Reliability Improvements M16 - M4A1

[prepare]

Wasn’t the extractor spring upgrade a result of the change in barrel length and gas system from rifle to carbine?

[markm]

Within the parameters of reliability in the cycle of operation it doesn't appear there was much to improve upon the original Stoner design with the gun itself.

Agreed. In fact, skimping on Chrome lining was the decision of MacNamara if I remember correctly. And that's the only TRUE reliability improvement I've read in this thread. The other stuff is nice, but not a reliability improvement.

[prepare]

I also recall an issue with bolts breaking prematurely and Colt actually discovered a flaw in the manufacturing process? So the bolt design was unchanged.

[alx01]

Agreed. In fact, skimping on Chrome lining was the decision of MacNamara if I remember correctly. And that's the only TRUE reliability improvement I've read in this thread. The other stuff is nice, but not a reliability improvement.

This is like saying 1911 is better than Browning Hi-Power. When clearly Browning himself didn't think that was the case since he started working on Hi-Power.


There are a number of issues with the original design. Reliability issues were/are due to both materials and design. Fairly minor ones have been addresses with the official incremental changes listed above (not just chrome lining).

Others issues are inherent to the design and as a result you see significant design changes of HK416 and AR18, and to a lesser degree KAC SR-15 and LMT.
COLT has also made a number of subsequent variants and design improvements, unfortunately non of them were released to the public. I don't remember the exact model numbers, but somebody can chime in with more knowledge on Colt variants including piston and re-designed lower.

[markm]

This is like saying 1911 is better than Browning Hi-Power.

I don't follow the logic. We're not comparing different weapons.

There are a number of issues with the original design.

I would imagine there were issues with the original design, like any new weapon system. But the military fielded M16 really suffered from the jungle environment and lack of chrome in the bore combined with the mis-info on maintenance for the soldiers/marines.

I can't remember ANY other improvements related to reliability. And none of the other points brought up in this thread are reliability improvements for the M16 at all.

[prepare]

This video covers some of the changes.

[MistWolf]

I don't follow the logic. We're not comparing different weapons.



I would imagine there were issues with the original design, like any new weapon system. But the military fielded M16 really suffered from the jungle environment and lack of chrome in the bore combined with the mis-info on maintenance for the soldiers/marines.

I can't remember ANY other improvements related to reliability. And none of the other points brought up in this thread are reliability improvements for the M16 at all.

The improved extractor spring increased reliability.

Improved magazines increased reliability.

Changes to the buffer were made to improve reliability.

[Slater]

Shot peening of the bolt was an early enhancement.

Not a reliability improvement, but Colt proposed the following:

"Upper and Lower Receiver. Shot peen the surfaces to provide a more durable finish and to aid in the prevention of exfoliation and inter-granular corrosion."

I don't think the Army ever approved that one (?).

[lysander]

There are quite a number of changes that improved reliability that people don't know about, or over-look.

There were 145 changes made during the first contract, and 68 further changes made during the second contract.

A large number of these were simple house-keeping, changing the drawing to match the parts as manufactured, or accepting parts that were not quite made to print. However, a good number of them were product improvements, albeit minor ones, like adding a drain hole to the ejector spring passage in the bolt to prevent hydro-locking of the ejector, or changing the gas tube from regular steel to stainless steel.

I don't think a single part escaped modification between the first contract and the acceptance of the drawing package license in 1968.

Shot peening was introduced for a number of parts.

A more interesting question is:

"What changes were made to the M16A1 to make the M16A2 that were improvements to the combat usability of the rifle?"

To discuss changes made to the design to accommodate the M4 configuration is immaterial, as the M4 is a different beast altogether.

[mack7.62]

The early gun powder change actually made the rifle less reliable by jacking up the cyclic rate from about 750 rpm to something like 950 rpm. If I remember correctly, this powder fouled more.

The early lots of Ball Powder not only increased the cyclic rate but it had too much calcium carbonate added I believe to kill flash which led to increased fouling and as the gas tube fouled it raised pressure which caused the rate to go even higher.

But there are two types of early reliability improvements that need to be considered, the mechanical of which being fielded in a tropical environment the chrome lined bore and chamber was one of the most important. Then you have the other little changes that improved not the mechanical reliability but the combat reliability like fencing off the magazine release, closing off the flash suppressor and fielding cleaning kits and supplies.