I've finally nailed down some permanent (lol) AR setups and my secondary rifle is now a 16" recce-style with a SWFA 10X.

After zeroing at the range, finding a half a mag of random Hornady ammo and getting a .7" group out of it without even really trying, I've decided that it needs to be taken seriously.

I need to grab a few hundred rounds of appropriate ammo for it now. I have another setup for hunting, so this will be strictly for defensive/offensive use and maybe light competition along with occasional long range practice out to 800yds.

I'm in mostly flat plains with light hills, but something capable of accurately penetrating light brush would be handy.

Barrel is 1/7 twist.

In order of importance for this particular rifle:

1. Accuracy
2. Effectiveness

I'm not too worried about price but I don't want to spend $4 a round either.

It doesn't particularly like 62gr Fusion, but then again none of
my rifles have. M193 is about 2MOA in it. 855 was a little worse.

I've heard good things about Gold Dots but have only used them in handguns.

Suggestions?

I think many have decided that 77gr, of whatever flavor, tends to fit into what you’re wanting (decent all-around round) best.

Sierra seems to be king at making the bullet. Several companies load them.

IMI makes some good 77gr ammo. Federal, SIG, etc.

I've had great luck as far as accuracy with Sierra 308 bullets but haven't tried them in my ARs yet. Do SMKs tend to have decent terminal performance on par with dedicated defensive rounds?

My White Oak 18" SPR shoots Razor Core around an inch and PMC XTAC 77gr about .8 or so. Hand loads are better obviously.

A guys son said they were using the Barnes TSX in a military round and terminal performance was excellent. My kids have taken two bucks with the 70 gr bullet and they died where they were standing. Accuracy was phenomenal out of 18 inch barrel. Loaded ammo with it is not cheap but it is out there.

I use Black Hills  77gr OTM in my precision setups but I hear IMI Razor core is excellent as well.

Centurion Arms mk12 with NF ATACR in C1 mount and Surefire can.

Attached File

I’ve had good luck with the IMI 77gr. I also handload 77 Matchkings in an attempt to clone MK262 mod 1.

77gr tipped matchking is a substantial upgrade over the SMK. The latter bullet has a surprisingly high frag threshold of ~2200 fps. If you’re concerned about barrier performance, the Barnes 70gr TSX would be a better option even though it isn’t truly barrier blind. It can lose petals after going through auto glass, but at least it won’t underpenetrate. Bullets that are truly barrier blind, like the 62gr Gold Dot/Fusion you’ve tried, have rather low BCs and aren’t available in factory 5.56 loads. Maybe you could try reloading the 70gr Gold Dot.

The Tipped Match King is less likely to be accurate in any particular rifle, it’s ogive is less forgiving. The GMX looks promising but I’ve never tried it.

How bad is the dispersion with the 77gr TMK in your rifle? The substantially longer frag range and higher BC should make it more effective at distance even if the dispersion is a little wider.

The full pressure 5.56mm GMX factory loads have one of those distributor restrictions where they’ll only sell to cops, soldiers and a curious assortment of civilian jobs like EMTs and prison guards. If you can reload, the 70gr GMX could be worth a shot. It shouldn’t have the petal issue that the Barnes TSX exhibits.

IMI Razorcore 77gr comes to mind, as well as Hornady 75gr BTHP.  Black Hills makes a good 77gr load too,

The truth is, however, that the BEST way to reach the accuracy potential of this rifle is going to be hand loading.

FWIW:
I've had OUTSTANDING accuracy with the 77 TMK, in several uppers.  
But it is hard to find and more expensive than the SMK's.

I'm a green box guy so I cant recommend the 77's enough........ great consistant accuracy.

Otherwise:  FPNI.

Hornady 5.56mm 70 Grain GMX TAP Barrier






Hornady’s 5.56mm 70 grain GMX TAP Barrier load uses the same 70 grain GMX projectile that is available as a reloading component.  The 70 grain GMX is a monolithic hollow-point, but unlike similar monolithic bullets such as the all-copper Barnes TSX, the Hornady GMX is made from gilding metal (95% copper and 5% zinc).  Hence the “GM” portion of GMX.
 




