The 5.56MM Service Cartridge





Ever  since the  5.56 service round was adopted over 50 years ago, its reputation has had its ups and downs.  We have went from the 55 grain M193 FMJ round to now having what seems to be a confusing amount of bullet weights and designs and with every different bullet we get a different purpose for its use.  Over last 15 years especially  it has become the general purpose all around work horse for most of us. Yet while most shooters will pay lip service to that fact, few  seem to actually use it to its full potential.



As the market does what it does best, we get more and more rifle rounds. We get some rounds with a lot of possible uses to some that have very limited uses. With so many choices it was natural for shooters to start thinking up, and having made, guns to fill certain specialized roles. Sure it’s fun to lay awake in bed at nigh  while your mind specs out some “idea” rifle for some such purpose or another. Of course that new beauty has to have just the right round for it. Something new  that on paper has the ability hit at range and deliver impressive terminal ballistics for when the _____ happens, said person will have the best tool.

That is all a lot of fun and everyone has or will do it at some time or another even if its just a day dream.  The reality is that most of us ( and I am mainly addressing people who train fairly seriously) use the 556 in a variety of carbines or rifles, for the bulk of our rifle  training.

The AR15 chambered in 556 has become the general purpose rifle for the vast majority of people. It is just a fact if  no other reason than that is what most of them  are made in.  Of  course it is not as simple as that though, but it will do as a starting point

With all that in mind there are a few other things to consider. Things that may help strip away all the zombie fantasy and late night tinfoil hat delirium. The 556 is the service rifle cartridge. It is what the US military uses and will continue to use for the far future despite the hopes of DC lobbyist.    This gives us huge advantages for the round. The military does not use anything they do not test, study and develop and continue to at least consider improving through out its service life.  We saw this with the 7.62 NATO round and still are.  Same with the 556.  We have went from 55gr ball. to things like the SOST, AA53 and now the dubious M855A1.  The spin off effect of military adoption is civilian use and interest.  Not only do we have access to all but a few military rounds, but we have use of even more and better variants and  specialized loads.


This seemingly endless variety makes the AR15 rifle or carbine extremely useful. We have now been seeing that in practice for a few years now. From military use we have seen the rise of the DMR concept AR. Something that in the past many thought had to be a M14 type weapon until that gross misconception was finally put to rest. We also have the MK12 MOD 0 the MOD 1 and now MOD H. All of which are essentially sniper rifles. The USMC has been using the HK IAR for a while now  as the automatic rifle  and now  it is starting to get the role of the DMR.  Of course the 556 service round has been used in the M249 SAW and all its versions, and of course the service rifle and carbine.

The round’s versatility really shines in the non-military world. At one point it was thought of as little more than something to shoot a ground hog with. And most varmint shooters probably would have stuck to the .222 Remington for that.

Things have certainly changed.  A huge wake up call for most serious competitive shooters was the year the US Army Marksmanship Unit took their AMU M16A2s to the National Matches and trounced the USMC’s   NM M14s in 7.62. The civilians shooters had already started to use the 556 for service rifle etc, but the AMU dumping the M14 and the 762 was a real wake up call for a lot of other people. Here was a round that before was not even thought about for such things now taking over.


Back then, few of the serious shooters I knew would  have imagined the round going from the jungle  spray and pray to belted machine gun ammo, to being used in some of the worlds best precision sniper rifles. Never mind  the idea of people in the south and west using the round for easily taking down 300 pound wild hogs.  The service cartridge is seeing improvement continuously  and yearly we get new new loading with ever improving bullet designs and higher quality.

lets think about the service round in more  practical terms for defensive and military use. In the past competitive shooting was a way to help train citizens in the use of the service rifle and cartridge. It was a way to have fun mastering the rifle in preparation for the day those citizens would have to  use those rifles to defend the nation.  Boy Scouts practiced , college and high school shooting teams and the NRA all had events to help get people ready for that potential. Other countries of the world had and still do have a tradition of using their respective  service rifle  in  regular events to keep skills up with the weapons they would be handed if war was to ever break out.   Ostensibly, we carry this on in service rifle matches but it has strayed from its original intent.  The closest we see to this tradition is the various “carbine classes”  the more serious and dedicated among us go to and pay for privately and the Appleseed training that is put on by volunteers that starts  out from basic marksmanship with a large does of other things that are marginally useful.

It used to be in the years past. All of this was done with the service rifle and cartridge and that is a huge strength and advantage from the purpose of this post.  Everyone wants to have something unique to them to set them apart or to conform to their own tastes. And that is fine  as Pat Rogers says,”on a warm day  where huge puffy white clouds slowly float through and impossibly blue summer sky” but in the vent of a major world changing event to our country  where everyone  who can fire a gun if needed, it is much better if everyone capable person is already very familiar with the service round and rifle.

It have always noticed the amount of shooters who are willing to spend a lot of time and money training with their 556 carbine in training classes or locally in some form or another and if something happened, would use their carbine if they can possibly get to it. They may train and practice to a max of 200 yards but beyond  is the end of the known universe for them.

