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10mm Auto- Gel and (Initial) Accuracy Testing With 185gr Lehigh Defense Xtreme Penetrators

By 09/18/2019July 1st, 2024Ammunition Testing
10mm Auto Gel Test

Lehigh Defense

There is, and has been, a lot of buzz around Lehigh Defense’s high-tech bullets.  Controlled Chaos, Controlled Fracturing, and Xtreme Penetrators are the first few technologies that come to mind.  One can’t help but to wonder if there is merely marketing at play here or if these bullets’ performance is driven by significant R&D and testing.  “Gimmicky” is a word sometimes used to describe the Xtreme Penetrators- or what is often referred to as “those bullets with the cross on top.”

10mm Targeted

Here at Steinel Ammunition, we really wanted to jump into the 10mm Auto market and take advantage of what I see as a great opportunity.  From a performance standpoint, there are already some excellent options from ammo manufacturers with proven records in the 10mm arena.  You can probably think of at least two off the top of your head.  However, our approach to hunting ammunition allows us to develop and offer loads with similar (if not better) performance often at a significantly lower cost.  We offer loads for three distinct applications:

  1. Big Game Hunting– Hunting with larger revolver rounds is not uncommon.  With the advent of mega magnums like the 460 and 500 S&W, handgun hunters often hold more energy than their long-gun wielding counterparts.  The 10mm is a little different: while often compared to a 41 Magnum the 10mm lacks the case capacity to challenge more popular options like 44 Magnum and 45 Colt.  That being said, it is still a very capable big game hunting cartridge given the right load and adequate shot placement.  Hard cast loads offer the ability to shoot heavy-for-caliber bullets and achieve impressive penetration.  Jacketed Hollow Points offer significantly more expansion at the expense of penetration.  Other options include soft points, Solid Copper Hollow Points, and high-tech bullets such as the Lehigh Xtreme Penetrator.
  2. Self Defense– 10mm in a semi-automatic pistol offers a great option for self defense.  This applies to your CCW as well as a sidearm when hiking.  Depending on what you intend to defend yourself from, proper bullet weight and bullet technology is critical.  We consider the FBI standard a great guideline for self defense against “thin skinned” bad guys.  Specifically, over 18″ of penetration in ballistic gel is not suitable for self defense in crowded environments.  Our 140gr Maker Solid Copper Hollow Point is a great option in that it penetrates 13″ in gel, and expands very well (will post test results elsewhere).  For protection against big game 2. above applies.
  3. Target shooting– You can shoot 40 S&W from your 10mm and there’s a lot of watered down 10mm target ammo out there.  On Instagram (steinel_ammo) we often use #noboringammo to boast that we don’t bother with FMJs in 9mm, 223, and other common calibers.  To be honest this is as much of a function of capabilities as it is interest.  If we could produce quality 124 grain 9mm rounds by the million, charge a fair price, and still make a margin….we would.  But alas- this isn’t going to happen in our current 6k sq ft facility 🙂 For now we will limit our target rounds to the calibers that make sense economically, such as our vintage military line and even the modern 10mm Auto.   In staying true to #noboringammo- we’ll keep velocities >1,200 fps with a 180gr RNFP through 5″ barrels.

Loading Notes

The Lehigh Xtreme Penetrator we tested was 185gr.  A flat seating plug was used for loading and created no bullet deformation or bullet offset in our Starline cases.  The cross profile fed as smoothly as a RNFP into our Glock and Kimber 1911.  When setting bullets on top of charged cases, I did note that the bullets seemed to fit quite deeply inside the new Starline cases with even a modest flare.  That being said, neck tension was sufficient.  Our tested loads were close to compressed so a bullet setback test may not prove meaningful, but using an inertial bullet puller showed adequate bullet hold.  A sample of 10 bullets weighed between 185.06 and 185.20 grains.  Overall bullet length is .752″ and there are four driving bands.  From the bullet base to tip, each band has a diameter of .397″, .398″, .399″, and .399″.

185gr 10mm Lehigh

Lehigh Defense’s 185gr 10mm Xtreme Penetrator

Why Test the Xtreme Penetrator?

The reason we wanted to test the Lehigh Xtreme Penetrator is because of the results of our last 10mm gel test.  We tested the 165gr .400″ Maker SCHP, and we found that the current design could not handle the tested velocity of 1,315 FPS from our Glock 20.  It lost all of its petals and penetrated 23″ of gel.  It was impressive how this bullet traveled straight, lost one petal approximately every 7 inches and penetrated quite a bit of calibrated gel.

10mm Recovered Bullet

165 grain 40 S&W Bullet at high-end 10mm Velocities

However, this isn’t the result I had hoped for.

In the 10mm gel test using the 165gr SCHP, I had hoped to see results similar to the 140gr SCHP, but with more penetration- even at the sacrifice of some expansion.

