Sierra's new 30 caliber 169 hpbt match king

[zeke]

Has anyone tried this new bullet in 308 yet ? Am wondering if it needs to be seated deeper in most rifles like the tmk's?

Thanks

[Jim Watson]

Never heard of it.
Does it have a better form factor than the good old 168 gr International?

[Bart B.]

Read all about it here.....

https://www.sierrabullets.com/produc...gr-hpbt-match/

[mikejonestkd]

Interesting, not sure what it can do that the 168 Tipped match king can't do though, the BC isn't any better @ .527 vs .535 for the TMK
Might have to try them out this year! nothing wrong with trying a new bullet!
Zeke, the 169 MK looks to be longer than the old classic 168 MK, so you'll have to seat it out farther or reduce your powder charge a bit.

[Unclenick]

The Tipped Match King line features secant ogives. This is a tangent ogive design. Tangent ogives seem to be less fussy about bullet alignment (they tend to self-correct in the throat more) and less picky about seating depth, so it should be easier for folks to make them shoot tight groups. The secant ogives have higher BC's. In this instance, though, the boattail of the tangent ogive design has been lengthened to narrow the diameter of the flat part of the base. That diameter also affects BC, with smaller being better.

[TXAZ]

What's the chance Federal, et al, will have this in a factory round?
(I realize this is the handloading forum but don't reload)

[zeke]

While only have access to a 600 yd range, the 168 TMK carry's noticeably better than the 168 HPBT in terms of drop/drift. But that is in a rifle that can seat them out far enough to not loose any powder space, if that even matters.

[Unclenick]

I wouldn't be surprised if a factory round showed up. I notice they claim to have closed the nose so it looks like an FMJ rather than a MatchKing. That would eliminate the need for uniforming and tipping dies. I also measured the boattail angle and came up with 10°, instead of the 13° angle used on the original 168 and which is known to have some stability issues in the transonic range when fired from a 10" twist barrel. The base of the bullet in the photo is slightly rounded by barrel distortion from the camera lens, so I wouldn't be surprised if it turns out to actually be a 9° boattail without the distortion. That's what is used on the 175-grain SMK and on the old 173-grain military M1 Ball and M1 Type match bullets.

[old roper]

Here some more information

https://forum.accurateshooter.com/th...match.4026940/

[Bart B.]

Unclenick, the original 168's in M852 match ammo stayed supersonic through 1000 yards shot from 7.62 NATO Garands with 24" 1:12 twist match barrels. That's my experience .

[std7mag]

BartB,

Wouldn't the Garand be chambered in 30-06, as opposed to 308 (7.62X51)?
This would possibly give upwards of 200 fps additional muzzle velocity, making for a longer distance before hitting the transonic range.

The new bullet given better form specifically targeting the velocities given by the 308 cartridge.

I'm guessing it would only work that much better in the 30-06 cartridge.

[Road_Clam]

The 168's are well known for incurring instability in certain circumstances pushing beyond 800 yds . When I attended the Sig Saur "Reach for a Thousand" instructional class there was a shooter using a Rem ACCSD in .308 with a 20" bbl, and he shot excellent out to 700 yds, but when we were at 1000 yds he was getting inconsistent hits on the 48" steel gong , he was using the Sig supplied FGMM 168 SMK gr ammo . The instructor commented that they were out of the preferred FGMM 175 SMK ammo and that they do see instability with certain rifles as you are right at the transonic threshold at 1000 yds in certain rifle configurations and weather conditions with the 168 gr ammo. The day we shot is was cold and very damp which slows bullet velocities even more. I shoot the 168 SMK's in 308 frequently at 600 yds and never had issues. Looking foward to trying the new 169's . I have a R700 26" bbl Varmint and thus far my go-to bullet is the 168 SMK .

[Jim Watson]

When I was shooting F class, there was a guy who amazed me by getting good accuracy at 1000 yards with 168 gr .308s. Until he ran out of bullets and bought new 168 SMKs and it all went to pot.

[old roper]

Bart, Isn't NRA 1000yds shot slow fire?

[Bart B.]

Originally Posted by std7mag

BartB,

Wouldn't the Garand be chambered in 30-06, as opposed to 308 (7.62X51)?
This would possibly give upwards of 200 fps additional muzzle velocity, .

It is a USN 7.62 conversion. And only about 50 fps faster than M14 rifles.

[Bart B.]

Originally Posted by old roper

Bart, Isn't NRA 1000yds shot slow fire?

Yes.

[Shadow9mm]

Its a pretty interesting projectile..... I may have to snap up a few of these. thanks for the heads up.

[Unclenick]

Originally Posted by Bart B.

Unclenick, the original 168's in M852 match ammo stayed supersonic through 1000 yards shot from 7.62 NATO Garands with 24" 1:12 twist match barrels. That's my experience .

The instability in the 168 from a 10" twist happens at about 1400 fps; top end of the transonic range. One year I took Mid Tompkins old Long Range Firing School, and the first shooting was 800-yard targets and lots of folks were shooting 168s from 10" twist guns. There were all sorts of moans and groans up and down the line as nobody with them (myself included) could stay on paper and the pits reported keyholing where they did hit. Kevin Thomas, who still worked for Sierra at the time, was also at the school and he simply commented that the 168 was designed as a 300 meter Internation Rifle bullet and the fact it shot well to 600 was a bonus for the company. Bryan Litz later explained in one of his books that the bullet design has a dynamic instability. That means that under some conditions, presumable one of being over-stabilized, it will overshoot when attempting to correct into the wind. Since the Magnus moment of the bullet is usually involved in these events and is behind the center of gravity, the thinking is the 13° boattail angle, which settles the bullet fast at shorter ranges, is part of the problem at longer ranges at faster spin rates.

Anyway, the LRFS, during the lunch break, all of us with 168's and 10" twist barrels ran to commercial row and bought ammo loaded with the 175-grains MatchKings (9° boattail) which were known to do well out at distance, and when we returned we all parked nicely on paper and stayed there and the keyholes were gone.

[Bart B.]

I was at 6600 feet elevation at the NRA Whittington center.

[Unclenick]

That thin air or the 12" twist or both may be responsible. It would take some persistent fiddling with a 6 DOF exterior ballistics program to sort the exact cause out.

[USSR]

I spotted once for a guy who tried using Sierra 168 HPBT's in 1,000 yard F Class. It was ugly.

Don

[Unclenick]

In the 10" twist guns we had a Perry, the tumbling bullets never would have made it 1000 yards. I know folks with 12" and 13" twist barrels have hit at 1000. but not always. The LRFS was actually the second time I've seen 168's tumble. The first was at a Gunsite Precision Rifle class. We had all purchased ahead some PMC match ammo offered as an option for the class to buy to avoid shipping ammo ahead and that was loaded with the 168. One of the targets was a 748-yard steel "popper" across a valley from us. The wind through the valley was an essentially constant 20 mph, and nobody could hit the popper, even with 12" twist guns. Bullet impact dust clearly showed them hooking left then right then diagonally and never repeating the previous POI. And the valley ridge we were firing from would have been at nearly 5,000 feet. So, enough wind, and the instability seems to appear starting right around the 700-yard point. My rifle and a number of the others had 24" barrels.

[Bart B.]

Regarding thin air at altitude and shooting at 1000 yards, 308's need 4 to 5 MOA more sight elevation going from 6600 feet above sea level to 600 feet where the thicker air slows bullet velocity.