Yes, I'm sure Stoner created the "GI proof" rifle in the hopes that soldiers would be kicking back, contemplating the nuances of the mechanics of its operation for decades to come.
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One thing to check- Shoot your AR in the dark, if flames shoot out of the ejection port the spent case is being pulled out of the chamber while the bullet is still in the barrel and high pressure gases are exiting the chamber meaning the pressure is still high in the chamber, the case has not contracted from the chamber walls and at some point the extractor will fail due to excess stress from ripping the case out of the chamber. It doesn't matter if the rifle is a DI or piston either can be over-gassed. If the carrier is moving while the bullet is in the bore it can effect accuracy.
No he designed the gun and it's issued to GIs. Most people issued a gun have very little understanding of it's operation and why it does what it does.
If you're here to debate and discuss the design by all means do. If you're here to be an ass your stay will be very short...last warning.
My entire reason for starting this thread was to ask the question, how do dedicated piston uppers deal with unlocking the bolt and extraction.
To my knowledge they just rip the bolt/shell out by brute force, where as a D.I. gun uses gas pressure to ease the unlocking of the bolt and provide dwell time to allow the case to cool for proper extraction.
What do piston systems like the HK416 employ to facilitate unlocking and extraction.
Has nothing to do with D.I. vs. Piston... this is a technical question
Both systems operate the same way, ie something is exerting force on the carrier. In a DI it's the gas, in the op-rod design it's the op-rod. Unlocking happens when the bolt carrier starts moving to the rear, and the cam pin follows the cam track in the carrier, thus rotating the bolt so that the lugs on the bolt does not align with the lugs in the barrel extention.
There is no forward movement of the bolt in either system.
Both systems incur wear on bolt lugs.
In my 4 years with the HK416 in service, I have not seen a single broken bolt lug.....
There were some issues with the initial 416's, with reports of bolt lug breakage after only 5000 rounds. That happened because HK used a dfferent metal and hardening process on the bolt. They switched back to the original process and metal, and now the bolts last a lot longer.
Well said Grant.
The M16Fow is certainly not GI proof. The system takes some knowledge to keep it running, thats why people who know the system will never have issues and the ones that dont will.
Some people think dry lubes are best for the M16 but if you know the system you will know it needs a good lube to run well.
Like Grant said, the M16 like the 1911 requires knowledge of the system to keep it running, and if you have that knowledge it will never give you troubles.
There is no way the expansion chamber will pressurize enough to start moving the carrier before the bullet can travel from gas port to muzzle. The distance from gas port to muzzle is shorter than it is from gas port to carrier. Also, if I remember correctly, the velocity of the supersonic gases drop to subsonic after passing through the gas port. In the race between bullet to muzzle and gas to expansion chamber, the bullet wins every time.
When you see flames coming out of the chamber, it's for the same reason you see flames coming out of the muzzle. It's the spent gases igniting as they mix with the oxygen in the atmosphere
The so called "piston" uppers actually work the same way as the Stoner system. Both use a piston and cylinder to turn the energy of the expanding gases into mechanical energy. The difference between the two systems is that the Stoner system eliminates the actuator rod and places the piston inline with the bolt & bore. The Stoner system may have a "softer" extraction as it's expansion chamber (cylinder) has a larger volume. In either case, the bullet has long left the bore before the reciprocating mass has a chance to start moving
The bolt does not begin unlocking as soon as the carrier begins moving. The groove in the carrier which engages the bolt cam is straight for a short distance, then angles which delays the unlocking of the bolt
Arctic, your a bit off.
Don't blame your armorer.. they are constrained by the limit of education & most are lego assembling monkeys.
Look at where the piston is in the standard AR. In the middle of the bolt carrier. As gas goes through the key, into the chamber (within the carrier) it pushes in all directions.
- The bolt will be pushed forward and the carrier rearward... gas venting out the side holes in the carrier as the gas rings pass.
- as the carrier is pushed rearward the cam path unlocks the bolt, aligns it with openings in barrel extension
- momentum is keeping the carrier moving rearward.
The difference was very clear with early hk416's which dug chunks out of the inlet, for the cam pin, in the upper receiver.
BTW the 416 can more correctly be referred to as a gas tappet, not oprod. Ala the G36 some of your countrymen use
There will be forces pushing forward against the piston/bolt, but not great enough to cause the bolt to move within the barrel extension.
1- The resistance to pushing the bolt forward is much greater than the resistance to moving the carrier rearward.
2- A round in the chamber usually fits snugly enough to take up any slack there may be between the bolt and barrel extension, even before firing.
3- The expanded case will keep the pressure in the expansion chamber from moving the bolt forward. During firing, the case is pushed rearward against the bolt face and expands to stick to the chamber walls. The case should have shrunk by the time the gases enter the expansion chamber, but the case has expanded to fill the chamber. The only way the bolt can be moved forward is to crush the brass.
4- While the pressure in the entire system is dropping because the bullet has uncorked it, pressure in the carrier is still less than the pressure in the chamber and bore.
The gases in the expansion chamber cannot move the bolt forward in the barrel extension