drawn between length and velocity?  Which is the crux of my question, which I've framed both in terms of rifle OAL and fragmentation distance and no one has answered.  Why 16" over 18"?  Why 18" over 20"?  The logic is not mine, it is that of the poster I responded to, in which case, yes it does obviate the 14.5" barrel, as it could well be applied to the 16" barrel versus the 18" barrel.    

What I am asking, and what I have been asking from the get go is "where is the compromise line between velocity and OAL, and why?"  It has not yet been answered.  



Again, isolating variables.  Discuss the issue and question at hand - the relationship between bore length and velocity and fragmentation range.  What is the ideal that we would purpose "without rules," so to speak.  Then re-introduce other variables.  Since the OP's question was framed in terms of velocity and fragmentation range, I believed that it was appropriate to isolate that single aspect.  If others feel that that is inappropriate, then I will concede "off-topic" and abstain in the future.  



Did I come across "snarky" in my original response after Blain's response?  If you think so, that wasn't my intent.  If you're talking about my most recent response, yes, by this far in to it, I've gotten a bit "snarky" myself.  I understood his points just fine because I've heard most of them before.  What I have not heard is why fragmentation is so important between 100m and 150m relative to how important it is inside of 100m, but not as important any more at 151m.  

Once again, it's leading us further astray - but at what point did I say that I preferred 14.5" barrels because "the big army uses it?"  I pointed out that most military forces choose ~14" barrels and that their institutional experience may be of use to the discussion - but only after expressing my own reasons for preferring 14.5" barrels.  



I expect no one to "fall over themselves" to agree, but you're right, I expressed that poorly, I am trying to get a "straight" answer to what would seem to be a simple question, that deals solely with barrel length, velocity, and fragmentation distance.  I also disagree that discussing the importance of range/velocity/barrel length is not a detour given the way the OP's question was framed, and a non-NFA related discussion of what velocity is a critical threshold is entirely relevant.  Other external factors [such as NFA] can be far more effectively assessed once you have a baseline.  

What is critical about 100-150m that makes it so important to have velocity within that envelope.  As a follow up question to that - what happens after 150m that makes it not important any more - or, to frame the same question in terms of barrel length - what about the difference in length between 16" and 18" makes it significant when it is not at 14.5" to 16"?

Either your argument is "velocity is king," in which case I see little reason to go with a 16" barrel over an 18" or 20" barrel - no, I would not want to do CQC with anything longer than 14.5" - but I've done it with 20" barrels, as have many others.  So - it can be done.  If velocity is king - why not recommend 20"?  Thousands of rooms have been cleared with M16s - and the hovels in some other countries are a whole lot less roomy than most of the homes in the U.S.  

Or, you agree there is a compromise length/velocity, which then levies a penalty against the other.  You can argue 1" doesn't matter - but that opens you up to extrapolations that lead to the above - if 1" doesn't matter between 14.5" and 16", why does 2" matter between 16" and 18"?

I would argue:

A suppressed 10.5" weapon (often agreed by most to be one of the most ideal CQC weapons) has roughly the same OAL as an unsuppressed 14.5" barreled weapon.  Meaning that the tactile execution of CQB is essentially identical and you retain this continuity - you only need to train for one OAL.

100m is considered by many to be the outside limit of "point shooting" and/or "point blank" range.  Not just for you, but for the enemy as well.  

"Supposedly" 90% of infantry engagements occur within 100m or less.  In Afghanistan the ranges extend, but in Afghanistan you also have machine guns, grenade launchers, mortars, and most importantly, fellow teammates.  Suppression by volume of fires in a target area is a valid TTP there.  

I say this not because "we should do what the military does," but it's a useful piece of information - if organized military forces are engaging outside of 100m relatively rarely, how often are civilian homeowners/defenders and law enforcement?

Distance = time.  Didn't die?  Shoot him again.  At 150m, most likely you're doing one of two things - suppressing to keep him from bothering you while you withdraw so you can get to where people aren't shooting at you, or you're intending to close with and destroy.  The same goes on the defense, too.  Either the enemy has to continue closing, now while wounded, or even if you didn't kill them, you took enough fight out of them to get them to leave you alone.  On the other hand, the final assault, if there is to be one, is almost always initiated inside of 100m if dismounted.  100m is at least three three to five second rushes, "Im up, he sees me, I'm down" - the world record for the 100m dash - full speed, is just under ten seconds.        

Therefore, assuming one agrees that velocity is not king, but that a compromise must be reached somewhere - 100m is in my opinion, the best threshold, it covers 90% of engagements, and it allows for reliable fragmentation within your critical range.  In my opinion, 100m covers "general purpose" adequately, beyond which it's not a question of 1", 1.5", or 2" - in my opinion, it's "as short as you can get."  It's an adequate length for CQC.  It fragments reliably within 90% of engagements.  You can still hit out to 600m with it.  None of these facts is contingent upon an NFA weapon, nor do they diminish when NFA is included in the equation.  

