ss109/m855--m193--and77otm

[newguy]

could you please explain the differences and which applications each one is best for.


And is one an all around betterfor all purposes

[LTMattyL]

This question probably fits better into the Terminal Ballistics or ammuntion subforums. Maybe one of the mods can move it.

I think a good answer to your question can be found at the following link.

http://www.ar15.com/ammo/project/Self_Defense_Ammo_FAQ/#.223

My personal view is the following:

M855 and M193 - Training Use

77gr OTM - Long Distance/Accuracy

[NWcityguy2]

M855 is a full 5.56 pressure round and should be shot in rifles with at least 1:9 twist ans 5.56 chambers. It will also leave pits in steel targets though it is not true armor piercing ammunition. SS109 is simply the bullet itself an not the cartridge. It can be loaded to any safe pressure that the reloader prefers. Accuracy wise it is completely run-of-the-mill and terminally it is outclassed by commercial bullets in every way.

M193 in its original military loading is loaded to 223 pressures (55k psi vs 62,350 psi). It will sport a 55gr FMJBT and is once again run-of-the-mill accurate and terminally outclassed by commercial bullets.

I don't use 77gr OTM bullets but they are traditionally used by long range shooters.

When buying commercial ammo the only positive to using M193 is the price. For shooting paper and steel at 100 yards or less, or freehand, you are saving yourself money because the difference is negligible between them and a commercial HP/SP. Reloaders like them for the same reason plus the boat tail design makes it easier/faster to reload. I personally use Hornady 55gr SP W/C because they are generally the same price but offer a more accurate flat based bullet that will expand in living tissue.

When comparing strictly M855 to M193, buy the M193. There is nothing to be gained by shooting M855 and M193 won't chew up steel targets over time.

[Agnostic]

Count me as one who would primarily shoot the heavies if it wasn't cost prohibitive (dammit, I have got to start reloading!). The 69gr and 77gr SMKs are very accurate from my AR and do well in the wind. My barrel really seems to like the 69gr SMKs in particular. I also like the Hornady 75gr Match, although I tend to see better results with the SMKs.

For lighter bullets that are accurate, I have had good luck with 55gr V-max.

For 5.56 55gr FMJ, I like the PMC x-tac. It's cheap and I have had surprising accuracy with it out to ~400yards. It meets my plinking needs when accuracy isn't paramount.

I tend to stay away from xm855. The range I frequent doesn't like the bullets with the steel penetrator and the 55gr loads are cheaper for plinking.

I like the Barnes TSX for home defense. They may not be suitable for everyone due to the amount of penetration they show in gel tests and hogs, but they suit my situation well and the hog hunters have had really good luck with them. But, I did pick up a few boxes of 62gr fusion for kicks, we'll see how they do out of my barrel.

If I had to choose from M193, M855, and a 77gr OTM load, for my purposes, I would choose the 77gr OTM.

[Zane1844]

One thing to keep in mind, if it matters at all, a lot of scope BDC's (think ACOG) are set for the trajectory of M855. Again, ACOG's also are set for M193.

I use M193 for all range use.

I am, however, going to start using the MagTech (CBC) 62gr 5.56 FMJ. Even at the slightly higher price. It is the best.

[RyanB]

M193 is 5.56mm. It's more accurate than M855, though not terribly accurate.

[yhmspecter]

M855 is a full 5.56 pressure round and should be shot in rifles with at least 1:9 twist ans 5.56 chambers. It will also leave pits in steel targets though it is not true armor piercing ammunition. SS109 is simply the bullet itself an not the cartridge. It can be loaded to any safe pressure that the reloader prefers. Accuracy wise it is completely run-of-the-mill and terminally it is outclassed by commercial bullets in every way.

M193 in its original military loading is loaded to 223 pressures (55k psi vs 62,350 psi). It will sport a 55gr FMJBT and is once again run-of-the-mill accurate and terminally outclassed by commercial bullets.

I don't use 77gr OTM bullets but they are traditionally used by long range shooters.

When buying commercial ammo the only positive to using M193 is the price. For shooting paper and steel at 100 yards or less, or freehand, you are saving yourself money because the difference is negligible between them and a commercial HP/SP. Reloaders like them for the same reason plus the boat tail design makes it easier/faster to reload. I personally use Hornady 55gr SP W/C because they are generally the same price but offer a more accurate flat based bullet that will expand in living tissue.

When comparing strictly M855 to M193, buy the M193. There is nothing to be gained by shooting M855 and M193 won't chew up steel targets over time.

Not completely true in regards to m193, it is also loaded to 5.56mm pressures not .223.M193 is also pretty bad on steel compaired to m855 due to higher muzzle velocity. I have some AR 500 steel that is significantly pitted due to M193 inside of 100yrds..

[RyanB]

Also many ACOGs, perhaps most, are designed for M193.

[markm]

M193 is pretty much useless to me. Tears up steel. Not very accurate. Too hot and chews up brass. Poor long range, and mediocre short range performance.

I'll load SS109s for banging steel where missed aren't going to hurt my feelings.

77s are the answer in my opinion. And I'll load those bulk 75 gr PRVI bullets for blasting/practice when I don't want to burn up SMKs.

[aklaunch]

M855 are for when the zombies are behind thin barriers or glass
XM193 is for when they are out in the open inside of 2750 fps (not too much past 150 yards out of a carbine)
77 OTM is for when they are out in the open and work better towards the end of max range envelope.

My XM855's shoot about as accurate as my 7.62 Wolf ammo does out of the AK47. And... I can't take them to comps where steel plates are involved.

It is worth having a case of them for the apocalypse.

For everything else... About anything works better.

[tw4]

I shoot m855 and Mk318 both 62gr 5.56 I keep Mk262 (77gr 5.56) as kind of a go to because it has the same trajectory as the m855. the only time I shoot xm193 or .223 is for close range drills on paper.

[Keith E.]

I shoot m855 and Mk318 both 62gr 5.56 I keep Mk262 (77gr 5.56) as kind of a go to because it has the same trajectory as the m855.

tw4,

How far out are the trajectories the same?

Sorry OP but it may be helpful in making your decision.

Thanks,
Keith

[tw4]

- 300 yds.

I'm looking for a good graph -