TESTED: Sierra 7mm 175-Grain MatchKing X

New to Sierra Bullets’ MatchKing X (MKX) line is a 7mm 175 Grain bullet! After splendid results with the 6.5mm 142-grain MKX and .30 caliber 200-Grain MKX, we decided to put the 7mm to the test in a 7 SWC!

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About the 7mm 175-Grain MatchKing X

The 175-grain MKX is a mirror image of the famed 175-grain MatchKing bullet, sharing the same ogive profile and external dimensions. This means there is no need for seating die adjustments when switching between the two! Its high ballistic coefficient (0.597 G1) mimics MatchKing performance with the addition of devastating expansion.

To learn more about the new MatchKing X line from Sierra Bullets, check out our previous coverage!

From Sierra Bullets:

Designed for the modern shooter, MatchKing® X (MKX) represents the next evolution of our legendary MatchKing® series—combining deadly terminal performance with the proven accuracy and shot-to-shot consistency that MatchKing is known for. Redesigned with a softer lead core and a tapered nose, MKX bullets are held to the same tight accuracy standards as the original, now with enhanced terminal performance. Whether you’re at a match or in the field, MatchKing® X is built to bring home the prize.

1. Boat Tail

The boat tail design reduces drag and enhances ballistic performance compared to other flat base counter parts – an essential element to legendary Sierra accuracy.

2. Soft Lead Core

MatchKing X bullets feature a softer lead core than the original MatchKing bullets, promoting reliable and lethal expansion on game.

3. Tangent Ogive

Tangent Ogives provide high ballistic coefficients, smoother feeding, and excellent in-flight stability. Tangent ogives are also inherently easier to tune and less finicky ensuring consistent accuracy.

4. Tapered Jacket

Engineered with a unique draw-and-trim process, MatchKing X features a thick copper jacket through the body for enhanced durability while a tapered design at the mouth ensures reliable and devastating expansion.

Load Data and Results

I paired this new bullet with my incredibly accurate 7mm SWC rifle, utilizing the same powder and cases I had previously.

I loaded a progression of different charge weights of Vargets in virgin Alpha Munitions cases.

I found a load I liked at 2,650 fps, shooting a 0.435” five-shot group at 100 yards.

Clear Ballistics Gel Testing

While synthetic ballistics gelatin will not 100% reflect what a bullet will do to a human or animal, it provides us with valuable data and allows us to compare the performance of different bullets and different loads. It is also fun to watch via high-speed camera (Edgertronic SC2+)! American-made Clear Ballistics Gel is reusable. It can be melted down and utilized again for even more tests.

We set up a sound trigger to activate the high-speed camera, firing from a steady position into a row of gel blocks. As the rifle was zeroed for 100 yards and we were shooting at far less than that, I used a black marker to create an aiming point to accommodate the appropriate offset.

The first block convulsed from the explosion, a massive 11-12” wound channel demonstrating the bullet’s capabilities. The MKX traveled well into the second gel block, but if you prefer further penetration over violent expansion, a Barnes monolithic bullet may be a better choice.

Overall, I was extremely impressed with the bullet’s performance, expanding approximately 75% in diameter with 53% weight retention at 2,759 fps.

Lab Results

Kyle Shields has become our primary “bullet lab technician,” taking a variety of lab measurements from a sample of 175-Grain MKX bullets to evaluate their consistency.

The average length was 1.4271” with a standard deviation of 0.0027” and extreme spread of 0.0098”.

The average bullet weight came in at 175.101 grains — very accurate— with a 0.0822” SD. Perhaps most impressive were the SD and ES figures for the bullet diameter.

The average diameter measured 0.28415” with an SD of 0.00004” and ES of 0.00010”. This may be our most consistent bullet diameter result to date!

Conclusion

Sierra’s 7mm 175-Grain MKX Bullets combine match accuracy and incredible consistency with intense expansion. I have no reservations about using this bullet for hunting and pushing it far.

Sierra’s forethought in mimicking the performance of their traditional MatchKing line makes it easy for competitive shooters using a traditional MatchKing to reload the same weight bullet without having to adjust seating depth. Loads will also be very similar!