Tag Archives: M855

Question and Answer

This is a LooseRounds.com Q&A session.  If you have a firearms related question please email it to QA@LooseRounds.com. We will post the your questions anonymously and give you our answers.

We get a lot of smaller  questions sent to us weekly.  So today I am going to rapid fire answer a few of the easiest to get  the info out to those who want it.

What caliber of ammo was used in the m40 in viet nam?    7.62 NATO  M118 special ball

5.56 green tip vs car door?  Yes, M855 will go through a car door

What ammo for 1:7 twist?   Any ammo is fine for 1/7  despite what you may hear or read otherwise, 1/7 will shoot as low as 40 grain all the way to 90 grain

winchester unertl scope? Winchester did not make Unertl scopes, Unertl is the maker not the model. Winchester did sell scopes but they have another name and were used some in WW1 and 2

Does a colt le6920 have a firing pin spring? No,  the colt 6920 is the closest you can get to a military M4 and is milspec other then  the barrel length and full auto. The 901 does use a firing pin spring.

colt 901 dry or lube?  Lube. all guns need and work better with lube. Always.

does colt rail gun come with night sights? No, the USMC  rail gun does, not the current civilian model. The USMC model will be sold in 2013


How are Super Sniper scope?  SWFA SS scopes are generally considered good for the money.  Their HD line receive excellent reviews.  I owned a side focus 10x and thought it was very good for a cheap scope.  I also owned a 5-20 and thought highly of it.  However SWFA has been criticized for how they have been handling some sales and preorders.

how to modify 25 ammo for better performance?  We highly recommend against modifying factory loaded ammunition for self defense.  Modified ammo can have various issues from poor feeding to blowing out the center of the projectile when fired, and leaving a ring shaped section of the bullet in the neck of the barrel.  As for .25 ACP, often a round that has good penetration is recommended for self defense.  A large part of ammo selection for the .25 is finding what will work reliable in your firearm.  The various 50gr full metal jacket rounds from the major ammunition manufactures are what is often recommended.


Dead batteries, LaRue, and M4 zeroing.

I went on a trip to Michigan recently.  During this trip I ended up using my hand held light for 40 minutes one night.  It still boggles my mind that some people feel it is not necessary to carry a flash light, however that is beside the point.  This use drained the battery in my light, so in the morning I went to replace the battery.  Turns out both Panasonic brand batteries I bought with me as backups were dead.

So from now on I am going to check my spare batteries before I pack them.

LaRue has announced an upcoming price increase.  At the 1st of next month prices will jump 7.5 to 12.5%.  While I understand that prices will change, and that change is normally upwards, it saddens me to hear of this.  I already know to many people who have bought far inferior gear just to save a few dollars.  I hope that this increase in price won’t discourage new buyers from buying LaRue products.  If you were planning a purchase from LaRue, might as well try and get it in before the price increase.

Yards vs. Meters.  Turns out there really is a difference.  In the USMC we often used the two terms interchangeably.  However yards are not the same as meters.  Currently the Army uses a 300 meter zero on their M4 carbines. This is accomplished by firing point of aim (POA) point of impact (POI) at 25 meters with M855 ammunition.   This puts the round about 7 inches over POA at 175 meters, and 7 inches low at 350 meters.

Zeroing at 300 yards with the same ammo gives you a max hight of 5 inches over the point of aim (at around 175 yards), then the round drops to 5 inches below point of aim at 350 yards.  However at 350 meters the round is about 9 inches below point of aim.  I have not double checked the numbers yet, but it looks to me that the distance numbers on the detachable 6/3 carry handle for the M4 are a better match if you are shooting in yards instead of meters.

For many civilians, the 300 yard zero may be more practical then the 300 meter zero due to the flatter flight path under 300 yards.  Most ranges are measured out in yards, so a reduced 300 yard zero could be had by having your impacts 1/2 inch low at 25 yards or 1 inch high at 50 yards using your 300 yard sight setting.  As always, when possible confirm your zero at distance.

One last thing, please don’t try to get a 300 METER zero by shooting at 25 YARDs.  This is closer to a 350 meter zero, and puts your rounds about 10 inches high at 200 meters.  If you want a 300 meter zero on the M4, shoot at 25 meters.



Guns and Ammo posted an interesting article on the Army’s new M855A1 “green” ammo.  This confirms prior rumors of it being high pressure and inaccurate.  However there is no mention regarding the rumors that M855A1 fouls more then M855.

