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10mm 185gr Xtreme Penetrator Accuracy

10mm Auto Ammo
10mm auto ammo test

Kimber 5″ and Glock 4.5″

In a previous POST (click here) we described our gel test of the Lehigh Xtreme Penetrator (XP) in 10mm.  We also described our attempt to find a suitable load using a Hodgdon powders.  Candidly speaking, we use many powders from this manufacturer and it would be helpful for inventory management to stick with a powder already in stock.  Unfortunately, we could not find a load that met our standard for accuracy as our best string showed a velocity standard deviation of 16 FPS.  We also noted that even using small incremental increases in powder between each group resulted in no clear winning formula- or a window that would be suitable for production.  Specifically, when producing ammunition on a progressive scale (and not weighing each charge), there will be a small variation in the powder charges that are thrown.  This range is often as small as +/- .05 grain and in some cases as much as +/- .15 grain depending on the powder used and the cartridge being loaded.  Note that extruded powders are notorious for less-than-perfect metering properties.  This background is important because not only is it important to find a powder charge that results in consistent velocity and pressure, but it is also important that the chosen load is not right at the cusp of a sharp increase or decrease in velocity.  For example, if your load shows a consistent velocity (low SD) at 20.0 grains, but shows either an increase in average velocity or an increase in spread at a charge of 20.1 grains…it is not reasonable to consider your load of 20.0 grains an acceptable spec for production.  Alternatively, we attempt to find a powder and charge that yields a consistent velocity at the selected charge, as well as within a close range of charges.

After switching to an Alliant powder that is used in our highly accurate 180 FMJ load, we quickly knew a great load was close.  After only 5 loads we not only had a load with an SD of < 5 FPS, but one with singled digit SDs on either side of that load.  This is perfect for the field and in production.

10mm auto accuracy

25 Yards Accuracy Test- First and only groups

Initial accuracy tests were promising.  Using a simple bag rest at 25 yards resulted in a 1.6″ three-shot group from a 5″ Kimber 1911.  The results from our Glock 20 were not as impressive, but shooter error can explain at least a portion of this group size- even in 2019 I have a strong preference to John Browning over Gaston Glock.  These two groups were the only rounds put onto paper other than one shot from each gun at approximately 12 yards to establish a rough POI for the longer shot.  Future tests will include multiple 3 shot and 5 shot groups for bragging rights.

Conclusion

Based on our gel test results , the consistent velocities and accuracy potential described above, and Lehigh Defense’s reputation, this 185gr bullet will become part of our 10mm offerings.

 

 

Andy Steinel 9/26/19

 

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