Wednesday, January 28, 2015

The Taurus Curve Bends the Rules of Pocket Pistol Design - New Gun Review


Taurus Firearms


One of the more challenging aspects of concealed carry is comfortably concealing the firearm you choose to carry.  We humans tend to be curvy, and firearms tend to be flat with squared edges.  The Taurus Curve addresses this conundrum with a patented curved grip frame designed to conform to the natural contours of the wearer.

When designing The Curve, the Engineers at Taurus created a concealed carry firearm that reduces "printing" while increasing carry comfort, regardless of where The Curve is  carried on the body.  Additionally, the design team removed all the sharp edges to further enhance comfortable carry.  The current Curve model is gently curved to accommodate the right-handed shooter carrying on the right side of the body.

The double action only Curve is chambered for the 380 Auto cartridge and has a capacity of 6+1.  The dimensions and weight of the Curve make it a good choice for discreet carry.  The polymer grip frame also includes an industry-first integrated LED light and laser sight.  The Curve is made in the USA and has a retail price of $392.

I learned about The Curve back in June 2014 when I noticed a forum posting announcing that Taurus had received a patent for a body contoured handgun design.  At the time, I thought it was interesting and filed it away in my mind thinking it would probably be years before we actually saw the handgun on the market.  What I wasn't expecting was the product announcement from Taurus in November 2014 announcing that The Curve was available for pre-release review and would be shipping in the first quarter of 2015.

Designed with Purpose In Mind
Holding The Curve in my hands for the first time, I quickly realized it was much more than just a handgun with a curved frame.  I could see that significant time and attention went into the design to make The Curve as concealed carry friendly as possible.  Some design elements were more welcome than others, but I could see why each element was included by the designers.  I'll touch on the features I found most interesting.

The Curve has rounded edges on every surface that may come in contact with the body when carried.  This "carry melt" treatment extends all the way to the muzzle.  At first, I was concerned that the angled muzzle crown on the barrel would have a negative impact on accuracy, but closer inspection revealed that the barrel rifling stops at the start of the angle cut and has no adverse effect on the accuracy of The Curve.

To keep The Curve as thin and snag free as possible, Taurus removed, or redesigned, the controls typically found on the sides of a semi-auto pistol.  The Curve does have a slide lock for last round hold open.  Taurus has moved it inside the frame which requires removing the empty magazine or inserting a loaded magazine to allow the slide to return to battery.

The magazine catch and magazine release have been integrated into the magazine base plate.  The magazine catch locks into a recess molded into the frame.  While very different than the arrangement found on other semi-autos, the system worked well in my testing.  My initial fears of the magazine dropping out of the frame while gripping the pistol proved to be groundless.

The slick-sided Curve has no grip texturing on the sides of the grip.  Small patches of moderately aggressive texturing are molded into the center of the front and back straps.  These small patches of texture maintain the integrity of the "carry melt" while providing sufficient grip to control The Curve while shooting.  I have medium to large hands and could almost get two fingers on the front strap with the pinky curled under the magazine base plate.

Taurus lists a trigger pull weight of 5 to 7 pounds for The Curve.  Before heading out to the range for the first time, I measured the trigger pull weight and practiced dry firing.  As you might expect with a firearm designed for concealed carry, the trigger pull is quite long.  My trigger pull gauge confirmed the trigger starts out at 6 pounds and breaks at 7 pounds.  The trigger was smooth with no noticeable stacking, hesitation, or gritty feeling.

The Curve arrives with a removable belt clip attached at the rear of the frame.  A trigger shield, that covers both the trigger and laser activation switch, is also included.  The belt clip and trigger shield can be used in lieu of a holster for those that wish to carry in the waistband.  I contacted my friends at Remora Holsters and they quickly built a pocket holster for The Curve.  I was all set for the range.  Before we hit the range, I'd like to include a mini review of the LaserLyte UTA-CU.