Many of them have a special beloved sniper rifle or long range precision rifle in some very specialized high performance round.  Few of them ever consider practicing with the same gun they would run to if they had to be in a gun fight.  The US military does not get to  decide to use a 6.5-284 or a 300BLK .  They use the 5.56. service round and they should be able to use it to its full ability and have confidence in it.

Even now the exploits of famous military marksman are told and re told into legend and it is a real shame so few really aspire to have enough skill to be just as proficient with their  rifles as those guys from the past.   SGT York used just his service rifle and cartridge just like the Marines of WW1.   Of course there are feats of  skilled men with  astonishing marksmanship and hellishly long shots from recent years, but mostly they are sniper who are expected to be the ones to pull it off with their special tools.   I’m sure there are stories of some soldier or Making a impressive shot at long range with an A4 or M4, but most of us don’t hear about it.



I have made an effort over the  years to show what rack grade rifles will do with standard service amm0.

AR15 At 1,000 Yards (Can a rack grade AR15 and M855 make 1,000 yard hits?)

Using a rack grade M16A2 upper on a semi auto lower and M855 and the MK 262 round , I made my best case that regular equipment can shoot to 1,000 yards and make actual hits on a man. It still frustrates me that so many think of it as some great miracle or gimmick. It is not. It is doable and within the ability or anyone who is a competent rifleman.  Even shooters on the mid level with a little practice can see hits at 800 yards with the AR15 rifle, or carbine and the 556 round using the standard issue ammo. It does not require  bank busting custom rifles. It does require practice and use.

Accuracy of the Milspec AR15 Carbine barrel

I have owned and/or used a wild amount of specialized rifle rounds for short and long range shooting. Everything from the .17 Remington to the 50BMG but I come to the decision 10 years ago to focus on using the service cartridge. I wanted to get everything out of it I could. To see what it would do and to hopefully open the eyes of its detractors and people who just had no idea.   I use it in the service rifle in one form or the other.   I do use specialized version of the Ar15, but always in the 5.56 round.  the beauty of that combo is  that you are always using and getting better with the round and the gun due to the controls and ergonomics of the AR15 almost always exactly the same on every one of them.

There is a lot to be said for regular use of the 556 round not only for 50 yard carbine work, but for  long range shooting.  As i said it is the round almost all of us use as a self defense carbine round.  Being able to use it well and to hit at long range makes you better at shorter ranges. it gives you the ability to make hits at ranges maybe the other guy can not hit  you from. For those in the military, it is what you are going to be handed  so why not master it completely ?

I like the idea of all serious minded shooters being very familiar with the service round. In my fantasy idea world the country would be a nation of rifleman all competent with the service rifle and round.  All serious shooters would be able to take a rack M4 and make a hit on a man sized target at 500 yards on demand, and be able to take prone shot with an A4 and hit at 800 yards. It would be as if everyone was a designated marksman.   That would have to be a valuable resource to a military in time of need. That was the intent of leaders past. To keep a nation of rifleman.

In the event of a major emergency where the country  was in danger, or a break down of things having a population to draw from  that could be handed an old surplus M16A1 or A2 or even a new M4 would be a huge advantage.  If things happened to be bad enough, and the gov collapsed, local communities or state gov would have the ability to arm people with rifles and ammo from what used to be the federal government for protection.  Laugh if you want, but who knows anymore?  The world has taken a strange turn, black is white and up is down these day.



Besides it use usefulness for martial purposes, the service round has  a hat to wear for about anything you want to use it for. I use the 556 for pretty much everything anymore except pistol use ( and it is even used for that by some people ) or the very limited times I need a shotgun.   other than that, I use the 556 almost exclusively in rifles these days .  After years of use and pushing it to its limits, I have learned that it does everything I need from 0 to 1,000 yards with just simple changing of the Ar15 variant.  To go along with that I also use the Ar15 in one form or another for 99 percent of my rifle or carbine use from  traini9ng to competition  to small and medium game  to sniper training.   When I got a Mk12, I retired all my bolt guns from any thing other than the rare use or for friends who like to shoot them.  the Mk12 in 556 using 77 grain MK262  fill all of my long range precision needs.


Before the Mk12 I used the Colt Accurized Rifle for long range. It played multiple roles for me but the 24 inch barrel limited it for everything I wanted. the Mk12’s 18 inch barrel is handier and the 1/7 twist gives more variety where as the CAR ‘s 1/9 twist  would not allow me to use 80 grain sierra bullets.

My friends and I used the Colt Accurized Rifle  HBAR Elite for many years for precision rifle use from its first introduction in the mid 90s.


With both of the precision Ar15s, the ammo is essential to get the most out out of them. Even with that need  there 556 is available in the military match loading.


The service round is our most useful cartridge. With practice it will give you much more than what you may only be seeing at “carbine class “ranges. It is capable of some very impressive results.  With regular use shooting at long range, hunting, urban sniping for LE and general training and hunting  you will grown in skill and confidence with it and see just how valuable the 556 is and become better ready for the possible future day when you have to use to for much more serious purposes.