Black Hills Ammunition released an improved version of their famous 77 grain long range precision 5.56mm round. The new version features a green color polymer ballistic tip Sierra boat-tail projectile calls the Tipped MatchKing (TMK). It’s the first ballistic tip bullet by Sierra bullet. Besides of the original Mk262 77 gr military load, Black Hills has been a long time user of the Sierra bullets in their ammo in various calibers.
So what’s the difference between the new Black Hills 77 gr TMK comparing to original Mk262/77 gr SMK? The huge deal is that BC (Ballistic Coefficient) has jumped from 0.373 of to a whopping 0.420 with the new Sierra Tipped MatchKing projectile. While the original Mk262/77gr SMK’s BC is very close to that of the 147-150 gr 7.62x51mm’s ballistic performance, the new polymer tip bullet of Black Hills 77 gr TMK gives it the long range performance near the heavier 168 gr .308 caliber bullet.
Black Hills’ three 77 grain (5 g) 5.56mm ammo. The Mk262 military load on the left. The 77gr SMK (Sierra MatchKing) in the middle is basically the commercial production of the Mk262. On the right is the new 77gr TMK with its green polymer ballistic tip.
All three 77gr Black Hills long range precision loads gave me the identical 100 yards accuracy of average 0.5-0.7 inch groups out of both of my testing rifles with 18-inch barrel. With my heavy barrel 16-in Canadian C8 SFW clone, the average accuracy is 1.36 inch at 100 yards. The C8 carbine has an ALG Defense milspec trigger and the ELCAN Specter OS 4x prism sight. It’s 1 MOA or better with my 3-gun style AR-15 built with the lightweight Rainier Arms 18-in polygonal rifling barrel and Geissele Super 3 Gun trigger.
Black Hills 77 gr TMK Muzzle Velocity:
14.5 inch barrel: 2589.4 FPS avg.
(Daniel Defense and BCM lightweight hammer forged chrome lined, carbine & mid-length gas system)
16 inch barrel: 2683.1 FPS avg.
(BCM C8 SFW heavy profile chrome lined barrel w/ Simon steel sleeve, carbine-length gas system)
18 inch barrel: 2687.5 FPS avg.
(Rainier Arms Select Medcon stainless polygonal rifling, mid-length gas system)
18 inch barrel: 2712.5 FPS avg.
(BCM Mk12 SPR heavy profile stainless steel, rifle-length gas system):
My main testing rifle that I have used for testing the Black Hills 77 gr TMK. The upper is a Bravo Company Mk12 Mod 1 SPR with the KAC RAS free-float handguard and a Krieger stainless heavy barrel with 1-in-8 twist rate. The lower that I used has a Geissele SSA 2-stage trigger, a Magpul MOE+ pistol grip and a Vltor A5 EMOD collapsible stock. The support is provided by a Bobro Type 3 bipod and a Savvy Sniper precision rifle sling.
My secondary testing rifle has a Bravo Company Mk12 Mod 0 SPR upper with the PRI carbon fiber free-float handguard. It uses the same Krieger stainless steel heavy barrel but with the bare stainless finish. It actually has the lower receiver in the picture with a Iron Ridge Arms G2 single-stage combat trigger, the BCM Gunfighter pistol grip and B5 Systems’ Enhanced SOPMOD collapsible stock. The bipod that goes with the M12 Mod 0 is the Atlas V8 bipod and a Magpul MS4 Dual Quad Gen 2 sling.
The optics that I used with both rifles are the Leupold Mk4 2.5-8x36mm, the current DMR scope of the US Marine Corps, and the Hi-Lux Leatherwood M40 3-9x40mm, which is a new reproduction of the Redfield scope used by the USMC for the DMR/sniper rifle role during the Vietnam War.
Why is that both of my testing rifles are the Mk12 SPR clones? Well, the Black Hills 77 gr round was originally specifically developed for the Mk12 SPRs in service with the US military.
One of the benefit of the 77 gr Sierra OTM bullet used in the Mk262/77 gr SMK is that it lowered the fragmentation velocity. Therefore, it extended the terminal ballistic effectiveness of the 5.56mm caliber to a longer range. It’s a known fact that when firing standard 62 gr M855/SS109 round from the 14.5-in barrel of the M4 carbine, the fragmentation range is typically about 70-80 meters. Some of the US military units that have access to the Mk262 ammo are often using it in their M4 carbines to increase the fragmentation range to at least double that of the M855.
Ballistic gel tests of the new Black Hills 77 gr TMK fired from the 14.5-in carbine barrel length shows that it starts the gel expansion and fragmentation at less than half of the penetration depth as the Mk262 fired from the longer 16-in barrel. According to Black Hills, the 77 gr TMK round will reliably fragments at 1900 fps velocity. Comparing that to the 2700 fps needed for the 62 gr M855 and the older but more popular 55 gr M193. Which translating to if you use the Black Hills 77 gr TMK with your M4 Carbine style 14.5-inch barrel on your weapon, the effective fragmentation range will be at least triple.
I shot the Black Hills 77 gr TMK round out to 1000 yards on steel torso size target. Up to about 600 yards, there’s no noticeable difference between it and the Mk262/77 gr SMK. FYI, the Mk262 and the Mk12 SPR combination was developed by the US military for use as a small unit DMR with an effective combat range of 700 meters and 1 MOA accuracy.
Once passed 600 yards, I began to noticed the Black Hills 77 gr TMK is flatter shooting than the Mk262/77 gr SMK. At 1000 yards, the Mk262/ 77 gr SMK impacts almost a hashmark lower than the Black Hills 77 gr TMK when viewing through the Hi-Lux Leatherwood M40’s reticle. By using the Applied Ballistic App (courtesy of Sig Optics Media Event) on my smart phone, the Mk262 drops 51 inches lower than the Black Hills 77 gr TMK at 1000 yards, which was exactly what I was getting. My shots with the Mk262 was impacting at the foot of the target stand.
For the fun of it, I tried the Russian made Tula 75 gr steel case and Serbian made Prvi Partizan (PPU) 75 gr brass case 5.56mm rounds at 1000 yards with my Mk12 SPR. Both of those are being marketed as economical long range 5.56mm rounds. Discounting the accuracy, neither weren’t remotely close to the Black Hills, the PPU 75 gr landed far shorter at just pasting the 2nd hashmark in the M40’s reticle. The steel case Tula 75 gr was even worst with rounds impacting almost to the 3rd hashmark. Noted that the 3rd hashmark in the M40 reticle has twice the distance to the crosshair center as both the 1st and 2nd hashmark combined. It was very obviously that both have lower velocity and much lower BC than the Black Hills. Comparing to the sub-MOA accurate Black Hills, the PPU is at best a 2 MOA ammo and the Tula steel case is probably a 3-4 MOA round.
The new Black Hills 77 grain TMK is expensive but it is both a great long range precision 5.56mm round and a highly effective ammo to use with a short barrel rifle due to its significantly lower fragmentation velocity.