RifleShooter.com Reviews New .30-Cal 175gr Tipped MatchKings
We know our readers are curious about the new Tipped MatchKings (TMKs) introduced by Sierra Bullets this year. Our friend Bill at Rifleshooter.com got hold of some of the .30-Cal 175-grain TMKs and tested them in his .308 Win rifle. He found the bullets were very consistent in weight. As for bearing surface, the SD was fairly low (.002″), but measurements varied from 0.400″ to 0.407″. Seven-thousandths extreme spread is more than we like to see, as it may affect accuracy. Therefore we recommend you sort by bearing surface length before loading these in match rounds.
READ Full Sierra 175gr TMK Bullet REVIEW in Rifleshooter.com »
The new 175gr TMKs have a better BC* than the older-design 175gr BTHP MatchKings. The improved BC is a combination of a different shape and the plastic tip. Unfortunately, that tip increases the bullet’s overall length. Rifleshooter.com notes that this may be a factor those who are already loading SMKs to max mag length. With the new, longer TMKs you’ll need to put more bullet shank in the cartridge to maintain the same Cartridge OAL.
Bill explains: “The 175 TMK has an overall length of 1.380″, compared to 1.239″ of the SMK. The additional .141″ in length effects the OAL of the complete cartridge. In my .308 Winchester rifle, chambered with a Manson .308 Match reamer, the 175 TMK measured 2.950″ to the lands with the TMK, .070″ longer than 2.880″ capacity of a AICS magazine. While this isn’t a big deal for a shooter single loading his rifle, such as in F-Class … it is problematic with guns using a detachable magazine system.”
Measured weights of the Sierra 175gr TMK bullets were very consistent.
Bill tested for accuracy, but found the results somewhat disappointing, both with mag-length and single-shot-length loads. He believes more load development was in order. Keep in mind that Bill was NOT testing with a benchrest-grade rifle. On the plus side, Bill was pleased that he picked up some speed with the TMK: “Velocities were approximately 50 FPS faster than the 175 SMK with the same powder charge. This matches some reports I have read about the TMK being slightly faster than the SMK. However, my 175 SMK data was gathered during the winter when temperature were significantly cooler, I would not predict higher velocities with certainty.”
*Sierra advertises a G1 ballistic coefficient (BC) of .545 for speeds over 2400 FPS. This is an improvement over the 175 SMK, with an advertised G1 BC of .486 between 1800 and 2800 FPS and .505 over 2800 FPS. Bryan Litz of Applied Ballistics tested the 175 TMK and recorded a G7 BC of .267. That’s nearly 10% higher than the .243-value G7 BC of the 175gr SMK.
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Tags: Ballistic Tip, ballistics, Rifleshooter.com, Sierra Bullets, SMK, TMK
Congratulations, Sierra has invented the 175gr Sierra Amax. If they really want to make a nice bullet take the profile of their 7mm 175gr SMK (9+ ogive) apply that to the 175s and heavier in the .30cal line and you would have nice shooting bullets. Doing the math it would be the same or slightly better than the Berger hybrid line.
If measurements varied from .400 to .407 , the .007″ value is extreme spread, difference from the two most extreme values .
Variance is the average of squares of the differences from each value to the average value .
SD is the square root of variance.
Editor: Variance (in weight, length etc.) is standard english-language description of the difference between two numbers, sizes, or properties. That is the primary definition of the word according to all dictionaries. However, you are correct that, in statistics terminology, as an alternative usage, variance is used to describe the square of the standard deviation. To eliminate confusion we have changed the article to use the term “extreme spread” rather than variance.
Not Impressed, what is 9+ ogive?
Shot at our range a couple weeks ago at 1000 they shot inside the standard 175 MK and two minutes higher. First test they did very well. Like any bullet, shoot and see, you might be surprised.
I tested these bullets against my standard 308 load with the SMK, lapua brass SMK and 43.1 grains give sub half moa, 43.8 grains in Lapua brass with the SMK’s sitting 15 off the lands had sub 3/8th moa. I know what the article is saying but I have had success, now waiting for the 6.5’s.