So, why - in your opinion, besides "more velocity is better" is fragmentation at the 100-150m range is so important?  You obviously agree that length is important at some point for CQC, otherwise there would be no reason to argue for a 16" barrel when more velocity can be had with an 18" or 20" barrel, and it has been historically proven that CQC with a 20" barrel is possible.    

~Augee

"oh,  you just shot me with 14.5" barrel M4 instead of a 16" barreled RECCE, time to walk away instead of die...said no Haji ever"...if you have yo shoot some one once it wont hurt  a few more times...that is why there is a 30 round mag. And as noted  beyond 50yds.. Is hard to justify but if you have begond that, unload on em, just better hope they are in the act of a serious felony to avoid loony DAs.  

As an example, the Tyler , TX courthouse shooting, if Wilson had a rifle, from the apartment, elevated position and engaged the suspect, he may have had better effect or even ground level with rifle...but regardless

Eta: shoot to stop threat, not kill or to do one shot wonder.  And real life rarely goes to theorized out comes...

Ok, I will attempt to address all of your questions, Augee.  If something is not answered to your satisfaction, let me know and I'll further elaborate the best I can.

Firstly, to address the “off comment” point that Toxie brought up.  It is true that I was trying to directly relate to the specific question that the OP asked.  If I was to go off topic and tell him my ideal solution, it would be for him to forget the AR at all for home defense and get a pump action 12 gauge shotgun.  Keep the AR for SHTF / revolution duties, and allow the shotgun to take over the role of primary home defense arm.  Though, that wasn't his question, and I wanted to answer what he asked as I hate having someone derail a thread of mine when I post a specific question.



Again, I find this to be a bit off topic as he was specifically inquiring between two specific barrel lengths.  A pinned 14.5” and a 16”.  If you ask me personally what the ideal barrel length is for a 5.56, it is 18”.  Again, that is my personal opinion, and I could extrapolate further as to why I think that, but we are getting off topic again.    




I think you are missing the point entirely.  Again, you're assuming specific ranges and numbers with specific ammo types, M193.  What I first touched upon in my original response is that you may not have the chance to custom choose your ammo, esp in a SHTF situation.  The OP already stated that regular 55 grain .223 was all he could find.  What do you think would be available in SHTF?  Whatever he could get.

You're too hung up on specific ranges.  The fact is that the 16” will have a significant velocity edge at ALL distances than a 14.5” barrel, so any ammo type he uses, he'd get more potential lethality out of a 16” than a 14.5” at greater distances.  What I'm saying is that, whatever the max threshold for fragmentation is with an ammo type for 14.5” barrels, it will be MORE with a 16” barrel.  With M193 and M885, the velocity gains are around 100 fps, which increases fragmentation range around 50 yards per round. Likewise, generic 55 grain .223 will have higher velocities in a 16” than a 14.5” and a greater range of potential fragmentation.

It's not so much that the exact distance is so important, it's that you have a greater margin of error, a greater %, more odds in your favor, etc with the 16”.  I'd rather have it and not need it than need it and not have it.  It would be a real shame, for instance, if you shot someone at say 50 yards, which happened to be the fragmentation threshold for whatever round you had in your 14.5” AR, and the combatant didn't drop right away, fired back, etc when if you had a 16” that same round would have fragmented.

I'm not saying that a non fragmenting .223 is nothing to scoff at either, or that it wouldn't be effective, but it is well documented that if a round fragments it is potentially much more effective.  Again, keeping the odds in your favor.  Velocity is what separates pistols from rifles after all.

Also, this is specifically addressed to the OPs original question, with some explanation as to why.  I'm not discussing “drawing the line” as to what the ideal barrel length is, not going there at all.  It's not like we're talking about a length difference of 4”+, either.  But for a difference in OAL length of 1” - 1.5” max, depending on muzzle device selection, 50% increased fragmentation range is a substantial difference.  

If you're JUST cleaning rooms, then  maybe that inch matters more.  I personally have found weight to be a bigger factor in handiness than length.  I've handled lightweight 16”s that were much handier than some 14.5” guns.  An inch is harder to notice, half of a pound?  A lot more noticeable.

This + permenantly welded SEI Vortex flash hider = best general purpose setup for my needs/req's.

Whew-eee, yes... we certainly could swing way off topic on that one, but I agree - topic for another thread.    

I think you and I are approaching this from a completely different perspective - you are approaching it in a relative sense, which I can concede, may be more in line with the OP's original question.  However, I prefer to look at it independant of comparison.  14.5" is not 1" or 1.5" shorter than 16" - nor is 20" 4" longer than 16" - each stands on its own and lies on a continuum where you sacrifice different things for different reasons and strike the most favorable compromise.  

