223 Remington/5.56 NATO, velocity versus barrel length: A man, his chop box and his friend’s rifle

Hey man, can I cut up your rifle?

I knew that our 300 Winchester Magnum: How Does Barrel Length Change Velocity- A 16″ 300 Win Mag? article would be popular, but it has really exceeded my expectations.  Quite a few readers asked for a similar experiment with the 223 Remington and/or 5.56 NATO cartridges as well.  So after some careful negotiations with my buddy, he volunteered his Remington 700, chambered in 223 Remington for this experiment.

If you search the web, you can find quite a bit of data on 223 Remington and 5.56 NATO ballistics from 20″, 16″ and 14.5″ barrel lengths.  This makes sense since these are the most commonly used in the AR style rifles.  Intermediate barrel length data is somewhat less common.  In this article, we are starting with a 26″ barrel and cutting it back, one inch at a time to 16.5″ and measuring the average velocity with four different cartridges.

This is the test rifle.  It is a factory Remington 700  varmint chambered in 223 Remington.

This is the test rifle. A factory Remington 700 varmint chambered in 223 Remington.  Note the excellent Spuhr mount and Nightforce F1 scope.

For this experiment, we used four different factory loaded cartridges; Remington UMC 223 Remington 55-grain U223R3, Federal XM193 5.56 M193 55-grain ball (the box is labeled both XM193 and M193 and has an 02 head stamp), Winchester M855 (08 head stamp) and Black Hills 223 68-grain Heavy Match ammunition.

The 223 Remington and 5.56mm Nato ammunition used for the test.

The 223 Remington and 5.56mm NATO ammunition used for the test.

Here are the bullets pulled from the cartridges, from left to right, UMC 55-grain, Federal 55-grain M193, Winchester 62-grain M855 and Black Hills 68-grain Heavy match.  Note the tar sealant on the M193 and M855.

Here are the bullets pulled from the cartridges, from left to right, UMC 55-grain, Federal 55-grain M193, Winchester 62-grain M855 and Black Hills 68-grain Heavy Match. Note the tar sealant on the M193 and M855.

Here are the cartridges disassembled.  From left to right, UMC 55-grain, Federal M193, Winchester M855 and Black Hills 68-grain heavy match.

Here are the cartridges disassembled. From left to right, UMC 55-grain, Federal M193, Winchester M855 and Black Hills 68-grain heavy match.

A quick note on chambers and ammunition, 223 Remington and 5.56 NATO chambers and ammunition are not the same or necessarily interchangeable.  223 Remington is a SAMMI specification and 5.56 NATO is a NATO specification.  Without getting overly involved, chamber dimensions are different with 5.56 NATO dimensions being more generous and the 5.56 ammunition running hotter than its 223 counterpart.  In our case, our 223 rifle fired 5.56 safely, however, this may not be the case with your particular firearm.  Remember, only use ammunition that the manufacturer of your firearm recommends.

The rifle is a stock, left-handed Remington 700 with a chrome moly varmint contoured barrel.  The bolt has been fluted and the bolt knob replaced by Kampfeld Custom. The rate of twist is 1:12″. We recognize this is the wrong twist for stabilizing heavier bullets, however, feel the velocity information gathered would be worth the effort of firing the heavier bullets.   It should be noted, prior to testing we were able to shoot some 2 MOA groups with the M855.  The 68-grain Black Hills load opened up to approximately 6 MOA.

The rifle’s headspace was measured at 1.4676+ and firing pin protrusion was .053″.

We ordered the following products from Brownells for this experiment:

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What was our test protocol?

Ballistic data was gathered using a Magnetospeed barrel mounted ballistic chronograph.  At each barrel length, the rifle was fired from a front rest with rear bags, with five rounds of each type of ammunition.  Average velocity and standard deviation was logged for each round.  Since we would be gathering data on 44 different barrel length and ammunition combinations and would not be crowning the barrel after each cut; we decided to eliminate gathering data on group sizes.  Note: we did fire one test group at the end of the experiment with the barrel at 16.5″, you’ll see our results at the bottom of the page.

