I’m thinking about consolidating my SD ammo stash to a single kind of round. I generally just practice and shoot with the cheapest 55-62gr fmj crap that I can get, so I have plenty of that.

But I have a handful of 62gr stuff (Fed Fusion and GDHP and TBBC/FBI3T)  and 77 grain stuff. I’m going to focus on shifting to just one kind for commonality across all my 5.56 ARs.  I don’t hunt (and wouldn’t) with any of my 556 rifles.  All of the ARs I’d grab for anything remotely serious have barrels 10.3”-16” in length and my actual HD bedside grab & go gun is a 10.3” ...

Consolidating to which round would serve me best?

I just go with IMI 77 OTM. Never tested it out of my 10.5, but from everything that I have read it is a viable projectile out of a shorter length 5.56 platform and the projectile has great expansion properties at lower velocities. Im sure theres tons of literature on the matter, so dont take my definitive word for it. I currently use spear 55 Gr SP in that 10.5 platform, primarily because I have an abundance at the moment and dont really believe in or see the reason to storing  non air tight sealed ammo long term.

I would say that having bulk of one as well as familiarizing yourself with the ammo’s capabilities in each platform is smart, therefore you have a solid uniformed understanding with the way it handles in an actual situation. As of now with crazy ammo prices I’ve just been buying whatever cheap brass I can find from reputable names in the industry for training ammo. Ill pay a few more CPR after reading some horror stories of some of the lesser known manufacturers selling remanufactured ammo that blows up in your barrel, where its likely the ammo manufacturer or your weapon manufacturer is going to even respond to your inquiries.

I prefer a BSP like the TBBC because if SHTF, odds are if I have to shoot someone I'll be in or around a car so barrier penetration is important

Yeah I've just started stocking the IMI 77gr myself.  Very accurate out of my builds, all of which have DD barrels (10.3, 14.5 and 16)

m855
mk262

And if you can find it it doesnt hurt to have some m855a1

Lots of good choices now.
It used to be simpler, and thank goodness, cheaper.
No matter what, make sure it will run, in your gun(s).

I went with 77gr imi, but whatever would probably work.

I would look at the frag or expansion range of the ammo I was considering relative to the velocities expected from that ammo thru the barrel lengths I would expect to be using it in. Something like FUSION 62gr MSR has a much longer max effective terminal performance range than 77gr OTM does from a 10.5" barrel, for example. 77gr TMK falls between the 2.

I have several hundred rds of 75 gr gold dot and otm but I’ve considered going to 62 gr gold dot because I don’t have to adjust my optics for the shift in different grain bullets.

My main bulk shtf stock up ammo is mk262.  Browntip for the plate carriers and HD rifle. A little m855A1 and RRPL. the rest is m193 for training.  I vote mk262. It's a known solid performer across a wide range of platforms and ranges. There is better stuff available but a lot more expensive.

Right before ukraine kicked off it was 92cpr with free shipping on midway. Only snagged a single case, 100% buying more next time it goes on sale. Last week I ran a 20 rd mag of it through my 14.5 Knights mod 2 @600 yards and was hitting steal with ease. Switched to norma 62 Grain m193 at the same distance and I was all over the place.

Do you live a rural environment.... or urban?

Rural - 77grn.
Urban - Fusion.

Because of its versatility... I'd go Fusion or whatever BSP you can get.

I love the 62gr fusion because the trajectory pretty closely matches m855

Bc is .301 and velocity is close

I would stock up on regular old M193, preferably IMI.

For the price that you’d pay to “stack it deep” on ammunition like TBBC, GDHP, MK262, etc. you could put away double, maybe triple of M193.

At one time I was only buying BH MK262 by the case load. Whenever it was available, I’d buy 1k at a time. Once the ammo crunches started to happen, replacing that particular ammo was almost impossible due to supply and cost. M193 on the other hand, though prices increased, I was still able to buy 1k every paycheck without hurting too much.

I have a mix of Mk262, M193 and M855, it's the best I could do.

I have different loads for different guns..
I stacked IMI 77g pretty deep.
I always have stacked 55g M193
Recently got a decent buy on black hills 62g TSX.
I always have m855 because that is what I practice with. Still have my stash from the "salad days"

I'm not an ammo expert though. I will refer you to Molon's posts. The dude is a walking ammo bible, assuming he walks.

Negative, 77 TMK has the longest range of fragmenting. In 5.56 pressure out of a 16-18" barrel it works out to 400 yards. As long as you cross 2700 fps you also cross 400 yard high level terminal capability.

Problem with Black Hills 77 5.56 TMK is they have been loading it shorter and shorter over the years and it gets harder and harder to find. Accuracy gets worse and worse while prices have gone up and up.

2700 FPS muzzle velocity with a G7 coefficient of .203 and a conservative 1600 FPS velocity threshold yields an expansion range of 570 yards.

While the fragmentation is reduced at this velocity, the expansion appears to be better at low velocities than the 62 gr Fusion - so if one counts a 1650 FPS Fusion as 'effective', a 77 gr TMK at 1650 FPS is better.

The TMK really is one of the best, if not the best .224" bullets out there. It does basically everything well, aside from barrier performance. Awesome bullet.