Regarding the velocity and range data - it's not that I'm hung up on the Ammo Oracle's specific data, I have been using that data to "anchor" the conversation.  M193 and M855 are pretty decent "baseline" loads, which is likely a large part of the reason they were selected, and the Ammo Oracle's numbers give us the same basic metric to discuss what we sacrifice and where.  At the end of the day, few decent loads perform significantly worse than the two, and 55gr. FMJ is probably the most common load available in either 5.56MM or .223 REM.    

I don't disagree that velocity is good.  My question is how important is it, and how does that translate practically?  

According to the baseline data that we're working off of, your assessment of a 50% increase is correct.  My question is what that 50% increase translates to.  You offered an example of hitting a threat within that 50% window, where one would fragment and the other would not.  Neverminding that I think we can both agree - gun play is not something you should do if you're not prepared for "freak occurances," I've seen 5.56 do some crazy unexpected things.  

Taken at face value, this seems significant, 50% increase in fragmentation range - however, in my opinion, when you consider all of the variables (or as many as you can realistically process), that 50% increase doesn't amount to much.  If 90% of engagements occur inside of the effective threshold of both, that leaves only 10% remaining in which that 50% is even relevant.  Then - once again - using the baseline data - small variations don't change the argument much.  

Once again, to "play the game" so to speak, and use the Ammo Oracle data as a baseline, and to run it as a straight comparison of 14.5" versus 16":

Available data suggests 90% of engagements occur inside 100m.  Both are "effective."  

Of the remaining 10% - this includes not just engagements in the 100-150m threshold, but the whole gamut of engagements at 200m, 250m, 300m, 600m, ect.  

Being conservative - let's say that of the remaining 10% of engagements outside of the effective fragmentation range of the 14.5" barrel - fully half of them occur within the 16"'s fragmentation range.  That's still only a 5% theoretical increase in effectiveness.  

On the other hand it's a 10% increase in barrel length - and I specify barrel length, not weapon OAL specifically.  The assumption of course being that both barrels are to be used on an otherwise similarly configured weapon - you will shoot with the stock in the same relative position, your support hand and firing hand in the same relative position, ergo - the relevant increase in length is the increase forward of your support hand, not behind it.  

Therefore, to me - the question is once again, while a 50% increase in range is a statistically significant number - considering the variables in play - the practical significance of that 50% increase is down below 5% and at a 10% penalty in length.  

And all of this is dealing only with single shot effectiveness - it does not even factor in to the equation some of the other things that I mentioned such as threat neutralization versus lethality, maneuvering and closing on an enemy, and multiple engagement.  Add those things in, and the significance of the additional 50% only continues to decrease.  The margin in which the extra velocity within the 14.5" barrel's "effective fragentation range" will truly influence outcomes seems minimal to me as well, in the order of perhaps a half percent if that.  I haven't got data for that, and I doubt you do, either - though I would be interested to see it (with no snarkiness intended) if you do.      

Your assumption seems to be that I prefer "as short as possible" just for clearing rooms.  Indeed, the progress of the discussion and my responses may have inadvertently led you to believe that, however, to me, the importance of length is not "just" in CQC.  While I have said that 14.5" is the longest I would want to conduct CQC with, it is not the only factor in length.  

Having carried rifles of the M16 family for some time now, for hours and days and miles at a time, I would say that in the long run - the shorter the better.  Better for walking, better for riding, just all around preferable.  Here I again depart from a straight comparison - I state only that "I want the shortest weapon that is the most effective in the widest range of situations that I am likely to encounter."  To me, that is a 14.5" barrel.  16" does not even enter into my consideration - if I'm making the next jump up in favor of velocity over length - it will be to 18".  

I am not suggesting that velocity is not good or that it is undesired - I understand your reasoning but do not agree with it, because I feel that the practical value of it is minimal.  And if the impact is minimal, I will sacrifice it for length.    

With regards to weight - I would heartily agree.  Along with "as short as possible" naturally comes "as light as possible."  However, I would qualify that as to say, like barrel length - only insofar as it does not sacrifice capabilities.  In comparison to many - I run a "heavy" rifle, light, IR laser, 1-4x optic, medium contour barrel.  All of those things are more important to me than weight or length.  Another factor, though we're veering even more off course - is balance.  A well balanced heavy rifle can be more comfortable to carry than a light, poorly balanced one.  

In the end - it's not that I disagree with you that the increase in velocity is a fact.  I simply disagree in the significance placed upon it.  I would continue to maintain that in my personal opinion, 14.5" is a more ideal general purpose barrel length than 16", by general purpose meaning not "just" CQC, but a rifle that you intend to carry all day everyday, and might be called upon to fight anywhere from CQC distances to a 600m standoff range, which I would consider to cover both military contexts and most SHTF contexts.  

~Augee

IBTL...

MAHA