10mm SCHP Gel Test

Maker 140gr SCHP in 10mm Auto- Excellent performance for self-defense

After sharing these results with Paul at Maker, he plans on reformulating a more 10mm-oriented .40o” hunting bullet- perhaps in the 180gr weight range.

I was told by several people that the XP bullet would probably offer unimpressive penetration and expansion.  They posited that it was too light to penetrate like a hard cast and it was a monometal so it wouldn’t expand.  “It will drill a clean hole” was contrasted against Lehigh’s claims that the wound channel would be superior to its hard cast counterparts.  Based on the reputation of Lehigh and how quickly their company seems to have grown over a short period of time, I was inclined to believe their claim.  My initial thought was that the unique profile must provide some sort of advantage.  I had plenty of experience with gel testing the Inceptor fluted RN bullets  (“ARX”), and a limited amount of experience with field tests, and knew that those flutes displaced gel as they were designed.  The Lehigh cross profile seemed somewhat similar but even more radical than the ARX flutes.

Enough Already…Shoot Some Gel!

Now for the fun stuff.  Our bare gel blocks were impacted at 1,114 FPS from a Glock 20.  Penetration was 27.5″ and the wound channel began to develop a large, triangular pattern after 9″.  These blocks are approximately 6″ X 6″ X 21″ so with two stacked together, we had 42″ of gel to work with…if the shooter can keep the projectile from veering out of the blocks.  In this case the bullet showed no signs of yaw and stayed a straight course for the entire 27.5″.

To say that the wound channel was impressive is an obvious understatement.  You can see from the pictures that the gel was severely torn- with a majority of the damage incurred between inches 9 and 18.  We plan on doing more testing, but this bullet clearly offers more than marketing hype.

Accuracy Testing- Load Development

We hit a bit of a speed bump here.  Our 10mm gel test using the Lehigh Xtreme Penetrator was illuminating.  However, our first two powders tested did not exhibit a tight enough SD to warrant accuracy testing at 25 yards.  One powder showed no groups better than 16fps SD and the other yielded no groups lower than 20fps.  The group sizes on our target also indicated that there was some more work to do here.  The team at Lehigh seems very willing to help us find a consistent load so I look forward to putting in more testing in order to find something that can group consistently.  After designing and testing our own .458″ 325gr Solid Brass RNFP, we were not caught off guard with the difficulties in finding the perfect load using a monolithic bullet.



This is our first attempt at shedding some light into our testing processes here at Steinel Ammunition.  Please let us know if you have any questions or comments on the information we are sharing.  We’ll keep sharing if there’s interest and we’ll scrap the idea if you merely want the time without learning how the watch is made.


Andy Steinel

Join the discussion 5 Comments

  • Gary says:

    I think a hard cast bullet with the Lehigh Xtreme Penetrator front end flutes would be a great product to develop and sell. It should be fairly easy to fabricate a bullet mold that incorporates the flutes so you could make your own bullets. The cost would be cheaper than machined copper and the bullet mass would be greater than solid copper. A heavier bullet would allow for more powder in the case to yield greater velocity and greater momentum. The bullet would combine the advantages of the fluted front end design and the mass and affordability of hard cast lead. What’s not to like? There may be patent infringement concerns, but they have a time limit.

  • Alan watkins says:

    I would be interested in the 185 grain extreme penetrator, in 10mm. I hand loaded a 200 grain extreme penetrator in 45 super, using starline brass and Hogdon Longshot. Started at 9 grains and worked up to 11 grains. Actually it topped out at 12.5 grains, at low to mid 1300’s fps. Of course I had a kkm barrel and a 24 lb. Spring in my Glock 41. It would be good if someone would market the 185 grain for 10mm at 1350 ro 1400 fps.

  • Matthew Trach says:

    Hello, do you still offer the 10mm 185 grain extreme penetrator? I didn’t see it listed with the other 10mm ammo.

  • Will says:

    Thanks for posting your data. When i first saw the XP later XD many years ago I knew they for real. Anyone who has ever seen what power washer can do to a hand knows water is lethal. Gimmick bullets are fairly easy to spot without wasting money. The cool looking bullet with scalpels cuts beautiful holes. Hey they would work 100% on muscle beach. But what works in the lab does not always work in the field. The Lehigh however IMO is one of, or even the best barrier blind bullet. Short range defense, glass, wood, dry wall, sheet metal does not matter that bullet will out perform a HP 8 out of 10 times over a vast array of factors or circumstances. FBI claims 37% failure for HP bullets. This bullet “type”, hydraulic is not new but over 100 years old. The hydraulic bullet was rejected by the Hague in 1901 IIRC and in the Geneva Convention as not humane. Well at least they dont die later of lead poisoning. The problem I experienced was accuracy and bands. But they were not designed for target, match. The accuracy at 25 yards is not really a big factor. The XD is my carry bullet. I also carry one mag of ARX.

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