![]() ![]() Numerous manufacturers of the AR-15 offer their guns in civilian chambering using SAAMI not NATO specs. But the civilian spec ammo can be shot in military actions, at a slight velocity loss due to the relatively long free bore of the military weapons. High pressure and possible mechanical failure of the action is possible due to high pressures of the military ammo. The point is to use CAUTION when firing NATO spec ammo in civilian weapons. Not a concern for the sportsman, with the camming action of the bolt action rifle. ![]() NATO ammo is fired from looser chambers to ensure extraction during the firing cycle of semi and full automatic weapons. Military ammo uses military specs using a different test procedure than SAAMI, with NATO pressure rating appearing more conservative than SAAMI. Therefore, you can shoot your sporting loads in a military rifle, but not the NATO rounds in a civilian gun, unless you have a gunsmith add some free bore. Point two is that most military loads operate at higher pressure than their civilian counter parts. The effect is that a load that performs safely in a chamber with free bore, will produce higher chamber pressures in a tight chamber with little or no free bore and can be dangerous to the gun and shooter. Military chambers are ‘looser’ to promote more reliable operation in military select fire weapons. Another aspect is that the sports SAAMI chambers are tighter, enhancing accuracy, with less cartridge case expansion. ![]() In civilian chamberings the bullet is in contact with rifling and the peak pressure arises early on as the gases must overcome the cutting of the lands into the bullet and overcoming the resultant friction. This allows the bullet to build a little inertia before engaging the rifling. What that means is that there is a slight pressure drop until the propellant gases push the bullet into and engage the rifling where pressure goes up. The bullet jumps a gap on firing of the cartridge before engaging the lands of the rifling. A variety of special purpose ammo from ball, armor piercing to blanks are fired from these weapons. Military weapons must accommodate different bullets, generally tracers are longer than the standard ball ammo in the smaller caliber. Both NATO rounds are designed with some free bore. In most civilian commercial designs, the bullet is in very close proximity to the rifling with little free bore. ![]() Free bore is the distance between the ogive of the bullet and where the rifling starts. 308 Winchester, and though they share cartridge dimensions they are not necessarily the same.įirst there is the concept of the chamber design and part of that specification is free bore. 223 Remington while the civilian form of the 7.62 x 51mm is the. Sig Sauer beat out Glock Inc., FN America and Beretta USA in the 17-month competition to replace the Cold-War era, Beretta M9 pistol.The two primary calibers for small arms that are NATO standards are the 5.56 x 45mm and the 7.62 x 51mm and they have their civilian equivalents. The company recently announced it has delivered 100,000 MHS pistols under the 10-year Army contract, which is worth up to $580 million. Army for the Modular Handgun System (MHS), we've seen significant civilian interest to own both variants of the handguns," said Tom Taylor, chief marketing officer and executive vice president for commercial sales at Sig. "Since the official selection of the M17 and M18 by the U.S. The slide is optic-ready when the rear sight assembly is removed. The pistol features a SIGLITE front night sight and a removable night sight rear plate. It comes with one 17-round magazine and two 21-round magazines. The P320-M18 is configured nearly identically to the military models and features black manual safety and other controls, a carry-length coyote-tan grip module and a coyote PVD-finished slide, the release states. The Marine Corps plans to buy 35,000 MHS pistols, which will make the M18 the official sidearm of the Corps, according to the Sig Sauer release. The Air Force is scheduled to purchase 130,000 M18s, and the Navy plans on buying 60,000 of them. The Army plans to buy 195,000 MHS pistols, the majority of which will be M17s, but the rest of the services so far prefer the M18. ![]()
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