This article was submitted by CBA member, Steve Hurst.
Shooting Cast Bullets in Semi-Auto Pistols Starting loads in manuals for semi-auto cartridges are often set at levels which will provide function in a pistol with a standard spring. The most accurate cast bullet load is often below the recommended starting load, especially in high pressure cartridges. Accurate cast bullet loads may not function the pistol with a standard spring. In this case a lighter spring is required to get reliable function.The recoil spring is a vital part of the functioning of any semi-automatic pistol. Factory springs are a compromise, weighted heavily toward reliability. The factory weight spring is intended to provide reliable function with standard factory loads under all reasonable conditions. With a pistol which is always clean and well lubricated, it may be possible to use a heavier spring with standard loads. Extra power loads, high velocity or heavy cast bullet loads generate higher slide velocity. Use of a standard spring with heavy loads puts increased stress on the pistol. This can crack the frame or slide and will cause general excessive wear. It also makes the pistol more uncomfortable to shoot. For heavy loads an appropriate spring weight is required. The following are weights of some Wolff springs for Colt 1911 type semi-automatic pistols. These weights are not meant to indicate the normal weights of these springs, the weights of identical poundage springs may differ slightly. However, because spring alloys have very similar density and poundage is related to the amount of metal in compression, these weights can be an approximate indicator of poundage of unknown springs for 1911 pistols. Recording the weights of recoil springs is a good method of keeping track of the identity and poundage of springs. Springs will not change weight significantly in use unless there is abnormal abrasion. In this case the source of the abrasion should be eliminated.
Wolff Variable:
10 Pound, 97.8 Grains
11 Pound, 106.1 Grains
12 Pound, 107.7 Grains
14 Pound, 113.4 Grains
16.5 Pound, 125.7 Grains Factory Standard 45 ACP
17.5 Pound 129.8 Grains
18.5 Pound, 134.4 Grains
20 Pound, 136.7 Grains
22 Pound, 141.3 Grains
Wolff Conventional:
11 Pound, 106.8 Grains
12 Pound, 107.8 Grains
13 Pound, 111.3 Grains
14 Pound, 112.1 Grains
15 Pound, 123.7 Grains
Shooting Cast Bullets in Semi-Auto Pistols Starting loads in manuals for semi-auto cartridges are often set at levels which will provide function in a pistol with a standard spring. The most accurate cast bullet load is often below the recommended starting load, especially in high pressure cartridges. Accurate cast bullet loads may not function the pistol with a standard spring. In this case a lighter spring is required to get reliable function.The recoil spring is a vital part of the functioning of any semi-automatic pistol. Factory springs are a compromise, weighted heavily toward reliability. The factory weight spring is intended to provide reliable function with standard factory loads under all reasonable conditions. With a pistol which is always clean and well lubricated, it may be possible to use a heavier spring with standard loads. Extra power loads, high velocity or heavy cast bullet loads generate higher slide velocity. Use of a standard spring with heavy loads puts increased stress on the pistol. This can crack the frame or slide and will cause general excessive wear. It also makes the pistol more uncomfortable to shoot. For heavy loads an appropriate spring weight is required. The following are weights of some Wolff springs for Colt 1911 type semi-automatic pistols. These weights are not meant to indicate the normal weights of these springs, the weights of identical poundage springs may differ slightly. However, because spring alloys have very similar density and poundage is related to the amount of metal in compression, these weights can be an approximate indicator of poundage of unknown springs for 1911 pistols. Recording the weights of recoil springs is a good method of keeping track of the identity and poundage of springs. Springs will not change weight significantly in use unless there is abnormal abrasion. In this case the source of the abrasion should be eliminated.
Wolff Variable:
10 Pound, 97.8 Grains
11 Pound, 106.1 Grains
12 Pound, 107.7 Grains
14 Pound, 113.4 Grains
16.5 Pound, 125.7 Grains Factory Standard 45 ACP
17.5 Pound 129.8 Grains
18.5 Pound, 134.4 Grains
20 Pound, 136.7 Grains
22 Pound, 141.3 Grains
Wolff Conventional:
11 Pound, 106.8 Grains
12 Pound, 107.8 Grains
13 Pound, 111.3 Grains
14 Pound, 112.1 Grains
15 Pound, 123.7 Grains
Variable power springs have less force when the slide is forward and more force when the slide is fully rearward. This is achieved by varying the coil spacing. The difference is small and I use variable power springs for all purposes. It has been widely recommended to cut “XX” coils off a standard spring to make a target load spring. This is poor practice, it causes abnormal spring load in the firing cycle. Recoil springs are cheap, it is now possible to purchase new top quality springs of any desired poundage.
