Federal M vs XM (5.56) and XM193 vs XM855

X vs XM…XM193 vs XM855?!?

Learn the confusing differences between Federal’s X and XM designations of their 5.56 ammo, as well as the differences between XM193 and XM855 rounds.

Plus ammo recommendations!

Federal 5.56 M193 vs XM193


In a nutshell, “M” by itself means that it meets military specification (mil-spec) while “XM” means it does not.

But just keep in mind that mil-spec is very stringent and even a small thing out of specification can lead to tons of ammo being rejected.

And overwhelming consensus/review is that XM193 is some fine shooting ammo.  But for some sleep-inducing reading pleasure, you can check up the mil-spec standards of M193 for yourself.

Federal must have gotten so many questions that they put up a site that describes XM193.  Emphasis is done by me.

XM193 product is first run, first quality product manufactured at the Lake City Army Ammunition Plant for Federal Cartridges and is made to Federal specifications typical for commercial ammunition.

All XM193 product is the same regardless of the sku or part number. (ie. XM193C is the same as XM193F, XM193CBP and etc … )  The only difference is the package configuation.

Sadly the page is now down (as of 2016) but here is the link (slow load) where I grabbed a cache of it from 2012 and a screenshot of the cache below.

Federal XM193 FAQ
Federal XM193 FAQ

I think they were just trying to calm fears that it was inferior ammo for the shooting public.

If you’re trying to be technical…I guess it is inferior to mil-spec, but still fine enough for commercial specification.

And to make it more confusing, the M vs XM only applies to Federal/American Eagle.  Other manufacturers such as PMC use the M193 designation.

As far as I know, it’s really good ammo but just because it’s called M193 doesn’t mean it’s mil-spec.

So Can You Buy M193?

Once it is designated M193, it should be going to the military so you’re going to have a hard time getting the “real deal” without possibly breaking some laws.

We do not recommend that.

But we do recommend the below ammo:

M193 vs M855

The M193 cartridge is a 55 gr lead core surrounded by a copper jacket (FMJ-BT, full metal jacket with boat tail).

While the M855 “green tip” cartridge is 62 gr and has a steel core “penetrator” at the tip which helps it go through barriers more easily (also FMJ-BT).  You can see the lighter gray of the steel below.

M855 Cutaway, Bearingarms.com
M855 Cutaway, Bearingarms.com

To make things a little more confusing, you might also see SS109, which is more often the designation of the bullet projectile but for some non-US ammo manufacturers, it could refer to the entire cartridge.

Green Tip SS109 Projectiles
Green Tip SS109 Projectiles

Should I get M193 or M855?

You’re probably thinking…”penetrator” sounds pretty badass and it goes through barriers more easily…so I need it.

In reality, M193 does a better job against soft targets under 100 yards since it fragments more than the M855 which has the steel core.  After that length, the M855 seems to catch up.

M193 Fragmentation, Ammo Oracle
M193 Fragmentation, Ammo Oracle

Also, keep in mind that the barrel twist of your rifle will also dictate how well the heavier projectile will fair.

If you have a 1:7 or 1:8 twist, it will be fine, but if you have the more commercially popular 1:9, you’re better off sticking with the M193 55 gr.

Ideal Bullet Weight vs Twist, Shooters Log
Ideal Bullet Weight vs Twist, Shooters Log

Now for penetration, below is a picture of regular PMC Bronze .223 (an approximation to XM193) vs XM855.

PMC Bronze .223 vs XM855 Green Tip
PMC Bronze .223 vs XM855 Green Tip

The depth of penetration against the 3/4″ steel plate was .20 inches for the 55gr and .35 inches for the XM855.

The complete video is here, but get ready for a lot of misses (I’d start halfway in).  So I’d say it does penetrate more but it doesn’t cut through steel like butter.

And because it penetrates, it will do a good number on steel targets and potentially spark a fire, so many ranges do not allow it.

Last thing, is the price difference.  Most likely you’re going to see 193 slightly cheaper than 855 by a few cents.  Nothing too much of a deal breaker.

