POLYURETHANE PISTOL TARGETS

Transcription

1 TEST REPORT POLYURETHANE PISTOL TARGETS

2 Polyurethane Targets Test Report Outline These tests were conducted to determine the effectiveness of Polyurethane (Poly) targets for indoor pistol competitions. Polyurethane has often been considered a safe indoor material for reactive targets, although it is not very commonly available in commercially made targets. These tests looked at the projectile path and speed, through poly targets. The premise being that if even low power rounds still penetrated in a straight line through targets that are free to move, then the ricochet risk is extremely low. Similarly, if projectile speed after it has penetrated the target is not slowed by a large percentage then again the ricochet risk is extremely low. Target Material While polyurethane is available in many different formulations; these tests were conducted by using a cold-casting polyurethane, primarily because it is commercially available in Sydney and easily cast at room temperature, using simple wooden moulds. The material is Erapol CCM75A available from Aldax Moulds in Mortdale, Sydney. This material has a surface hardness of 75 durometer, Shore A, when cured. The test target is a circular plate cast 12mm thick with one layer of 300 g/m2 fibreglass chopped strand mat inserted during casting. The fibreglass layer improves the beam strength and resists the tendency to sag when mounted about degrees from vertical, as a hinged plate. Test plate, shown at right, is 175mm diameter and freely hinged to a wooden target stand. A second test target was also used, made of the same material and same thickness, but without any colour or reinforcement. This allows the bullet penetration paths to be visible.

3 Test Equipment The Chronograph used is a Chrony brand, Alpha Master version fitted with lights for indoor use. It was positioned 5 metres downrange from the shooter s position. Firearm Test firearm was a Smith and Wesson Super 9, semi-auto pistol in 9 x 19 calibre (9mm Luger) with a 5 in (127mm) barrel, used for club and IPSC competition. This type of pistol represents the minimum power firearm that would be used with this type of target. Test Ammunition Test ammo was hand loaded using 115 grain and 135 grain poly coated lead projectiles. This emulates the typical ammunition used by club members in both the club s firearms and member s own firearms. Loads were varied from those exceeding IPSC minor power factor loads (125) to loads well below minimum power. Procedure The test target was mounted immediately before the chronograph, as shown in the photo. As the target was hinged, it could be lowered out of the line of fire. This allowed the projectile velocity to be checked, both with and without the target (simulates before and after penetration), without the need to move the shooter, the firearm or chronograph.

4 Velocity To check how penetrating the polyurethane target affected bullet velocity; tests were conducted shooting through a chronograph, both with and without the polyurethane target placed between the firearm and chronograph. 5 shots were fired for each test, both with the target in place, measuring projectile velocity after it penetrated the target, and with the target lowered, measuring projectile velocity with no target interference. Two loads were fired to test the effect of typical 9mm pistol loads and a much weaker load - 1. A load that exceeds IPSC Minor power factor (bullet grains x velocity in ft/s, divided by 1000 = 125 min.) and would be typical of both club and member reloads for competitions using these targets. This is the load using the 135 grain projectile shown in the table below. Factory 9mm ammunition (Federal Cartridge American Eagle brand) using 124 grain projectiles has been chronograph tested to very similar power ( IPSC power factor). 2. A load that used a lighter projectile and was well below IPSC minimum power factor to see if a lower power factor, and energy at the target, affected its penetration. This is the load shown with the 115 grain projectile. The reasoning being that as the projectile gets lighter and applies less energy to the target, the likelihood of ricochet increases, so lighter loads should be more likely to show up any tendency towards deflecting bullets. The table below shows that penetrating the target reduces bullet velocity be some 9 to 12% and reduces the energy available at the target by 17 to 23%.

5 Penetration Close up photo of a noncoloured polyurethane target, showing the bullet paths as straight dark lines. The lines are not parallel because this target has been shot in different mounting positions. Left most penetration (marked as 1) shows target when supported on a hinge type mount where it is about 15 degrees from vertical. The centre and right penetration holes (marked as 2) were with the target hanging vertically. Bullet holes The polyurethane material stretches to allow the projectiles through the material, and returns to its relaxed state, except that a very small bullet hole remains, less than 0.5 mm in diameter. A straightened paper clip (0.75 mm diameter) is a tight fit in the hole left by a 9mm bullet. Even with many holes close together the material still retains nearly original strength and flexibility. Close up of the bullet entry side of test target 1 2

6 Close up of the bullet exit side of test target, showing very small holes remaining. Straightened paper clip is shown in upper centre hole. Observations Typical 9mm loads fired from a typical target competition pistol will easily penetrate a 12mm thick polyurethane target. The target stretches to allow the bullet to pass, leaving behind a very small hole. Targets can retain their shape and strength even after dozens and probably hundreds of rounds. Targets can be reactive without being a ricochet risk. All shots that penetrated the test target also provided enough energy to knock the hinged target down, while only reducing the bullet velocity about 10-12%. All shots penetrated in a straight line through the target material, with no sign of deflection. While all projectiles applied sufficient energy to knock down the freely hinged target, the bullet penetration path shows the bullet is well past the target before it starts to fall. Reduced load rounds still easily penetrated indicating there s a useful safety margin when firing typical 9mm or 38 calibre rounds. Only round nose or conical point bullets were tested. Only these bullets should be recommended. Hollow points were not part of this test, but have been tried and while they penetrate just as easily they have the tendency to remove some material from the target leaving a larger hole, thereby shortening the target s useful life. P. W. Dawson Secretary Shooting Academy Club Inc. 23 March 2013