Spring Selection:
The following deals with 1911 type pistols, but the procedure is the same for any semi-automatic pistol. Wolfe makes recoil springs for most models. Finding the correct recoil spring is easy.Be sure the pistol is clean and lubricated as it would be in normal service. Have a hundred rounds of the test ammunition available. If you are using hand loads, they must have consistent power level. To check this, chronograph them, the standard deviation of the velocities should be equivalent to factory loads. Hand loads should be all one head stamp and type. Case type affects extractor fit and ejection. Be sure the extractor and ejector are functioning properly. In 1911 pistols, the ejector should be tight and the extractor tension should be correct. The extractor should hold a fired case on the breach face against slight finger pressure. If you are using a buffer, which you should for high power loads, and is advisable for extensive shooting, be sure it is serviceable.If using normal or heavy loads, start with the heaviest spring; if using target loads, start with a normal spring.Fire a round.If the case ejects, fire 20 to check for consistent function. If any case does not eject, go to the next lighter spring. When 20 rounds function, carefully watch the ejection of the fired cases. If any case fails to eject or ejects slowly, go to the next lighter spring.When you get consistent ejection; fire 50 rounds from fully loaded magazines.Feeding from a fully loaded magazine takes the most force.For pistols that eject the cases horizontally, the cases should land 3 to 6 feet from the gun when fired from a standing position. If cases are ejected forward, this usually means weak ejection and the case is being carried forward by the returning slide. When you get consistent function, you have found the correct spring for that load in that pistol.The above will select the correct spring for a gun which is clean and lubricated. This weight spring will minimize gun wear and is what you want for target or sport pistols that will be fired extensively. For a service or carry pistol you want additional safety margin so the pistol will function under adverse conditions. You should select a lighter spring for carry purposes, perhaps the next poundage lighter. If you use a pistol for both target and service loads, both springs should be kept in the box with the pistol and a means of identifying the springs is essential. Clean one spring and spray very lightly with paint, not a coating, just enough so flecks of paint are visible. You do not want paint flaking off in the pistol. Re-oil the spring when the paint is dry Springs lose their tension with use. The greater the stress, the faster the loss, a higher poundage spring loses tension faster. A high quality, normal power ~16 pound spring for a 1911 is good for many thousands of rounds. An extra power spring, for example a 22 pound spring, may only last 500 rounds before needing replacement. When a spring loses tension, your pistol will be absorbing the excess slide energy of each shot. When you first receive a new spring, install the spring in the firearm and cycle the action several times. Some springs will lose length on the first few compressions, this is normal; especially for the higher power springs. After compressing the spring, measure the length of the spring and weigh the spring. Record this length and weight and the number of the pistol the spring is installed in. Keep this record with the pistol. Every time you disassemble the gun for cleaning, examine and measure the spring. A spring which is more than 10 percent shorter than the reference length should be replaced.
Blowback Pistols:
The above procedure can be used to determine the correct spring for any locked-breach pistol. Blowback operated pistols are very different, the cartridge case acts as a piston to impart velocity to the slide. Slide velocity is dependent on chamber pressure and time, with a slight inverse relationship with case/chamber wall friction. This force is quite large, even low pressure rounds like 380 auto exert pressures of several thousand pounds on the slide. No spring of useable power is capable of slowing initial slide opening. Slide inertia alone provides the primary resistance to premature opening.In blowback pistols there is a fine balance between slide mass (inertia) and ammunition power. The window for correct and safe operation is much narrower than a locked breach design. Factory ammunition is loaded with small charges of fast powders. Attempts to increase power with larger charges of modern dense powders causes a longer pressure curve and early opening. Pressure may be normal, but early opening while pressure is high can result in a case rupture. A heavier spring cannot prevent this.
Buffers:
Buffers are plastic wafers which are installed in the pistol and absorb the slide impact with the frame. They save wear on the pistol, but may cause functioning problems. Because they limit slide travel by the thickness of the buffer, ejection and slide lock functions can be affected. Function must be checked in the individual pistol, problems may be eliminated by choosing a different (thinner) brand of buffer. Buffers are available for many popular pistols and some pistols come with from the factory with a buffer. Buffers wear in use and replacement is part of maintenance.
