AR15.Com Archives
 Ideal barrel length for .223?
SMProud  [Team Member]
12/22/2001 5:17:13 PM EST
I've been wondering what the ideal length for a .223 bullet is. The 14.5" barrels with break seem to be gaining popularity. Does a .223 loose much accuracy in a 14.5" barrel compared to a 16"? I know a .45ACP optimal length is 11", what is the optimal for a .223?
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SJSAMPLE  [Member]
12/22/2001 5:23:02 PM EST
The 14.5" would be great, if it wasn't for the paperwork, the $200, and the wait (although I'm still considering it). If you want a fast plinker/"tactical" thingy, start at 16" and ask yourself if 14.5" is worth it to you (aforementioned issues AND lower muzzle velocity). For now, my 16" works well for me.
mattsd  [Member]
12/22/2001 5:33:55 PM EST
im sure he means the M4 barrel (14.5 with pinned comp or flashhider)it dosent really loose accuracy at that leanth, it does, however loose range. not sure how dramatic, but if your smart enough to have a 10- inch barrel, dont expect to outshoot one of treetops .22s
Big_Bear  [Team Member]
12/22/2001 6:58:27 PM EST
A short barrel loses zero accuracy over a long barrel. The difference is the shorter sight plane that is harder to shoot accurately, one of the reasons a rifle is inherantly more accurate than a pistol.
5subslr5  [Team Member]
12/23/2001 5:04:16 AM EST

Originally Posted By Big_Bear:
A short barrel loses zero accuracy over a long barrel. The difference is the shorter sight plane that is harder to shoot accurately, one of the reasons a rifle is inherantly more accurate than a pistol.



And don't forget the loss of "V" locity.
After all the .223 is an SCHV round and you've got to have at a minimum 2500-2600 fps for the round to be properly effective. (Small Caliber High Velocity = SCHV)
14.5" plus suppressor is minimum barrel length needed to achieve these numbers.
5subslr5  [Team Member]
12/23/2001 5:31:28 AM EST
Answer to your actual question; in my opinion 18"+suppressor/brake is optimal.
Should bring your muzzle velocity to around 3,000 - 3200 fps.
AlanD  [Team Member]
12/23/2001 6:05:23 PM EST
It depends upon the function of the rifle and what you want its effective range to be. If the rifle is to be used against moderately large targets (such as man), then you want the bullet to impact (ideally) with a velocity of at least 2700 fps to achieve maximum wounding potential. Then, use that range to determine the barrel length required to achieve 2700 fps at the required distance. For example, if you want an optimal effective range of about 100 yards using M 193, a barrel length of at least 16 inches is needed to retain 2700 fps at bullet impact.

Several notes regarding the above statements. 1. There may be other factors to consider, such as if iron sights are to be used and a longer sight radius is needed to increase accuracy of aim. 2. M 193 certainly may be lethal at velocities below 2700 fps, but the wounding potential is potentially reduced. 3. I currently have no velocity charts available, so my example is an approximation. 4. The initial velocity and composition of the bullet will affect the above calculation.
Shooter505  [Team Member]
12/23/2001 6:12:46 PM EST
Can someone tell me why the military choose the 14.5 inch barrel? Why not go with the 16 inch.
SJSAMPLE  [Member]
12/23/2001 6:17:26 PM EST
I think the military went with 14.5" because it allowed the standard carbine length handguards to be used on a rifle that could still mount a bayonet. The 16" barrel is too long to allow a mounted bayonet to engage the bayonet lugs, while 14.5" works.
Bostonterrier97  [Member]
12/23/2001 6:41:18 PM EST
I would stick with 20 inches: .223 effectiveness is dependent on bullet fragmentation to create large permanent wound channels. A very short barrel will significantly decrease the already short effective range for the .223 round.
5subslr5  [Team Member]
12/23/2001 7:00:41 PM EST

Originally Posted By SJSAMPLE:
I think the military went with 14.5" because it allowed the standard carbine length handguards to be used on a rifle that could still mount a bayonet. The 16" barrel is too long to allow a mounted bayonet to engage the bayonet lugs, while 14.5" works.



My "I learned something" for the day.
Thanks
5subslr5  [Team Member]
12/23/2001 7:05:03 PM EST

Originally Posted By Bostonterrier97:
I would stick with 20 inches: .223 effectiveness is dependent on bullet fragmentation to create large permanent wound channels. A very short barrel will significantly decrease the already short effective range for the .223 round.


I don't want no duel with no B. Terriers.

However, as an example the ArmaLite AR-18/180 has an effective range of about 500 yards with an 18" barrel and roughly 3200 fps muzzle velocity.
I guess what you mean by short range matters.
ARLady  [Member]
12/23/2001 7:32:30 PM EST

Originally Posted By 5subslr5:

Originally Posted By Big_Bear:
A short barrel loses zero accuracy over a long barrel. The difference is the shorter sight plane that is harder to shoot accurately, one of the reasons a rifle is inherantly more accurate than a pistol.



