Home Forums Hunting & Shooting AR and Tactical Rifles New Tipped 77 grain SMK with a B/C .420

From Accurate shooter link:
_______________________________


There will be six (6) new TMK bullets, two in .224 caliber, and four in .308 caliber. The six new tipped bullet types should be available in �early 2015″. Sorry, Sierra will not be offering 6mm, 6.5mm, or 7mm TMKs for the time being, although Sierra will introduce more TMK varieties in the future. Currently, Sierra is focusing on �the most popular calibers�. Notably, the new 22-Cal 77gr TMK has a 0.420 BC � identical to the BC of Sierra�s 80gr non-tipped HPBT MatchKing. So, you get the BC of a heavier bullet in a lighter projectile that can be pushed faster. That�s big news for .223 Rem and 22-250 shooters.



Bullet Name (Click for ballistic coefficients)

Brand

Item

BC (G1)





.224 dia. 69 gr. Tipped MatchKing (TMK)

Tipped MatchKing

7169

.375 @ 2700+ fps





.224 dia. 77 gr. Tipped MatchKing (TMK)

Tipped MatchKing

7177

.420 @ 2400+ fps

__________________________

I am wondering if the 77grainers will fit in magazines and feed nice.

3 grains lighter than an 80. I doubt it will be significantly faster.

Seems like kind of a bone head move. Why not a tipped 80 with an even better BC? If you want mag fed, why not a different weight to avoid confusion?

The 69 looks like it will save nearly 1/2 MOA of wind at 300yds, but still not equal to the 77 SMK. (According to JBM)

the other thing is with a tipped bullet don't you get a longer bullet albeit slightly. especially in 223 that means you run up against the magazine quicker.

Negative. They were designed for a reason. The 77gr TMK is the highest BC bullet that can be loaded to standard M4 mag constraints. They also offer dramatically increased terminal performance over existing lines. The need has been there and this will become THE bullet.

Anything other than the plastic tip that is different than the regular 77smk?

If Hornady had made their's to fit magazine lengh... what were they thinking at the time???

As someone who shoots ammo from a magazine, I am excited to see this bullet. Glad Sierra brought it out. Now maybe a .308 cal 175??????

The ogive is different and slightly different manufacturing. The 77gr SMK has always had good terminal performance... When it worked. The problem is like all SMK's they suffer from variability. The TMK solves that.


Are you talking the 75gr AMAX from Hornady? If so that wasn't built for or designed for AR's. At least not for magazine feeding. Remember they were designed for matches.


CBMJR,

Sierra has designed a 69gr and 77gr .224 TMK, a 125, 155, 168 and 175gr .308 cal TMK's.

Awesome, thanks. Didn't know about the .30 cals.

Will the new 77TMK run well in a 9 twist?

No problem.







Highly doubt it. That's why they designed the 69gr version.

that is if your trying to carry 10#'s in a 5# sack. anytime you put a bullet that size in the 223 your going to limit the power the case can hold.

your not going to be able to compare this bullet to the 77 hollowpoint. This bullet is going to have a much larger hole in the front for expansion because it holds the plastic tip. It may or may not work well at certain ranges.

I think with powders like Varget that may be true. Powders like Ramshot TAC or similar sized grain powders still leave plenty of room to get the longer bullets up to speed. I don't know how these will perform because I haven't shot any but on paper, they look good. Better than the SMK's so far.

I'm not understanding what you are trying to say? Are you trying to say that a 77gr mag length bullet is bad?

And what are you trying to say with- "it may or may not work well at certain ranges"?

I can fit 25 gr of Varget behind a regular 77. Doubt these will be more than 1/2gr different. Unless you are running moly or have a worn bore, 25gr Varget is too much.

powder capacity is a no brainer. simply use one of the slowest powders that you can fit a full charge into the space you have available.

if the 'may or may not work well at certain ranges' is speaking of terminal effects, it would be hard to do worse than the SMK. my thoughts are the tip would enable Sierra to make expansion more consistent. Sierra's product description mentions having a thicker jacket than their varmint bullets.

and, Sierra says these will need 1:7" or 1:8" twist.

I took the "it may or may not work well at certain ranges" comment as a question of the bullets stability by having a larger hole in the front for the plastic tip. Until we get to cut one open and compare to other bullets, I don't see why it would work any worse than an AMAX or other tipped match bullet. I've ahot lots of AMAX bullets into paper and steel at 1000 yards and never had issues with stability even when the bullets went transonic.

I'm liking this news..

It is a superb bullet designed specifically to address the fleet yaw variability of the 77gr SMK loaded in MK262. The terminal performance is virtually ideal for an open air bullet in soft tissue. It upsets well below 2,000 fps. The BH 5.56 load is averaging between 2,600 and 2,650 from 14.5in barrels. It is a mag fed round that provides adequate terminal performance to nearly 600 yards from 14.5 and 16in barrels.



Unsure what the questions are with regards to "stability", other than it will not stabilize in a 1/9 twist.

Sounds like the best carbine bullet yet, regarding effective range and terminal ballistics.

Remember that just cause its lighter doesn't mean you can push it faster... bearing surface has some effect on that plus case capacity in the 2.250 OAL setup....

Nothing is ever as simple as it seems.