Blowback Simpson

John Sabato · 02-24-2003, 12:35 PM

Hey Norm,

Blowback simply means an unlocked breech... The Luger uses a toggle mechanism to lock the breech until the recoil causes the upper half to hit the ramps... by the time this happens, breech pressure has dropped to a safe level with appropriate ammo.

The Walther PP and PPK are examples of blowback type actions that have no resistance to the recoil forces and gas pressure except for the friction of the case in the chamber and gun's mainspring or recoil spring... this type of mechanism is normally only used for guns that fire lower powered cartridges like 380 ACP or 32 ACP or 22 LR.

The Astra 400 is an exception to this rule and is a blowback design using the 9mm Luger cartridge... and if you have ever had to jack one into the chamber on an Astra, the strength of the recoil spring on this model 9mm is extraordinary compared to those used on locked breech guns like the Luger, P-38 and Colt Model 1911 designs.

02-24-2003, 12:35 PM	#4
John Sabato Lifer Lifetime Forum Patron Join Date: Jun 2002 Location: The Capital of the Free World Posts: 10,156 Thanks: 3,003 Thanked 2,309 Times in 1,098 Posts	Hey Norm, Blowback simply means an unlocked breech... The Luger uses a toggle mechanism to lock the breech until the recoil causes the upper half to hit the ramps... by the time this happens, breech pressure has dropped to a safe level with appropriate ammo. The Walther PP and PPK are examples of blowback type actions that have no resistance to the recoil forces and gas pressure except for the friction of the case in the chamber and gun's mainspring or recoil spring... this type of mechanism is normally only used for guns that fire lower powered cartridges like 380 ACP or 32 ACP or 22 LR. The Astra 400 is an exception to this rule and is a blowback design using the 9mm Luger cartridge... and if you have ever had to jack one into the chamber on an Astra, the strength of the recoil spring on this model 9mm is extraordinary compared to those used on locked breech guns like the Luger, P-38 and Colt Model 1911 designs. __________________ regards, -John S "...We hold these truths to be self-evident that ALL men are created EQUAL *and are endowed by their Creator* with certain UNALIENABLE* rights, and among these are life, LIBERTY, and the pursuit of happiness..."*