LaserLyte UTA-CU
The Curve features an integral laser and light module from LaserLyte.  The tri-mode module can be set to project light only, laser and light, or laser only.   The activation switch is located on the right side of the frame, directly in front of the trigger guard.  A light push forward on the activation switch turns the laser module on.  Pushing the switch forward a second time turns the laser module off.  Holding the switch forward for 5 seconds switches between the three projection modes.  The module will automatically turn off after 6 minutes.  The module has a 3 year warranty and can be easily replaced in case of failure.

The 5MW red laser is the most powerful allowed by law.  The laser is easily adjusted for windage and elevation changes.  The 25 lumen LED light is bright enough to provide low/no light visibility improvement.  The module is powered by three 357 silver oxide batteries that are commonly available in a three pack for less than $5.  The external battery access door is located directly above the white LED lights to facilitate easy battery changes.

Battery life is dependent on the projection mode of the laser module.  LaserLyte provides the following guide on battery life.
Laser only:  5 hours
LED only:  1.5 hours
Laser and LED:  1 hour

I put the laser module through hundreds of on-off cycles and frequently swapped between the three projection modes.  I used it enough that I had to change the batteries.  With all the use and recoil exposure from shooting, the laser remained focused and on target.  It appears to be a robust addition to The Curve.


The Curve On The Range
I used the laser sight to test the inherent accuracy of The Curve from 10 yards.  Standing off hand groups were very good.  If I took my time, 12 shot groups under two inches were the norm.  At this distance, the bullets cut clean holes in the target which negated my concern that the angled barrel crown would cause bullets to yaw or tumble.

To keep The Curve as smooth and snag-free as possible, Taurus created the Bore-axis Sighting System to replace traditional sights attached to, or machined into, the top of the slide.  The Bore-axis Sighting System consists of three white lines on the rear of the slide that mimic the cross hairs of a scope.  Using the sighting system requires superimposing the cross hairs on the target before firing.  My initial attempts to use the sighting system resulted in more left drift than I expect to see on the target.

I ultimately ended up using the loaded chamber indicator, on the top of the slide, as my sighting system.  My accuracy with the Curve improved.  I continued to use the loaded chamber indicator as my sight for all my shooting with The Curve.

Though more than 400 rounds, The Curve proved to be very reliable.  I ran a variety of full metal jacket round nose, flat nose, and jacketed hollow point ammunition with bullet weights ranging from 85 to 102 grains though The Curve.  The only failures to feed or extract happened when using Blazer aluminum cased ammunition.  I have found that it's not uncommon for small handguns, like The Curve, to have a distaste for certain brands of ammunition.  As long as the reliability issues are isolated to a specific brand of ammunition, it's easy enough to avoid them.

I found The Curve very comfortable to shoot.  Recoil was modest and I didn't experience any trigger finger slap or pinch.  I think the slightly wider grip width, than most of the other small 380s on the market, made the difference in shooting comfort.  For me, The Curve felt best when I shot it with one hand.  Trying to squeeze a second hand on the grip didn't improve my accuracy or control.  Those with smaller hands may have different results and preferences.  The belt clip is mounted high enough on the frame that it doesn't make contact with the shooter's hand.   

The six round magazines are very easy to load, but they do require a firm push to seat them in the magazine well.  If you watch the range video, you may notice the habit I developed of keeping my fingers under the magazine base plate and hooking my thumb over the slide to squeeze the magazine into place.  A firm push on the base plate will accomplish the same result.  

After assuring myself The Curve was reliable, I carried it frequently for several weeks.  I carried it clipped inside my waistband with the trigger shield in place.  I also tried it in my right front pocket with only the trigger shield in place.  While this method was the most comfortable, I have a personal bias against open muzzle pocket carry.  My preferred carry method is in a pocket holster without the trigger shield.

Taurus set out to create a small semi-auto that concealed well, and was comfortable to carry all day - every day.  The Curve fulfills those goals quite well with a long list of features that will appeal to those shopping for their first concealed carry firearm, or those looking for something a bit smaller or more discreet than their current carry handgun.  Taurus anticipates shipments of the Curve to start in February so watch for them at your local firearm retailer.

