168gr Matchking problem?????

[Smurfwarrior]

"Magpul Dynamics does not recommend students to utilize the Sierra 168 Grain HPBT Matchking projectile for the Precision Rifle 1 or 2 courses. This projectile experiences dynamic instability at extended ranges and does not produce consistent results at transonic flight speed and below."

Saw that post on a Magpul course offered in the training section. Anyone has more info?

 

[Killer Spade 13]

Re: 168gr Matchking problem?????

Not much of a problem. Known ballistics . . .

 

[Mile High Shooting]

Re: 168gr Matchking problem?????

The 168gr SMK out of a .308 is usually considered a 7-800yd bullet tops due to the instability during transonic and then subsonic speeds. There have been shots made longer but overall reliability for making longer distance hits goes way down after that 7-800yd range when compared to other available bullets.

For pushing further distances with a normal .308 you'll want at least the 175gr SMK or 168gr AMAX. Environmental factors, elevation, rifle barrel/velocity and other factors can make the 168gr SMKs get further but you'll usually see better results with the higher BC bullets.

 

[frankythefly]

Re: 168gr Matchking problem?????

I was also told this by a buddy of mine and also has to do a lot with elevation. Same goes with the 168 amax. I was shooting with a guy who was shooting 4 inch groups at 800yds with the 168 amax, but couldn't shoot anything past that. I however have found that the new Berger 168 hybrids do not have this issue and work well out to 1000yds.

 

[Smurfwarrior]

Re: 168gr Matchking problem?????

Very cool, thanks

 

[okiefired]

Re: 168gr Matchking problem?????

Yeah, I think there are a "few" people on this forum who have tried for years to tell others 168's aren't THE bullet of choice in a .308. 175/178's will equal or out perform them at every distance to 1k in my experience....and I havn't even tried the heavies.

okie

 

[bburnham]

Re: 168gr Matchking problem?????

Brian Litz explains this in his book. The instability issue with 168 SMK's is not a bc issue. The instability at trans sonic passage is caused by the particular shape of the boat tail. Other 168 bullets do not have this problem.

 

[okiefired]

Re: 168gr Matchking problem?????

Well, the best way to not worry about "tran sonic passage" at distance is to stay away from 168's and shoot longer, heavier bullets. Boat tail my ass.....there's a lot of 175+'s, no matter what the profile that will stay super sonic to 1K+ out of a 308. You certainly cant say that about a 168 and I just cant understand why anyone bothers with them.

okie

 

[sandwarrior]

Re: 168gr Matchking problem?????

We also need to talk about twist helping to alleviate the issues with the 168 SMK at 1k. 1-10" twisted .308's tend to put 168's into a more accurate group than do 1-11" or 1-12". The bullet itself will stabilize in a 1-13.5" twist. So, tightening up the twist helps the bullet during the disruption.
I have found this with other calibers, and what I've fired of the 168's (altitude and twist were always on my side) it helps considerably.

 

[Ring]

Re: 168gr Matchking problem?????

i watched 168's keyhole at 875y

 

[UIUCPPQ]

Re: 168gr Matchking problem?????

Informative video up there by John at 8541, ignorant question for you:

You said you did qualifications with 168gr which I don't doubt to be true; I had it in my head that the military used 175 in their .308 rounds. My question is am I just totally off base or is there a little knowledge you can drop on me to guide me in the right direction?

 

[kraigWY]

Re: 168gr Matchking problem?????

We High Power shooters found this out years ago (it was known before I really got into it in mid 70s.

The 168 SMKs work great across the course, 200,300 & 600 but wouldn't shoot for crap at 1000 out of M14/M1As. Often they would key hole.

They didn't have 175s back then but we had 180 SMKs, (not the same 180s they have now). They worked.

When we started getting M852s, we Mexican Matched them with the 180s for 1000 yard service rifle matches.

Its not a new problem.

 

[pjparker]

Re: 168gr Matchking problem?????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: kraigWY</div><div class="ubbcode-body">Its not a new problem. </div></div>

It has long been known that "friends don't let friends shoot 168 SMK's at 1000".

Even so, I have attempted it, thinking a 34" Krieger would push 'em fast enough to work OK. I seem to remember that I scored fairly well, but my scorer saved the 3" shot spotter that had distinctly oblong-looking bullet holes in it, so that's busted, too.

Paul

 

[AMTeam4]

Re: 168gr Matchking problem?????

168's will get the job done at 1000 yards but you'll get random flyers. The flyers make it difficult to differentiate between shooter err or the bullet being pushed beyond its limits.

I qualled the known distance portion of Scout Sniper School with 168's. We primarily shot 175gr but on occasion an old ammo crate of 168's would be delivered. There is a noticeable difference between the two bullets past 800yds.

At closer in distances the 168 is a great bullet. In my particular rifle the 168gr groups better at 100yds than 175gr so I will shoot the 168gr when doing dot drills.

If going to a LR course I would definitely take the 175gr rounds. With a good rifle/shooter/spotter combo you’ll be able to reach out past 1250yds.

 

[Jhnmdahl]

Re: 168gr Matchking problem?????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steeldinger</div><div class="ubbcode-body">Brian Litz explains this in his book. The instability issue with 168 SMK's is not a bc issue. The instability at trans sonic passage is caused by the particular shape of the boat tail. Other 168 bullets do not have this problem. </div></div>

This is exactly right. The angle on the boat tail is too steep, which isn't really a problem until the bullet starts to go subsonic around 800-1000 yards or so. So, if you shoot at a 600 yard range there's little to worry about, but they aren't a good choice for 800+ yards.

 

[okiefired]

Re: 168gr Matchking problem?????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jhnmdahl</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: steeldinger</div><div class="ubbcode-body">Brian Litz explains this in his book. The instability issue with 168 SMK's is not a bc issue. The instability at trans sonic passage is caused by the particular shape of the boat tail. Other 168 bullets do not have this problem. </div></div>

This is exactly right. The angle on the boat tail is too steep, which isn't really a problem until the bullet starts to go subsonic around 800-1000 yards or so. So, if you shoot at a 600 yard range there's little to worry about, but they aren't a good choice for 800+ yards. </div></div>

I just dont get this. Who cares about what makes them become unstable and when it happens? Find a load useing 175/178's (or heavier). They'll work as good if not better to 600 and after that they will simply walk off and leave the 168's. Even with a 12 twist barrel, there is nothing a 168 will do better than a 175/178 out of a .308 at any distance. If its not a "I get them really cheap" type thing, I just cant understand why anyone will waste the time with them.

okie

 

[Killer Spade 13]

Re: 168gr Matchking problem?????

I get them really cheap and they're much, much more available!

 

[slayer 2c]

Re: 168gr Matchking problem?????

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Killer Spade 13</div><div class="ubbcode-body">I get them really cheap and they're much, much more available! </div></div>

+1 my local gun store sells the 168 FGMM for 25.95 and the175's for 42.95. Since reloading isn't in the cards yet, I'll shoot the 168's. Hell my longest local range only reaches 550m anyways.

 

[Killer Spade 13]

Re: 168gr Matchking problem?????

Given I'm shooting a 26" barrel and the DA is always just about 1200 ft., I'll get a little bit better performance.