Black Hills 5.56mm 77 Grain Tipped MatchKing Ammunition






The Black Hills 5.56mm 77 grain Tipped MatchKing ammunition is loaded with the same Sierra 77 grain Tipped MatchKing projectile that is available as a reloading component (#7177), with the addition of a cannelure.  The Black Hills ammunition was actually brought to market before the reloading component was.





The 77 grain Tipped MatchKing is the longest bullet (that I’m aware of) that is currently being loaded by a major manufacturer to magazine length for the 5.56mm cartridge.





With a nominal length of 1.070”, the 77 grain Tipped MatchKing is 0.335” longer than a 55 grain FMJ bullet and 0.085” longer than the standard Sierra 77 grain MatchKing.





Not only is the bullet itself long, but the ogive section of the 77 grain Tipped MatchKing is also extremely long for a bullet loaded to magazine length in the 5.56mm cartridge; so much so, that the grooves of the cannelure extend into the ogive of the bullet, as evidenced by the “arrow head” shaped cannelure grooves.  














The Black Hills 77 grain Tipped MatchKing ammunition is loaded in 5.56mm WCC brass that has the annealing iris still visible.  The primer pockets are crimped and sealed.  The case-mouth is crimped but has no sealant.  The load is charged with “ball powder.”








Velocity


I chronographed the Black Hills 77 grain Tipped MatchKing ammunition from a semi-automatic AR-15 with a chrome-lined, NATO chambered 20” Colt M16A2 barrel with a 1:7” twist.





Chronographing was conducted using an Oehler 35-P chronograph with “proof screen” technology. The Oehler 35P chronograph is actually two chronographs in one package that takes two separate chronograph readings for each shot and then utilizes its onboard computer to analyze the data to determine if there is any statistically significant difference between the two readings. If there is a statistically significant difference in the readings, the chronograph “flags” the shot to let you know that the data is invalid. There was no invalid data flagged during this testing.

The velocities stated below are the muzzle velocities as calculated from the instrumental velocities using Oehler’s Ballistic Explorer software program. The strings of fire consisted of 10 rounds over the chronograph.










Each round was single-loaded and cycled into the chamber from a magazine fitted with a single-load follower. The bolt locked-back after each shot allowing the chamber to cool in between each shot. This technique was used to mitigate the possible influence of “chamber-soak” on velocity data. Each new shot was fired in a consistent manner after hitting the bolt release. Atmospheric conditions were monitored and recorded using a Kestrel 4000 Pocket Weather Tracker.






Atmospheric conditions

Temperature: 72 degrees F
Humidity: 44%
Barometric pressure: 29.64 inches of Hg
Elevation: 950 feet above sea level

The muzzle velocity for the 10-shot string of the Black Hills 77 grain Tipped MatchKing ammunition fired from the 20” Colt barrel was 2808 FPS with a standard deviation of 14 FPS and a coefficient of variation of 0.50%.

For those of you who might not be familiar with the coefficient of variation (CV), it is the standard deviation, divided by the mean (average) muzzle velocity and then multiplied by 100 and expressed as a percentage. It allows for the comparison of the uniformity of velocity between loads in different velocity spectrums; e.g. 77 grain loads running around 2,650 fps compared to 55 grain loads running around 3,250 fps.

For comparison, the mil-spec for M193 allows for a coefficient of variation of approximately 1.2%, while one of my best 77 grain OTM hand-loads, with a muzzle velocity of 2639 PFS and a standard deviation of 4 FPS, has a coefficient of variation of 0.15%.





Accuracy


I conducted an accuracy (technically, precision) evaluation of the Black Hills 77 grain Tipped MatchKing ammunition following my usual protocol. This accuracy evaluation used statistically significant shot-group sizes and every single shot in a fired group was included in the measurements. There was absolutely no use of any group-reduction techniques (e.g. fliers, target movement, Butterfly Shots).

The shooting set-up will be described in detail below. As many of the significant variables as was practicable were controlled for. Also, a control group was fired from the test-rifle used in the evaluation using match-grade, hand-loaded ammunition; in order to demonstrate the capability of the barrel. Pictures of shot-groups are posted for documentation.

All shooting was conducted from a concrete bench-rest from a distance of 100 yards (confirmed with a laser rangefinder.) The barrel used in the evaluation was free-floated. The free-float handguards of the rifle rested in a Sinclair Windage Benchrest, while the stock of the rifle rested in a Protektor bunny-ear rear bag. Sighting was accomplished via a Leupold VARI-X III set at 25x magnification and adjusted to be parallax-free at 100 yards. A mirage shade was attached to the top of the free-float hand-guard. Wind conditions on the shooting range were continuously monitored using a Wind Probe. The set-up was very similar to that pictured below.






The Wind Probe.




The test vehicle for this accuracy evaluation was one of my semi-automatic precision AR-15s with a 20” stainless-steel Lothar-Walther barrel. The barrel has a 223 Wylde chamber with a 1.8” twist. Prior to firing the  Black Hills 77 grain Tipped MatchKing, I fired a 10-shot control group using match-grade hand-loads topped with the Sierra 77 grain Tipped MatchKing (without a canelure). That group had an extreme spread of 0.68”.













the control group . . .