Once data was gathered for each cartridge at a given barrel length, the rifle was cleared and the bolt was removed.  The barrel was cut off using a cold saw.  The test protocol was repeated for the next length. Temperature was 45.7F.

Test rifle in on the rest with the chronograph in place.

Test rifle is on the rest with the chronograph in place.

No hacksaws this time, we went all in!  The cold saw makes short work of cutting the barrel.  We had to borrow a generator to bring power to the range.

No hacksaws this time, we went all in! The cold saw makes short work of cutting the barrel. We had to borrow a generator to bring power to the range.

Marking the barrel prior to beginning.

Marking the barrel prior to beginning.

Even though there are a lot of sparks, the saw doesn't add much heat to the barrel.

Even though there are a lot of sparks, the saw doesn’t add much heat to the barrel.

While it doesn't look like a finished product, the cold saw leaves a better finish then a hacksaw.

While it doesn’t look like a finished product, the cold saw left a better finish than a hacksaw.

Barrel carnage!

Barrel carnage!

 

Results

Our results are posted below.

Barrel length in inches versus Muzzle velocity in feet-per-second

Rifleshooter.com

Barrel length in inches

UMC 223/55

Federal M193/55

Winchester M855/62

Black Hills 223/68

26

3182

3431

3280

2849

25

3221

3426

3229

2828

24

3211

3409

3188

2804

23

3132

3350

3169

2775

22

3111

3366

3158

2774

21

3090

3305

3117

2762

20

3071

3306

3097

2740

19

3028

3259

3060

2699

18

3006

3202

3052

2679

17

2922

3151

2972

2652

16.5

2968

3187

2992

2632

AVG velocity loss per inch

22.5

25.7

30.3

22.8

Here is the above information presented as a line graph:

223 barrel length v velocity graph

 

Cartridge specific data:

Effects of barrel length on Remington UMC 223 55 grain FMJ

Barrel length in inches

UMC 223/55

SD

Change ft/sec velocity

Change ft/sec velocity from 26″

26

3182

28

25

3221

30

39

39

24

3211

16

-10

29

23

3132

28

-79

-50

22

3111

24

-21

-71

21

3090

20

-21

-92

20

3071

35

-19

-111

19

3028

30

-43

-154

18

3006

31

-22

-176

17

2922

38

-84

-260

16.5

2968

33

46

-214

 

Effects of barrel length on Federal M193 55 grain FMJ

Barrel length in inches

Federal M193/55

SD

Change ft/sec velocity

Change ft/sec velocity from 26″

26

3431

21

25

3426

31

-5

-5

24

3409

39

-17

-22

23

3350

19

-59

-81

22

3366

42

16

-65

21

3305

47

-61

-126

20

3306

24

1

-125

19

3259

39

-47

-172

18

3202

25

-57

-229

17

3151

16

-51

-280

16.5

3187

44

36

-244

 

Effects of barrel length on Winchester M855 62 grain FMJ

Barrel length in inches

Win M855/62

SD

Change ft/sec velocity

Change ft/sec velocity from 26″

26

3280

17

25

3229

24

-51

-51

24

3188

14

-41

-92

23

3169

19

-19

-111

22

3158

27

-11

-122

21

3117

11

-41

-163

20

3097

14

-20

-183

19

3060

14

-37

-220

18

3052

43

-8

-228

17

2972

19

-80

-308

16.5

2992

14

20

-288

 

Effects of barrel length on Black Hills 223 68 grain heavy match

Barrel length in inches

Black Hills 223/68

SD

Change ft/sec velocity

Change ft/sec velocity from 26″

26

2849

15

25

2828

24

-21

-21

24

2804

36

-24

-45

23

2775

40

-29

-74

22

2774

27

-1

-75

21

2762

18

-12

-87

20

2740

14

-22

-109

19

2699

27

-41

-150

18

2679

37

-20

-170

17

2652

19

-27

-197

16.5

2632

18

-20

-217

 

So, what did we find out?