So to sum it all up:

  • Pricing is pretty similar
  • Some ranges do not allow steel core bullets such as the M855
  • M193 likes 1:9 barrels while M855 likes 1:8 or 1:7
  • M855 penetrates slightly better
  • M193 better performance against soft targets under 100 yards

And FYI, there was a brief scare in 2015 that the ATF was classifying M855 as armor piercing and taking it away from civilians, but they’ve since backed down.

Supplies dwindled as people thought it was going to be banned, but now it’s almost back to normal.

And our recommendation with the 855 thrown in there.  See our Best Ammo For Your AR-15 for more.

Best 5.56 XM855 (Green Tip)
at Palmetto State Armory

Prices accurate at time of writing

Prices accurate at time of writing

Got any questions? What do you shoot through your rifle? Let us know in the comments!

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21 Leave a Reply

  • Buddy

    Is it OK to use the XM855CSF 62 gr. in a 1:9 AR rifle ? It seems to work just fine out to 100 yards, and even out to 300 ... But do you think I should replace my 1:9 barrel with a 1:7 ? Will it make that big of a difference ?

    2 months ago
    • Fernando

      62gr green tips works fine with 1:9, 1:7 also pretty amazing. I have DD MK12 which is 1:7, I can got 0.5MOA in 100 meter.

      2 weeks ago
    • Just this guy, y'know?

      A "faster" twist (1:7 is faster than 1:9) stabilizes the longer 62 grain bullet in (X)M855 ammo better. This doesn't automatically mean you need a different barrel - it just means you shouldn't expect to shoot quite as accurately and consistently when you load up with (X)M855 as you might if you loaded with (X)M193 (and the shorter, 55 grain bullet used in it)

      1 month ago
  • Fred Sebastian

    IMHO: Your test would be more "visual" with thinner steel targets. I use 3/8" well casings as "Gongs". The M885s drills a clean hole, Ever'time. I would rather know what a particular "cartridge" WILL do not what it won't do. I already know it won't hurt a Jersey Barrier w/o a test.

    1 year ago
    • SkankHunt44

      And this one time, at band camp...…….none of us really give a flying fuck about you or how you think the test should've been run, numbnuts. Get a real life and stay the fuck off the internet, jagoff. Have a really nice day, scumbag.

      1 year ago
      • Donovan

        Take a shot of whiskey and STFU. The dude has a point. We all know M855 isn't penetrating almost inch solid thick steel. However thin steel that you typically find in plate armor.... Yeah might've been a better test. So chill out or better yet shut the fuck up if you don't have anything relevant to bring to the conversation other than opening your cum dumpster just to talk shit.

        7 months ago
      • AggregatVier

        Inspired as usual, Gerald.

        1 year ago
  • Hornet135

    PMC bronze .223 is not an approximation to XM193, it's really weak; about 500 fps slow.

    1 year ago
  • Jason

    I'm somewhat new to the AR scene, but I'm liking the M855 62gr ammo. I have a 10.5' AR pistol with a 1/7 twist, and have had no problems staying on target. I wouldn't recommend the M855's for soft targets, but if you want to punch through Cinder block, Stucco, or Drywall, these will do it

    1 year ago
  • Tony

    I worked at LCAAP for 5 years as an engineer making 5.56. There is generally no difference between XM193 and M193. Most of the XM193 ammo is made specifically for commercial pack and never tested against mil-spec, though it is made the same as the milspec ammo. Yes, if a lot fails the milspec for any slight variation it does gets sold as XM193 as long as it meets the commercial requirements. As mentioned in the article though milspec testing is very strict, and this ammo will work flawlessly for the average shooter. I use nothing but LCAAP ammo for all my plinking. Self defense or hunting I go with Hornady, who has recently partnered with Lake City to produce their Frontier line which I look forward to trying.

    2 years ago
    • Bob Lee Swagger

      Don't know if you or anyone else will read this...but that hornady frontier ammo is terrible!! We've had several ars blow up from that crap at the range I work at. Now granted I haven't seen it since our first shipment of it. But our other store had some guns blow up too from it. I haven't seen the issue in a few months so let's hope it's done with. But I still don't trust it now.

      1 year ago
  • Zee

    My boxes of XM193 literally say "military grade" on them, for even more confusion!