Sadly, it sounds like there is little good to say about the new M855A1 round.

Testing the 5.56mm MK318 MOD 0 / 5.56 SOST ammo

The 5.56 SOST  is the ammo currently being used by the USMC and other troops in the GWOT,  it has not been available for the public to buy for very long so I, like a lot of other people have been curious about how it performs. The round was designed to  have better terminal performance and accuracy from short barreled rifles with a muzzle velocity of 2925 fps from the 14.5 inch M4 barrel.  The round is a OTM,  this is important to remember as it is not the same as a hollow point.  It does however, offer up better performance and is barrier blind. The bullet itself has a thick copper base and a lead front end with the usual open tip that results from the process of making the bullet.  Also present are the rings seen around the bullet much like a barnes triple shock X.  A lot of people assumed and still do that the SOST is a barnes solid copper TSX, but it is not.

After getting my hands on some of the ammo I decided to test it for accuracy first. Since the ammo is intended for combat weapons, I chose to use my Colt 6940  with milspec barrel with 1/7 twist. I did put a Leupold 18x target scope on the carbine though so i could get all the accuracy out of it I could.  I fired 2 strings of 5 shots at 1 inch dots and one string of 10 shots of M855 to compare it to the common military load all at 100 yards. It was around 1100 AM , sunny with a  2 oclock 18 MPH wind.

Other then the normal 1st round flyer you usually get from hand cycling the action as opposed to letting the recoil operate and chamber  the next few rounds, the ammo showed some  great potential. The group on the left  was a little worse due to my own bad trigger work and lost concentration on one shot, but still pretty good considering. Now I know some claim  5 shot groups tell nothing, but if you over lay to  strings you get a pretty good idea  and you keep barrel heat down and mirage off the barrel messing with the scope.

After shooting the groups I decided to test out how the round matched the trajectory of the M855 since that is one of the things the SOST round was meant to have in common with the green tip. Out to 300and 400 yards  the SOST did match the BDC of my TA31F  ACOG and zero of other scopes and Aimpoint RDS I had on hand zeroed for the green tip. Also when comparing the position of the groups in relation to the aiming points, you can see on paper that the zero held very close for both rounds.

Now, the real surprise for me, was how good the lot of M855 I shot turned out to be!  Many gun board expurts and gun magazine expurtitions will gladly tell you how terrible green tip is in the accuracy department along with its many other flaws , makes it  slightly more useful then tits on a boar hog. After getting the carbine hot  after some drills using the SOST and playing around, I fired off 10 rounds fairly quickly  with the Colt/18x combo.  The results left me a little surprised, rarely have I seen green tip shot for accuracy  with sand bags, a table and a target scope further then 50 yards. And I do not recall having seen any pictures of it doing as well in a true 100 distance group.  I shot the green tip with all seriousness and the same concentrated effort I did with the SOST and the results were pleasing and a little surprising to me.  I have never taken the green tip seriously  enough for my own needs in the accuracy department so this will indeed lead to more testing of the M855 if for no other reason  then to see if this was a fluke.

Now I do not mean to sound like I think green tip is crap, I have seen some  good performance out of it at longer ranges on coyote size targets and even man sized targets. But on the other hand, I have seen some terrible accuracy from it too. Of course lots and different MGGs have as much to do with it as anything, not to metion the different shoots and the quality or lack of  in the guns used.

Back to the SOST, I think its a pretty good round from what I can tell. It is not MK 262 or TAP 75 gr. But for general issue to everyone, it is an iprovement in my humble opinion.  I have not shot anything living with it yet, but I will. Also, in the next few weeks I will test it though a few “barriers” like auto glass, wood, and wall paneling. Hopefully I will get to shoot through some auto doors as well.  I would not use it in my own house if over shooting is a issue, but I would use it for anything else at this point if you can find enough for SHTF bulk storing. And you have the benefit of practicing/training with M855 and still being able to shoot the SOST without a zero change. At this point I can not say it is better then any MK 262 top load in accuracy, but it is not meant to be, but, it is better then M193 by a long ways and it shows the ability to shoot a lot better the M855 and even if it just matches it in accuracy you still have the benefits of better terminal performance and barrier penetration while still holding together to hit the target behind if power point presentations can be believed. Hopefully my future testing will offer at least a tiny sample to help prove or disprove the new round.