  1. Cutting the barrel from 26″ to 16.5 ” resulted in a velocity reduction of 214 ft/sec with the UMC 223 55 grain cartridge, 244 ft/sec with the Federal M-193 cartridge, 288 ft/sec with the Winchester M855 cartridge and 217 ft/sec with the Back hills 223 68 grain match cartridge.  It should be noted that the 17″ barrel length provided the slowest velocities in for the UMC 223 55 grain cartridge, Federal M-193 and Winchester M855 with velocity reductions of 260 ft/sec, 280 ft/sec and 308 ft/sec with each cartridge respectively.
  2. Utilizing the data from the 16.5″ barrel, average velocity loss per inch of barrel length was 22.5  ft/sec for the UMC 223 55-grain cartridge, 25.7 ft/sec for the Federal M-193 cartridge, 30.3 ft/sec for the Winchester M855 cartridge, and 22.8 ft/sec for the Black Hills 68-grain heavy match cartridge.
  3.  The UMC 223 55-grain cartridge experienced a fairly significant velocity loss when the barrel was cut from 24″ to 23″ of 79 ft/sec, and 18″ to 17″ with a reduction of 84 ft/sec.
  4. The Federal M-193 experienced a significant velocity loss between 24″ and 23″ of 59 ft/sec, 22″ and 21″ of 61 ft/sec, 19″ and 18″ of 57 ft/sec, and 18″ and 17″ of 51 ft/sec.
  5.  The Winchester M855 experienced fairly significant velocity loss as its barrel was cut from 26″ to 25″ of 51 ft/sec, and 18″ and 17″ of 80 ft/sec.
  6. The Black Hills 223 68-grain heavy match was lost velocity at a fairly consistent rate.  The largest decrease in velocity resulted from the barrel being cut from 20″ to 19″ with a loss of 41 ft/sec.
  7. Of the 220 test rounds fired, we logged 6 light primer strikes on the Federal M193 and 1 on the Winchester M855.  All of these cartridges fired on the second attempt.  Firing pin protrusion was adequate, .053″.  My guess is these light hits were related to the strength of the firing pin spring.

How did barrel length affect exterior ballistics?

We ran each load for 26″, 23″, 20″ and 16.5″ barrel lengths out to 600 yards, a reasonable distance for this cartridge.  These figures assume a 1.75″ height of the optic over the bore and weather conditions of 59F.

photo 1 photo 2 photo 3

photo (1)

 

You’ll notice minimal difference in external ballistics out to 300 yards, but approximately 20″ of additional drop in the shorter barrel at 600 yards.

How did barrel length affect Maximum Point Blank Range (MPBR)?

Since the 223 Remington is a popular hunting cartridge, we also worked out the maximum point-blank range (sometimes referred to as maximum point blank zero) for each barrel length with the given load assuming a 8″ vital area.  We selected an 8″ MPBR for comparison purposes, since this was the same size vital area we used for the 300 Winchester Magnum barrel length article.

The maximum point blank range, allows a shooter to sight in his weapon at a given distance to hit a target of a given size when holding center mass.  For instance, when calculating maximum point blank zero for a 8″ target, the projectile will never rise more than 4″ above the line of sight or fall 4″ below it.  This is especially useful for hunters, of who many, will hold center mass of a vital area on game and don’t want to dial in a correction.  Our calculations assume a 1.75″ sight over bore height.

223/5.56 Maximum Point Blank Range (MPBR) on 8” Target

Barrel length

UMC 223 55

Federal M193

Winchester M855

Black Hills 223 68 HM

26”

322 yds

343 yds

340 yds

305 yds

16.5”

302 yds

322 yds

313 yds

284 yds

Change in MPBR

20 yds

21 yds

27 yds

21 yds

You’ll notice the change in MPBR averages 22 yards across the cartridges.