And don't forget the loss of "V" locity.
After all the .223 is an SCHV round and you've got to have at a minimum 2500-2600 fps for the round to be properly effective. (Small Caliber High Velocity = SCHV)
14.5" plus suppressor is minimum barrel length needed to achieve these numbers.



and let's not forget to take into account the loss of velocity (and energy). once you get below the 2500-ish fps threshold, the bullet's ability to transfer most of its energy (fragmentation and the like) to the target is lessened. so even if muzzle velocity is at or above the threshold velocity, it doesn't mean you're going to get the desired results at 500yds.

and the shorter barrel gives you less muzzle velocity than a longer barrel all else being equal which translates into (slightly) shorter effective range.
Big_Bear  [Team Member]
12/23/2001 7:57:32 PM EST

Originally Posted By Bostonterrier97:
I would stick with 20 inches: .223 effectiveness is dependent on bullet fragmentation to create large permanent wound channels. A very short barrel will significantly decrease the already short effective range for the .223 round.


Not exactly. When you mention bullet fragmentation in reference to this caliber, may I assume you're talking about Martin Fackler's research data on military bullets, specifically M193 ball and M855 ball FMJ rounds? Not all .223 is the same and not all .223 fragments. Much depends on bullet design, so a blanket statement covering the "effective range for the .223 round" is incorrect. However, I agree with you that a 20" barrel is better if terminal ballistics is a concern.
tatjana  [Team Member]
12/23/2001 8:32:46 PM EST
Don't ask "what's the best length" and then apply that to a situation. Understand the use of the rifle and apply that to barrel length.

I have three rifles for three purposes. My general purposes rifle is a 16" Bushmaster. I picked this because I have a smaller frame and its much easier for me to assume a shooting position from the ready under time pressure and put rounds on target. I also wanted a lighter rifle and was worried mostly about putting rounds in targets inside of 200 yards. This is because for me anything outside of 200 yards is either an escape and evasion problem or a job for 7.62 delivered from my HK91. I prefer milspec M193 ammo (for a bunch of reasons) and since I put a bottom end on effective velocity of around 2600fps that keeps things at around 180 yards out of a 16" barrel.

There is no "best" length in general. Rifles are tools. There is no "best screwdriver" either.
Danny7  [Member]
12/23/2001 8:49:19 PM EST
God Tatjana,
I am becoming your private fan.
When you speak, I listen.

Hey Tatjana, quick question.
Does IMI SS109 have any accuracy problems compared to M193 by winchester. Shot new stuff for first time and not happy.

Could have been a bad day but we shall see. Also this is why you shouldnt play with match ammo unless you have a match or need to investigate something.


z71rat  [Team Member]
12/24/2001 8:04:37 AM EST

Originally Posted By tatjana:
There is no "best" length in general. Rifles are tools. There is no "best screwdriver" either.



Very well put there tatjana........ Me like.

DK
tatjana  [Team Member]
12/24/2001 11:59:52 AM EST

Hey Tatjana, quick question.
Does IMI SS109 have any accuracy problems compared to M193 by winchester. Shot new stuff for first time and not happy.



I'm not a huge fan of SS109 or M855. It was adopted to make SAW fans happy, not to function ideally in the M-16 or AR15. I think they are difficult to manufacture well, they often aren't balanced and I prefer a simple round (M193). Remember that government contractors manufacture this stuff.

Combat_Jack  [Team Member]
12/24/2001 3:43:42 PM EST
Barrel length has little to do with acuracy. A 14.5 inch barrel is as accurate as a 20 inch barrel, assuming same contour. Some high power shooters have done experiments with 14 in barrels. The bottom line is: barrel contour is more important than length if accurcy is your concern.
brouhaha  [Team Member]
12/25/2001 7:33:10 AM EST

Originally Posted By tatjana:
I think they are difficult to manufacture well, they often aren't balanced and I prefer a simple round (M193).



I've heard and seen of many cases where the steel core of SS109 isn't formed correctly. This leads to an imbalance, which, of course, leads to a loss of accuracy.

There is also the problem with the round's extra weight...out of a 14.5" barrel, the SS109 round loses a critical amount of velocity, which means that it is less effective than a M193 at the same distance.

I'm sure Tatjana can go into more detail on this than me.

I don't know if it would be possible to load the stuff a little hotter to make up for this or not.
BlackandGreen  [Team Member]
12/25/2001 8:27:52 AM EST
GEEESH!.........Rifling?........................bullet wieght?.............
Master_Blaster  [Member]
12/25/2001 8:41:11 AM EST
16", fluted hvy bbl., IMO. Besides, who really needs a bayonet? Got my Dieter CQD Mk I LE & SEAL SOG 2K for up close & personal encounters.

Blaster out.
Erasmus  [Member]
12/25/2001 3:08:51 PM EST
I see you are discussing short barrels.

My "ideal" barrel is as long as practicable.
Troy  [Site Staff]
12/25/2001 7:55:54 PM EST
www.ecis.com/~mraudio/AR15_Ammo_FAQ.htm

-Troy
5subslr5  [Team Member]
12/26/2001 7:23:23 AM EST

Originally Posted By Master_Blaster:
16", fluted hvy bbl., IMO. Besides, who really needs a bayonet? Got my Dieter CQD Mk I LE & SEAL SOG 2K for up close & personal encounters.

Blaster out.


But how could you ever participate in those frequent "drive-by" bayonettings ??

(I do like 16" fluted.....)
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