The following deals with 1911 type pistols, but the procedure is the same for any semi-automatic pistol. Wolfe makes recoil springs for most models. Finding the correct recoil spring is easy.Be sure the pistol is clean and lubricated as it would be in normal service. Have a hundred rounds of the test ammunition available. If you are using hand loads, they must have consistent power level. To check this, chronograph them, the standard deviation of the velocities should be equivalent to factory loads. Hand loads should be all one head stamp and type. Case type affects extractor fit and ejection. Be sure the extractor and ejector are functioning properly. In 1911 pistols, the ejector should be tight and the extractor tension should be correct. The extractor should hold a fired case on the breach face against slight finger pressure. If you are using a buffer, which you should for high power loads, and is advisable for extensive shooting, be sure it is serviceable.If using normal or heavy loads, start with the heaviest spring; if using target loads, start with a normal spring.Fire a round.If the case ejects, fire 20 to check for consistent function. If any case does not eject, go to the next lighter spring. When 20 rounds function, carefully watch the ejection of the fired cases. If any case fails to eject or ejects slowly, go to the next lighter spring.When you get consistent ejection; fire 50 rounds from fully loaded magazines.Feeding from a fully loaded magazine takes the most force.For pistols that eject the cases horizontally, the cases should land 3 to 6 feet from the gun when fired from a standing position. If cases are ejected forward, this usually means weak ejection and the case is being carried forward by the returning slide. When you get consistent function, you have found the correct spring for that load in that pistol.The above will select the correct spring for a gun which is clean and lubricated. This weight spring will minimize gun wear and is what you want for target or sport pistols that will be fired extensively. For a service or carry pistol you want additional safety margin so the pistol will function under adverse conditions. You should select a lighter spring for carry purposes, perhaps the next poundage lighter. If you use a pistol for both target and service loads, both springs should be kept in the box with the pistol and a means of identifying the springs is essential. Clean one spring and spray very lightly with paint, not a coating, just enough so flecks of paint are visible. You do not want paint flaking off in the pistol. Re-oil the spring when the paint is dry Springs lose their tension with use. The greater the stress, the faster the loss, a higher poundage spring loses tension faster. A high quality, normal power ~16 pound spring for a 1911 is good for many thousands of rounds. An extra power spring, for example a 22 pound spring, may only last 500 rounds before needing replacement. When a spring loses tension, your pistol will be absorbing the excess slide energy of each shot. When you first receive a new spring, install the spring in the firearm and cycle the action several times. Some springs will lose length on the first few compressions, this is normal; especially for the higher power springs. After compressing the spring, measure the length of the spring and weigh the spring. Record this length and weight and the number of the pistol the spring is installed in. Keep this record with the pistol. Every time you disassemble the gun for cleaning, examine and measure the spring. A spring which is more than 10 percent shorter than the reference length should be replaced.
Blowback Pistols:
The above procedure can be used to determine the correct spring for any locked-breach pistol. Blowback operated pistols are very different, the cartridge case acts as a piston to impart velocity to the slide. Slide velocity is dependent on chamber pressure and time, with a slight inverse relationship with case/chamber wall friction. This force is quite large, even low pressure rounds like 380 auto exert pressures of several thousand pounds on the slide. No spring of useable power is capable of slowing initial slide opening. Slide inertia alone provides the primary resistance to premature opening.In blowback pistols there is a fine balance between slide mass (inertia) and ammunition power. The window for correct and safe operation is much narrower than a locked breach design. Factory ammunition is loaded with small charges of fast powders. Attempts to increase power with larger charges of modern dense powders causes a longer pressure curve and early opening. Pressure may be normal, but early opening while pressure is high can result in a case rupture. A heavier spring cannot prevent this.
Buffers:
Buffers are plastic wafers which are installed in the pistol and absorb the slide impact with the frame. They save wear on the pistol, but may cause functioning problems. Because they limit slide travel by the thickness of the buffer, ejection and slide lock functions can be affected. Function must be checked in the individual pistol, problems may be eliminated by choosing a different (thinner) brand of buffer. Buffers are available for many popular pistols and some pistols come with from the factory with a buffer. Buffers wear in use and replacement is part of maintenance.