Closing

What are the possible sources of error in our experiment?  You’ll notice an increase in velocity despite a decrease in barrel length in a few instances in the data above.  I would attribute this to a relatively small sample size. Most of the other experiments I have read about, use three rounds of each combination.  Only one used ten, but they did not provide data and the claims seem to be dubious in nature.  We shot five rounds for each combination. We had certain time constraints, budget limitations, etc.  Gathering the data takes two guys and an entire day. Processing and writing about it takes much longer.

How did we improve this experiment over the last one we did? Compared to the 300 Winchester Magnum: How Does Barrel Length Change Velocity- A 16″ 300 Win Mag?  experiment, we did do a few things differently.   First, we used a chop box that didn’t beat up the gun nearly as much as a reciprocating saw or hacksaw.  The cut was more precise than the previous methods we had tried.   While it required us to drag the saw and the generator to the range, it was certainly worth it. We also introduced four different types and weights of ammunition.  Finally, we placed the chronograph at the same point, 2″ from the muzzle at each barrel length to ensure our data was recorded at the same spot.

Why didn’t we cut and crown the barrel at each length?  Short answer is that it takes too much time.  For the long answer, read on.  I’ve read about this criticism a few times in the 300 Win Mag article, and while I think this would be beneficial for accuracy testing (which was outside the scope of this experiment), professionally re-cutting the crown would have added a tremendous amount of time to the experiment.  My lathe is in my basement; a 2-hour round trip from the range.  Counting set up time at the range, this would have added a minimum of 30 hours to the overall time required to complete this experiment.

Do you think you lose a lot with a short barrel in a 223?  In most applications, I think the shorter barrel has a lot going for it: easier maneuverability, quicker handling and a lighter rifle; all at a fairly small velocity loss. For special applications, like building a 600 or 1,000 yard F-class T/R rig, I would certainly go long (like most guys do), but for your average rifle and rifleman, shorter seems to work well.

In some of your other short barreled rifle articles you mention that shorter barrels look cooler, do you still believe this?  Yes, I do.  Short barrels look much cooler.  This is a fact, proven again and again.  A friend commented that you should enjoy the way your short barreled rifle looks, because your hearing will be gone and your sight will be your only sense left.  Maybe he is right.

Have you seen similar experiments with a 223 Remington?  Yes, three that are noteworthy.  Posted in 2001, Accuratereloading.com used handloads and documented barrel length from 22 to 10″ long, you can find it here.  Ballisticsbytheinch.com used 45, 50 and 55-grain factory ammunition from 18″ to 3″ in length, you can find that article here.  A friend sent me a link to this article using four different guns, 3 bolt action and 1 gas gun.

Did you shoot any groups?  Yes, a few.  We did shoot a couple of sub MOA groups with the 16.5″ barrel.  I posted a pic of the group and crown below.  Pretty interesting, huh?

We fired this 5-shot group with Federal M193 at 100 yards with the 16.5" barrel.  It measured .901.

We fired this 5-shot group with Federal M193 at 100 yards with the 16.5″ barrel. It measured .901″.  Not too shabby!

This is the crown that produced a sub MOA group... it is smoother then our hacksaw groups, but still not ideal.

This is the crown that produced a sub MOA group… it is smoother than our hacksaw groups, but still not ideal.

Why didn’t you use a 1:7 or 1:9 twist barrel?  We would have liked too, but didn’t have one available.  I don’t believe this would have had an impact on velocity figures.

Why didn’t you spend more time discussing the differences between 223 Remington and 5.56mm NATO?  Dude, it’s been discussed ad nauseam in every internet forum and blog in the gun industry.  I’ll pass.  I will take a wild guess that in the comments following a link to this article on any forum or blog, someone will mention that they are different and wonder why I didn’t use a 1:7 twist.

Did the rifle get noticeably louder? Yes, especially with the M193 at 17″ and M855 at 16.5″.   The other two loads weren’t as obnoxious at the shorter lengths.

Whats next?  I am considering a 338 Lapua and a 308 Winchester article.  If I do, I will post a link here.

I hope that the data presented here was helpful.  Until next time, stay safe.