The Sierra 168TMK out of a 24" barrel will be supersonic at 1000yd according to Etarget sensors.
Sierra .30 CALIBER/7.62MM 169 GR. HPBT MATCH
- Thread starter LVLAaron
- Start date
Ned Ludd
Silver $$ Contributor
The 168 TMK is a much different animal than the new 169 SMK. It's BC as listed by Sierra as being a bit better, but it is also a secant ogive bullet and may be a bit more finicky with regard to optimizing seating depth. The new 169 SMK is a tangent ogive bullet, like the 168 SMK, but with an improved boattail designed to minimize the dynamic instability issues long associated with the 168 SMK, while retaining the beneficial seating depth properties often associated with tangent ogive bullets.
Either the 169 SMK or 168 TMK would be much better choices for shooting out to 1000 yd. On more than one occasion, I've pulled 1000 yd targets for new F-TR shooters that tried to use the 168 SMKs, apparently without being aware of their boattail design issue. Typically, after numerous shots that hit the berm, sending large handfuls of twigs and pebbles into the pits, the shooter would actually manage to get a shot on paper that went through the target sideways, at which point they were asked to stop shooting. Nonetheless, although they wouldn't be my first choice for shooting at 1000 yd, pretty much any of the 168 gr designs offered by Sierra and various other manufacturers including Berger, Nosler, Hornady, etc., would be better choices than the 168 SMK for shooting out to 1000 yd, because none of the other designs have the steep boattail angle that creates the dynamic instability issues like the 168 SMK. In fairness, the 168 SMK was designed for 300 m competition, where the steep boattail isn't an issue, and it shoots fantastically well at shorter ranges.
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I shot those out of a 24 inch barrel. At 600 shot good in low wind, at 1000 I had few keyholes.
I think MidwayUSA has a computer generated clearance sale on items when they need to move x amount of stock. When that quota is met, prices go back to normal.
What was your muzzle velocity? I get 2750fps.
Shot them at 1000 out of my Palma rifle on Saturday. Load averages 2875 at the muzzle and was measured at 1373 by the shotmarker. Strelok puts it at .2627 G7.
That Palma rifle has something like a 30" barrel?
Is the powder you're using like H-4895?
32" barrel with Shooters World Precision
If I remember correctly it was about 2675 FPS. I didn’t really try to push them faster because I was getting very good accuracy at 600. When I shot 1000 I used the Sierra 175 Matchking. Strange thing was the 168 was better at 600 than the 175.
AckleymanII
Gold $$ Contributor
I have a 28" MHV Krieger 4 groove, and the 169 with a light touch on the lands shoots less than an inch at 300, wind flag and calm late evening wind, with 43.0-43.3g R#15, lapua brass, WLR, groups at 100 and 200 were tiny
.002 grip on the bullet was critical for the tune, annealed brass, FL body sized, then bushing sized..
The 169's will make you stand up and shout!
.002 grip on the bullet was critical for the tune, annealed brass, FL body sized, then bushing sized..
The 169's will make you stand up and shout!
2878 is mild and sweet
Last week I loaded up some 169 SMK's pushed by AR-Comp with various loads ranging from 40.1 to 41.3 grs to see which load performed best. 40.5 grs has worked very well for me with the 168's, so I figured their might be something that works well close to that sine this new Sierra bullet is only 1 gr more. The result was the 40.5 grs worked as well with the 169's as it die with the 168's. So. . . I loaded 50 more last night with this charge and seating depth intending to test seating depths to have a go at fine tuning these cartridge's. When I got to the range this morning, I found I had forgotten my little arbor press.
So much for those plans. I didn't have time to make the long trip back to pick the press up, so I decided just to shoot a few rounds. The result for this load is still pretty good and next time I might just take it out to some distance to see how well it's works then. I'm liking the bullet so far.
So much for those plans. I didn't have time to make the long trip back to pick the press up, so I decided just to shoot a few rounds. The result for this load is still pretty good and next time I might just take it out to some distance to see how well it's works then. I'm liking the bullet so far.
(I just made high master last week at 600yd. using them 1177-50X/1200)That my understanding of the 168gr smk . The boat tail length and angle are not best for longer range . The 168gr smk was designed specifically for 300yd match shooting so they did not care is it destabilized past 600 . I like the 168's and there's no reason to knock them cus they don't do well at longer ranges , they weren't designed to do that . As Ned Ludd points out don't use them if you plan to shoot past 600 .
So my guess is this new 169gr bullet has a different boat tail design and that is the biggest difference . Although until I get my hands on some and do a direct comparison who knows what all is different but I promise you the 1gr difference and closed tip is not the only difference . I bet the Ogive is longer and the boat tail is re designed as well
Yes, pretty much all redesigned. I've taken some measurements and compared the 168's to the 169's that have pretty much the same bearing surface (like at .554", as the BS's seem very close to the same anyway) to mitigate variances. The BTO's on the 169's are ~ .027" longer; the 169 boat tails are ~.028" longer and the 169's OAL's are ~.076" longer. Also, the base of the 169's is larger, but I had a hard time trying to get a good measurement; appearing to be .014" larger. I'm sure these number are not going to be the same as the official dimensions given variances we typically see in a lot, but I think it provides a pretty good perspective.
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Does anyone have a BC table (BC vs vel) for the 169s rather than just the single (.527) value given by Sierra?
I tested some loads at 1000 on Saturday and found that while I could hit the metal gong at 1000 and hit a specific patch of dirt on the berm, I couldn't get the shots to register on the ShotMarker system. (I was loading 43.6 gn of Precision Rifle in a Lapua Palma .308 case shooting from a 26" barrel.)
I tested some loads at 1000 on Saturday and found that while I could hit the metal gong at 1000 and hit a specific patch of dirt on the berm, I couldn't get the shots to register on the ShotMarker system. (I was loading 43.6 gn of Precision Rifle in a Lapua Palma .308 case shooting from a 26" barrel.)
what was your muzzle velocity?
According to my CED M2 chronograph, about 2650. I mistranscribed the load in my post, which was actually 44.6 gn of Precision. I backed off from 45 gns because primers were cratering. Vels were 2610 @ 44 gns and 2670 at 45 gns.
According to Shooting Lab, the vel should be 1307 @1000. Quick Target is giving me 1257.
One of my problems is that I only have 150 of these bullets left and no one has them in stock. If I use 50 experimenting, I'll only have enough left to shoot one match.
I'm thinking of trying a load using 748, which (of the powders in my inventory) seems to give the best velocity within pressure limits.
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