Three 10-shot groups of the Black Hills 77 grain Tipped MatchKings ammunition were fired in a row with the resulting extreme spreads:


1.26”
1.14”
1.37”


for a 10-shot group average extreme spread of 1.26”. The three 10-shot groups were over-layed on each other using RSI Shooting Lab to form a 30-shot composite group. The mean radius for the 30-shot composite group was 0.41”.



The smallest 10-shot group . . .





The 30-shot composite group . . .






MK262 Comparison

The table below compares the test results from this article to my previously obtained test data for Black Hills MK262 Mod 1 ammunition, which is loaded with the standard Sierra 77 grain MatchKing (with a cannelure.)







A.E.S = average extreme spread for three 10-shot groups at 100 yards

M.R. = mean radius for the 30-shot composite group

M.V. = muzzle velocity

S.D. = standard deviation of muzzle velocity

C.V. = coefficient of variation of muzzle velocity


…

Thank you DevL. I am, by no means, an expert and if there are errors or holes in my logic, I appreciate knowing about it.
I do not disagree with you at all out of a 16-18" barrel. Given that the OP specifically referenced his 10.3" SHTF/HD carbine, I was trying to point out that when looking for ammo, he should take into account the velocities from his barrel lengths and the intended use(s) of the rifle(s).

Below are the numbers I based my ammo choices on.
Much of the data came from this thread:
Suppressed SBR Ammo velocities.

My ammo choice of Fusion 62 gr was based upon my 10.5", 12.5" and 14" carbines.

My example from the post you quoted was for my 10.5" suppressed carbine.

From a 10.5":

IMI 77 OTM LR MOD 1 has a MV of about 2403fps. It's fragmentation velocity is around 2100fps fps. That puts the distance about 140 yds.
Black Hills 77 TMK has a MV of 2438fps. Its fragmentation velocity is about 1900 fps.                       That puts the distance about 300 yds.
Federal Fusion MSR 62 has a MV of about 2530fps. It's fragmentation velocity is about 1700 fps.       That puts the distance about 350 yds.

11.5":
77 OTM = ~180yds
77 TMK = ~300yds
62 MSR = ~380yds

12.5":
77 OTM = ~220yds
77 TMK = ~325yds
62 MSR = ~415yds

14.5":
77 OTM = ~235yds
77 TMK = ~380yds
62 MSR = ~425yds

77 TMK is a good choice, if you can find it. Maybe, at the Fusion MSR minimum frag velocity (1600fps), the TMK has better expansion, I don't recall seeing data on that nor were 500yd+ distance shots a prime concern so that was not factored into my choice. For MY SBRs and their optics and intended uses, both 62 MSR and TMK are good choices. If TMK was available and I had longer range optics, I would probably choose the 77 TMK over the MSR 62.

Video of the 77 gr TMK at 1650 FPS again.

1650 FPS TMK shot

There is also a member on this board who recorded an antelope kill at 1780 FPS with 77 gr TMK - bullet expanded with reduced fragmentation.

Expansion of 62 gr Fusion at 1650 FPS is very modest. I would not really put the comfortable threshold below that velocity; while the nose might still open up a little at slightly lower speeds, it will likely not result in a petal formation that is noticeably wider than the base of the bullet, therefore resulting in a very minimal increase in tissue destruction. Leid has a photo of a middle weight Gold Dot or Fusion shot into water at around 1650 FPS but unfortunately I can't find it.

i was able to get about 600 rounds of IMI 77gr for a "decent" price so that is what i have loaded in SHTF mags and all my 5.56 AR's are zeroed for it.

i put together a handload that is slightly more accurate but holds close to the POA POI of the IMI that i use for practice.

My general theory boils down to:

M193 for barrels >16"
Mk262 for barrels <16"

Though my friend runs only Mk262. His logic being just about any body armor on the market is going to stop 5.56 unless its velocity is really pumped up.

He's essentially correct, the only plates that M193 might be expected to penetrate are steel plates and *maybe* a very limited selection of special threat and level III plates, and full steel is not likely to be worn by anyone who is particularly dangerous. This capability only exists at close range and the likelihood will decrease with any kind of noticeable angle.

The overwhelming majority of ceramic level III and III+ plates can stop M193 moving at 20" barrel speeds and most likely considerably faster. Level IV is hard to penetrate even with extremely rare M995 tungsten core armor piercing ammunition. ESAPI Rev G onwards (mil standard issue) is explicitly rated for 3 hits of M995.

Keep in mind, all of these plates look pretty much the same in a carrier. You're not going to know which one you're shooting at unless you have prior knowledge.

Different loads for different rifles for me. Still evaluating some things but i've seemed to settle on IMI 77g razor core on my 20". My Socom gets 62g Black Hills TSX/M193. My 11.5 gets M193. IF SHTF, i'm taking my 20" and 14.5. So there is that.

I have been a MK262 user for years. I’m down to my last 1500 rounds and just can’t justify replacing it. I have switched everything over to IMI M193.

I will continue to use the M193 without second thoughts.