We've come a long way since the flintlock sent the Brown Bess back on the boats it came in on. There are a lot of things that are state of the art for the combat long arm today. The longer term trend is for light weight, simple construction, and having the controls to safely operate the weapon quickly.
More than piston vs. direct impingement, which I'll summarize first. In pure engineering terms, DI is better. Complain about the application all you want, what you get with direct impingement is gas directed to the piston on the back of the bolt head, contained in the gas chamber as part of the bolt carrier. Direct impingement means no operating rod - not, no piston at all. It saves a lot of weight, and has less surfaces to be machined, or wear out. The thrust is axial, straight in line with the action, not offset, and even compensates for bolt thrust with an opposing force against it. The exiting gas is directed out of the bolt carrier through the ejection port, not under the handguards, and once the case begins extraction, any residual gas in the barrel comes past the case, just like a piston gun. (Only manually operated bolts have clean faces and shiny brass extracted.) No one is required to like one action over the other, but if you look at it for what it really does, DI is lighter weight and less complicated.
What a lot of folks also miss is that modern rifles use barrel extensions that lock the bolt up, not the receiver. This also cuts down weight and machine costs, allowing much easier fabrications to hold the parts in place against the abuse of the human user, not 50,000 pounds of chamber pressure. Thats why extruded aluminum uppers and cast resin lowers are now possible. The same technology that makes the $5 pocket knife is being applied to firearms.
How the user holds and controls the weapon is also much better. The current trend is to use the trigger hand on a pistol grip to hold the weapon against the shoulder. The off hand holds the barrel up. Since the trigger hand is stationary, it should have the trigger, safety, and mag release at finger tip reach. The off hand can be reaching for a mag, loading it in the empty well, and bumping the bolt hold back while the finger is on the trigger, safety on or off as the circumstances need. The user is in back in the fight much sooner without loss of sight picture.
If there is a stoppage, cycling the bolt with the off hand by a bolt operating stud or handle is preferable, especially one located where the user does not have to break cheek weld. This clears the action, allows a mag change, and keeps the target in the sight picture. Whether enemy soldier or just the shot of the season, the user again gets back into the shot sooner, rather than too late.
The adoption of the picitinny rail for sights makes adding optics much easier, and creates a standard mount where only individual custom sets were offered. Having a universal mount doesn't necessarily make them more efficient or lighter weight, but it does solve a lot of problems with having to buy specialized parts that have only one application. In a team, optics can be shared, swapped, or interchanged based on mission or state of maintenance. It also makes weapons more interchangeable between shooters, with less compensation. If everyone shoots with there nose touching the back of the upper, there is less variation in sight picture. In the heat of close combat, picking up any weapon that can shoot close to point of aim is better.
Adjustable length of pull for the armored soldier offers a consistent cheek weld, too, and allows for variations necessary when fitting to our inconsistent human anatomy. Stature or gender based differences no longer hamper operation, and the user has a better fit to shoot more accurately.
A magazine designed to hold and feed ammunition in a reliable and durable manner is also important, and when done properly, contributes a significant amount of reliability, if not even compensating for other inferior qualities of the weapon. The magazine should have feed lips that cannot be bent if dropped loaded on them, have a continuous shape related to the stacking of ammo in it, and be constructed of materials that cannot be deformed or damaged in combat use. There should be no compromises to accommodate deviations from those standards simply because of institutional or political tradition.
Modern weapons need modern maintenance, which includes the use of dry film lubricants, ion or nitride coatings, and modern methods of construction for barrels and parts. If a military standard was created, it superceded a previous one, and that's what should be done as an ongoing process, continually incorporating newer processes, rather than ignoring them and creating an even larger burden later to accept them. We should not cling to outdated and demonstrably inferior ways of making parts simply because the standard was written decades ago and hasn't been reviewed since.
When we see what is issued as a combat rifle twenty years from now ( or hopefully sooner with the Improved Carbine,) we'll see much of this incorporated as standard. While one or more items may not make the final configuration, most will, and in the long run, they all will be present. It's simply that each is superior in combat use, and has already made the list of what is included in a weapon. They should ALL be considered a minimum without compromise, but the reality is that we always try to get most of them, and the result is usually another step forward in efficiency on the battlefield.
