The Sierra Tipped Match King line has made its way online, and it looks to add a new layer of awesome to shooting the AR15. Many shooters are aware of the previous level of awesome unleashed on the 5.56 ballistics world known as the 77 grain SMK which is famously put together in the Black Hills Mk262 Mod 1 loading. Finally… a projectile was produced that could really get the legs out of the 5.56 while still fitting in the magazine!
We all want better ballistics, and Sierra has introduced a more efficient design to both their prior 69 grain and 77 grain SMK offerings. The addition of a ballistic tip to the product line increases the ballistic coefficient of both the 69 and 77 grain loadings and reduces the velocity drop off and increases wind resistance. Below I highlighted the new tipped match kings and compared them to their old counterparts.
- STMK 69 grain BC: .375
- SMK 69 grain BC: .301
- STMK 77 grain BC: .420
- SMK 77 grain BC: .372
- XM193 55 grain BC: .255
As you can see, the new 69 grain loading has a higher BC than the old 77 grain loading, and the tipped 77 grain jumps to a BC of .420!
So how does this benefit you?
First and foremost, the wind resistance is strong with these new projectiles.While 55 grain stuff is the flattest shooting inside of 600 yards, it gets bullied by the wind.
90 degree wind at 10 mph @ 400 yards:
- 77 grain SMK @ 2750 FPS :15.9 inches drift
- 77 grain STMK @ 2750 FPS: 13.8 inches drift
- 69 STMK @ 2850 FPS: 14.9 inches drift
- 55 grain M193 @ 3250 FPS: 20.3 inches drift
At the edge of the 5.56s capabilities where we push to 900 yards, there is ten feet less drop from the tipped match kings vs the old match kings. I know what your saying: “Like that matters to me!” You’re right. Precious few of us have access to anything past 300 and those are the lucky ones. I can only shoot to 600 myself… How about a practical scenario?
Flight Flub Factor: When Velocity and BC Matter
In less pie in the sky fantasy, if we take the 77 STMK and shoot at a 9 inch round target at 450 yards, we have to estimate properly within 36 yards of error. We can mis-estimate that the target is 19 yards closer than it actually is, or 17 yards further out than it actually is and still get a hit from a center hold on target. The faster we push the bullet, and the higher the BC it has, the more forgiving the round is of our error.
Compare the above scenario with “normal” 77 grain SMK and the total flub factor is 33 yards where our mis-estimate can still score a hit. Drop the velocity to 2600-2650 FPS from a 14.5 inch carbine with the 77 SMK and you have 27 yards flub. Finally, a 10.5 inch SBR shooting 77 gr SMK with a velocity of 2500 FPS which yields an error window of 25 yards. So… choosing a longer barrel *is* a good thing!
25 yards seems generous, but best practice will be utilized when we choose the projectile with the highest BC available at the highest velocity we can afford to send it. 55 grain stuff is the flattest shooting “defensive” loading that we can get, and it would be a good choice in a world without wind. That said, going forward, I will be ordering 69 grain STMK for my future loadings. It shoots flat, and fights the wind better than what I currently shoot. Sierra looks to have a winner here, and hopefully we can examine some terminal performance gel tests soon.