 


The Curve Ships with Two Magazines and Trigger Shield
The Taurus Security System is Integrated in The Curve









The Long Double Action Trigger Pull
Requires 6 Pounds to Start and Breaks at 7 pounds











 

      


 


Sample Velocity Data From The Curve
















 Link To Review Video On YouTube




Thursday, January 15, 2015

Challenges to the Continuing Evolution of Terminal Ballistic Testing: A Mathematical Solution for Equivalence

Literally pounds of recovered bullets have been labeled and cataloged for model data and future reference.

Early on in my adoption of Clear Ballistics Gel as my ballistics testing media of choice, I realized that it wasn't an exact substitute for 10% ordnance gelatin. On the other hand, it offers the advantages of visibility, re-use, and stability at all temperatures. Since I conduct and publish a large volume of tests and test outside in all types of weather, Clear Ballistics Gel was a good fit for my budget and testing constraints.

I can't thank Charles Schwartz enough for all the time and effort he's invested in me, as well as his model development. He's been great to work with and a wealth of knowledge on both the art and science of terminal ballistics testing.  Working together, Charles and I embarked on a multi-year project to determine if it was possible to create a "conversion factor" to bring the Clear Ballistics test results in line with test results observed in 10% ordnance gelatin.  Charles has graciously submitted the following article to detail the results of our work.

On Friday, November 29th, 2013, Bruce published my first guest blog on the continuing evolution of terminal ballistic testing especially as it relates to alternative test mediums like physically associating gels (PAGs). As that technology continues to mature, significant challenges have arisen, the most important being that of equivalence of PAG test mediums to other terminal ballistic test mediums—namely the present testing standard of calibrated ten percent concentration ordnance gelatin.

Near the end of that article that I wrote:

As illustrated above, one of the benefits of using the QAS model is that it can be used to confirm a test result or, in the case of a test bullet exiting the test medium unexpectedly, to “save” the test by using the available data (impact velocity, retained mass, average expanded diameter) to predict the terminal performance of the otherwise “compromised” test event. Since I wish to substantiate this opinion further than I have in this article, I am extremely interested in conducting a detailed statistical analysis of Clear Ballistics Gel test data in order to determine just how closely the QAS bullet penetration model correlates to actual terminal ballistic behavior in that test medium. I hope to share the results of that analysis later.

Well, that analysis is now complete and I have to say that I am pleasantly surprised and quite pleased with the results. Of course, since I do not conduct terminal ballistic testing using Clear Ballistics Gel, none of this would have ever been possible without Bruce’s diligent testing and evaluation and his meticulous attention to detail.

To begin with, a brief review of the material properties of Clear Ballistics Gel and how they influence terminal ballistic performance is in order. Clear Ballistics Gel is a synthetic gel composed of a paraffinic oil and a blend of elastomers that has a density of 0.850 gram per cubic centimeter. Because the density of Clear Ballistics Gel is somewhat lower than calibrated ten percent ordnance gelatin, it calibrates using a 5.2-grain, 0.177”-caliber BB at 591 ± 13 feet per second, with slightly deeper penetration than what is seen in the biologically-derived ten percent ordnance gelatin so widely accepted and used in the terminal ballistics research community, international militaries, and our major ammunition manufacturers. What this means is that JHP bullets fired into Clear Ballistics Gel tend to expand a little less and produce slightly greater penetration than they would in calibrated ten percent ordnance gelatin. This is because the forces that drive expansion and ultimately dictate how far a bullet will penetrate are primarily dependent upon the dynamic pressure produced upon the bullet’s impact with Clear Ballistics Gel.

Dynamic pressure is a function of the impact velocity of the bullet and the density of the medium being struck and penetrated by the bullet. When used to compare the respective dynamic pressures produced by Clear Ballistic Gel, whose density is 0.850 gram per cubic centimeter, and ten percent ordnance gelatin, whose density is 1.040 gram per cubic centimeter, the equation for dynamic pressure, P = ½ρv2, shows that Clear Ballistic Gel should produce 18 - 20 percent less dynamic pressure than ten percent ordnance gelatin at any given impact velocity. The significance of this is that terminal ballistic test results obtained in Clear Ballistic Gel and calibrated ten percent ordnance gelatin are not directly comparable to one another.