More than piston vs. direct impingement, which I'll summarize first. In pure engineering terms, DI is better. Complain about the application all you want, what you get with direct impingement is gas directed to the piston on the back of the bolt head, contained in the gas chamber as part of the bolt carrier. Direct impingement means no operating rod - not, no piston at all. It saves a lot of weight, and has less surfaces to be machined, or wear out. The thrust is axial, straight in line with the action, not offset, and even compensates for bolt thrust with an opposing force against it. The exiting gas is directed out of the bolt carrier through the ejection port, not under the handguards, and once the case begins extraction, any residual gas in the barrel comes past the case, just like a piston gun. (Only manually operated bolts have clean faces and shiny brass extracted.) No one is required to like one action over the other, but if you look at it for what it really does, DI is lighter weight and less complicated.
What a lot of folks also miss is that modern rifles use barrel extensions that lock the bolt up, not the receiver. This also cuts down weight and machine costs, allowing much easier fabrications to hold the parts in place against the abuse of the human user, not 50,000 pounds of chamber pressure. Thats why extruded aluminum uppers and cast resin lowers are now possible. The same technology that makes the $5 pocket knife is being applied to firearms.
How the user holds and controls the weapon is also much better. The current trend is to use the trigger hand on a pistol grip to hold the weapon against the shoulder. The off hand holds the barrel up. Since the trigger hand is stationary, it should have the trigger, safety, and mag release at finger tip reach. The off hand can be reaching for a mag, loading it in the empty well, and bumping the bolt hold back while the finger is on the trigger, safety on or off as the circumstances need. The user is in back in the fight much sooner without loss of sight picture.
If there is a stoppage, cycling the bolt with the off hand by a bolt operating stud or handle is preferable, especially one located where the user does not have to break cheek weld. This clears the action, allows a mag change, and keeps the target in the sight picture. Whether enemy soldier or just the shot of the season, the user again gets back into the shot sooner, rather than too late.
The adoption of the picitinny rail for sights makes adding optics much easier, and creates a standard mount where only individual custom sets were offered. Having a universal mount doesn't necessarily make them more efficient or lighter weight, but it does solve a lot of problems with having to buy specialized parts that have only one application. In a team, optics can be shared, swapped, or interchanged based on mission or state of maintenance. It also makes weapons more interchangeable between shooters, with less compensation. If everyone shoots with there nose touching the back of the upper, there is less variation in sight picture. In the heat of close combat, picking up any weapon that can shoot close to point of aim is better.
Adjustable length of pull for the armored soldier offers a consistent cheek weld, too, and allows for variations necessary when fitting to our inconsistent human anatomy. Stature or gender based differences no longer hamper operation, and the user has a better fit to shoot more accurately.
A magazine designed to hold and feed ammunition in a reliable and durable manner is also important, and when done properly, contributes a significant amount of reliability, if not even compensating for other inferior qualities of the weapon. The magazine should have feed lips that cannot be bent if dropped loaded on them, have a continuous shape related to the stacking of ammo in it, and be constructed of materials that cannot be deformed or damaged in combat use. There should be no compromises to accommodate deviations from those standards simply because of institutional or political tradition.
Modern weapons need modern maintenance, which includes the use of dry film lubricants, ion or nitride coatings, and modern methods of construction for barrels and parts. If a military standard was created, it superceded a previous one, and that's what should be done as an ongoing process, continually incorporating newer processes, rather than ignoring them and creating an even larger burden later to accept them. We should not cling to outdated and demonstrably inferior ways of making parts simply because the standard was written decades ago and hasn't been reviewed since.
When we see what is issued as a combat rifle twenty years from now ( or hopefully sooner with the Improved Carbine,) we'll see much of this incorporated as standard. While one or more items may not make the final configuration, most will, and in the long run, they all will be present. It's simply that each is superior in combat use, and has already made the list of what is included in a weapon. They should ALL be considered a minimum without compromise, but the reality is that we always try to get most of them, and the result is usually another step forward in efficiency on the battlefield.