    2 years ago
    • Donovan

      Just like alot of product say American made then somewhere else in small letters..... Made in China lol

      7 months ago
  • Greg

    We been shooting here on the property for 27 years. All or m4s AR's came with 1-7 twist. Daughter shoots 55gr with a red dot site. She likes up the red dot with the standard ar front site, no carry handle in rear. The girl can almost always hit the eggs at 150 yards and it's pissing me off. Wife has a scope on her build on top of ar carry handle.. She has some trouble but seems to better with 62 gr. She is the sniper, also I struggle to keep her scope or carry handle from comming loose. 90 rounds I gotta check them. The last time I lock green locktite the hold downs and put them away for winter. Cranked them all. Now, my get up is standard M-16 SITES. Can't stand one more thing in the way or added weight. I have always been the quick shot,, and on target. I'd be the one taking those 300 meter shots and hitting the target almost alwYs... I don't know if it's the 1-7 twist, m4 colapsable stock, or my eyes as I am older now. I was part of the governors 20, meaning during a riot I would report to protect the gov with 19 others who were chosen too. I was a cook,lol and we were the only company that had the 50 cal on the roof, I could pull the trigger to almost always get one round only and on target. Since my mi,tray days have been over my most favorite rifle to hunt, plinking and target shooting became the chi ese sks standards, used, beat up wood stock, and just packed with kosmoleen. Everything I ever wanted to shoot,, dead nuts always, never missed without fi ding the reason why. If u e ever saw those things back before preban they were rough, Back to my issues. My point is, the sms has a similar short length stock, open SITES, and a wild round. Shoot it too fast it raises up and to the left,, I'm left handed so that don't happen to me much,, opposite should holding it. . On the ar 1-7 twist open m-16 SITES I have tried 55 gr 62gr 556 and 223. Shot with glasses and li,e always without glasses, supported and prone trying to figure this thing out. I have some 75gr this winter and that will be next. I can't get it, my groups are best with the 62gr. 556, but still 3 inch groups at 50 yards. Just isn't consistent I can't shoot an egg first shot, missed me off so I went inside grabbed the sms, standing unsupported shot the whole dozen before daughter reloaded her mag. That was last fall,, put my toys away till this spring.. got my eyes check, still only need cheaters to read. I'm lost. Oh I tried, federals and some some real armored rounds from the 90s , not a difference. Daughter shot the 62 gr in hers, 1/2" groups at 50 yards, but lower than with the 55gr. I tried hers,,, yeah I got nice groups, considering I shoot left to her red dot set up for right. Nice groups though, she shot mine, inconsistent. She agreed. My casing also shoot out at the 3 o'clock position sometimes 2 o'clock. Both girls shoot out around 4oclock is what I remember. But what would proper buffering have to do with single shots? Give some thoughts, and hope the readers do too.

    2 years ago
    • Dan

      When was the last time you "Defouled" the barrel, (i.e. removed all lead and copper)?

      1 year ago
    • Richard

      Read the specs for twist ratio vs bullet weight and you'll see. 1;7 works best with 62gr.

      1 year ago
  • William


    2 years ago
  • Norm Morris

    Good overview, thanks, but have to disagree on the twist rate comment. When I bought my first AR in 1994, 1:9 was it; there was no such thing as a faster twist, and those guns had no problem at all with M855/Ss109 "penetrator" ammo. To this day my 1:9 Bushmaster Dissipator shoots better with the 62 grain bullet than with the M193. When the M4 and 1:7 standard came along everyone assumed that was the best for all bullet weights, even 40 grainers, but the 1;9 is better for those light loads, and equally accurate and stabilizing as long as you stay under 70 grains. I don't go higher than 62. Fact is, most guys with a 1:7 won't go heavier than 62 either. My next upper for 3-gun will be a 1:8, which I think is the best compromise, and will finally allow me to start loading up some 77 grain loads.

    2 years ago
    • Eric Hung

      Hi Norm, thanks for the input. Yup, the best is to just try it out or go for a good middle of the road 1:8 twist. Let me know how that build comes out!

      2 years ago
  • Joe Smith

    I've contacted Federal. The difference in the M vs XM designation isn't that the XM failed anything. XM designated ammo was not submitted for military batch acceptance. Same ammo, no defects. Just to clarify.

    3 years ago
    • ehung

      Thanks for the clarification!

      3 years ago
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