The mathematical model found in Quantitative Ammunition Selection makes it possible to directly compare terminal ballistic test results obtained in Clear Ballistic Gel and calibrated ten percent ordnance gelatin. By setting the QAS model parameters for the ultimate tensile strength, σ, and density, ρ, of calibrated ordnance gelatin, and using the impact velocity, average recovered expanded diameter, and recovered bullet weight of a bullet fired into Clear Ballistic Gel, it is possible to “convert” those results obtained in Clear Ballistic Gel into equivalent penetration depth—and wound mass—as they would have occurred if the bullet had been tested in calibrated ten percent ordnance gelatin. It is also possible, using the QAS model, to predict and confirm projectile penetration depth—and wound mass—in Clear Ballistic Gel by setting the QAS model parameters for the ultimate tensile strength, σ, and density, ρ, to ρ = 0.850 gram per cubic centimeter and σ = 135 Newtons per square centimeter.


There has also been one other recent development. During a consultation that I participated in over the last 13 months, it became necessary for me to develop an equation for my own use that was based upon the exponential structure of an engineering equation that would permit the expedient prediction of projectile penetration in soft tissue surrogates with a high degree of accuracy. That equation, a highly modified and rather abbreviated version of the THOR armor penetration equation used to predict the penetration and retained weight of fragments and low-aspect (L/D < 3) projectiles after striking and perforating various metallic materials, was evaluated against Bruce’s Clear Ballistic Gel test data and found to produce accurate predictive results. Later, I also evaluated the modified THOR equation against the 777 points of calibrated ordnance gelatin test data that I have been continually amassing over the last three years from ten independent, published and unpublished sources, composed of various ammunition manufacturers, laboratories, and law-enforcement agencies. I found, with the addition of the correct exponential variables, that the modified THOR equation cold also produce accurate predictions for bullet penetration in calibrated ten percent ordnance gelatin. As a result of those evaluations, the modified THOR equation is now included in its very own chapter complete with examples, in the latest edition of Quantitative Ammunition Selection.

So, what were the results of the statistical analysis?

Over the last thirteen months, Bruce and I were able to assemble 103 data points taken from Bruce’s tests conducted in Clear Ballistic Gel. Of those 103 data, fourteen had to be discarded due to conditions (bullets that exited test blocks, bullets that tumbled during the penetration event, etc.) that were beyond our control. The remaining 89 data were then used to establish a correlative relationship with each model and to develop the following analytical perspective.

The analysis results for the QAS bullet penetration model and modified THOR equation are found in the table below:


Statistical analysis results for the QAS model in its “conversion” mode for translating test data obtained from Clear Ballistics Gel into their calibrated ten percent ordnance gelatin equivalent (QAS @ σ = 100, ρ = 1.040) are found in the second column of the table, results for the QAS model in its “predictive” mode for Clear Ballistics Gel test data (QAS @ σ = 135, ρ = 0.850) are found in the third column, results for the modified THOR equation used in its “confirmatory/predictive” mode for Clear Ballistics Gel test data are found in the fourth column, and results for the modified THOR equation used in its “confirmatory/predictive” mode for calibrated ten percent ordnance gelatin are found in the fifth column.

Despite the relatively small sample size for the Clear Ballistic Gel data, I am pleased by the outcome of this analysis. While I would like to have had at least one thousand test data against which to compare each model, practicality dictates that a sample population of that size would take a tremendous amount of time—not to mention money—to compile. What these results tell me is that the QAS bullet penetration model and the modified THOR equation can be used with high confidence in both the conversion of Clear Ballistic Gel results to equivalent yields in calibrated ordnance gelatin and in their respective “confirmatory/predictive” modes for both terminal ballistic test mediums.

So, in spite of the challenges to the continuing evolution of PAGs, there is an answer to the issue of incomparability of terminal ballistic test mediums—mathematical modeling.

As always, Quantitative Ammunition Selection is available domestically and internationally in hardcover, paperback, and eBook formats and may be purchased at www.quantitativeammunitionselection.com.

Just select the appropriate link found on the lower third of the ‘Home’ page for the format that you want.

—Charles Schwartz