 

The 70 grain GMX has a nominal length of approximately 1.048”, making it slightly longer than the 70 grain Barnes TSX.

 




 
The Hornady 5.56mm 70 grain GMX TAP Barrier cartridge is loaded in Hornady 5.56mm brass that has crimped and sealed primers.  The 70 grain GMX bullet does not have a cannelure per se, but the top relief band of the projectile functions as one, with the case mouth crimped into this relief band.  The cartridge also has case mouth sealant that fills this top relief band.  The load is charged with “ball” powder.





 

I chronographed the Hornady 5.56mm 70 grain GMX TAP Barrier ammunition from a semi-automatic AR-15 with a chrome-lined, NATO chambered 20” Colt M16A2 barrel.


 



 
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 has its onboard computer analyze the data to determine if there is any statistically significant difference between the two readings.  If there is, the chronograph “flags” the shot to let you know that the data is invalid.  There was no invalid data flagged during this testing.

The velocity stated below is the muzzle velocity as calculated from the instrumental velocity using Oehler’s Ballistic Explorer software program. The string 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:  73 degrees F
Humidity:  63%
Barometric pressure:  29.68 inches of Hg
Elevation:  950 feet above sea level


The muzzle velocity for the 10-shot string of the Hornady 70 grain GMX TAP Barrier  ammunition fired from the 20” Colt barrel was 2912 FPS with a standard deviation of 10 FPS and a coefficient of variation of 0.34%!

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 (and to give you an idea of how good the CV is for this factory loaded 70 grain GMX TAP Barrier ammunition) 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%.

 



 
….
 

I conducted an accuracy (technically, precision) evaluation of the Hornady 70 grain GMX TAP Barrier 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 used. 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 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 70 grain GMX ammunition, I fired a 10-shot control group using a hand-load topped with the Hornady 50 grain V-MAX.  That group had an extreme spread of 0.75”.

 





Next, three 10-shot groups of the Hornady 70 grain GMX TAP Barrier ammunition were fired in a row with the resulting extreme spreads:

1.34”
1.47”
1.16”

for a 10-shot group average extreme spread of 1.32”.  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 0.43”.
 

The smallest 10-shot group.




 
The 30-shot composite group.


 

…..

There is, only select unit can get it though. To your point, I’ve had excellent results with 70gr TSX on deer and hogs. It’s all I will use for hunting out of an AR. The TSX line leaves a bit to be desired in terms of BC, however, where I hunt with it it makes no difference. They do make a 77gr LRX which would obviously have higher BC but haven’t messed with it yet.

My best hand load for 5.56 chamber:

25.5gr Varget (near max and compressed)
2.250 COAL
Wolf SR primer
LC Brass

Should be around 2700fps out of a 16in but haven’t confirmed yet.

Frontier 75gr T2. The T2 bullet fragments down a relatively low speed.

If you plan on buying over-the-counter ammo I'd suggest Federal Gold Medal Match or Atlanta Arms 69s and 77s.  Another great option is Black Hills 73 Bergers.

If you have a good floated barrel, a decent trigger, a clear scope, and good form, 750-800 yards is fairly easy and do-able with a 16-inch carbine.  Hornady 75s start opening up groups with dispersion around 875 from an 18-inch barrel.

As for effectiveness, you have to hit it first.  No 5.56 / .223 is going to guarantee an instant kill at any range.

TBH I'd bit the bullet and get set up for reloading, even if just on a single stage press. For the cost of a case of "meh" ball ammo you can get all the equipment needed.  And then you can built quality ammo for 35c/rnd and up even at today's prices (bullet cost is where you'll pay...)

Even though I'm not commenting much, I'm still following this thread and paying attention. Some great info in here, thank y'all very much

Hornady's GMX bullets have been discontinued.  Their replacement CX Expanding has only 50 grain .224 caliber bullets for sale.  Nothing heavier for .224's...

BULLET BULLETIN: GOING FROM GOOD TO GREAT

Hornady CX Bullet Line

SMK were never designed for expansion or defensive use.  They are target bullets that have pressed into defensive use over the years.  
But, because they are the gold standard factory accuracy loaded ammo.
The govt was using them in M852 ammo, which was initially just meant for target use.  Then the Army changed their mind on it  here