M16 v M14 circa 1968

[Bartholomew Roberts]

M16 Rifle Reliability and Quality Assurance Evaluation (422pg 15.0MB PDF)

Basically, this 1968 document investigates the teething issues with the (then) new M16 and M16A1 and compares the performance of the rifle with the M14.

A couple of key points it discovers (keep in mind these are 1968 M16s and M14s - some of the M16s in the test have non-chromed chambers and the older buffer. They are also switching back and forth between ball and IMR propellant):

Magazines, Ammunition and Environment are the three biggest factors in reliability of either rifle.

The M16 dominates the rain forest environment; but fares poorly in the swamp and beach environment. The M14 dominates the swamp and beach environment and is worst in the rain forest environment.

Neither rifle likes sand in its working parts.

Cyclic time (vs. cyclic rate) is a major issue in M16 function and affects the likelihood of either rifle to function reliably.

If you change the buffer on the M16 to be more reliable in full-auto, you see more failures in semi-auto and vice versa.

The M16 is more reliable than the M14 initially; but once the M16 starts having stoppages, they come faster and faster while the M14 remains steady.

Chrome chamber M16s resist humidity and corrosion better; but actually have a higher number of malfunctions than non-chrome chamber M16s. On the other hand non-chrome chamber M16s have a higher incidence of bent rims, suggesting that their function is right on the edge and also suffer more pitting and earlier failures from lack of cleaning. It is hard to get any real feel for how much chrome contributes to the problem (or doesn't) since they also mixed in different buffers, different ammo propellants, and different environments in the testing.

Four different tests report Mean Rounds Before Stoppage (MRBS) of the M16 as 1,922 MRBS (function firing during acceptance), 3,040 MRBS (30,000rd. endurance test conducted by Colt), 2,298 MRBS (field test conducted at Ft. Polk), 512 MRBS (field test conducted in Panama with issue weapons and no cleaning - mix of chromed and non-chromed chambers, this is for ball powder only). 296 MRBS (field test conducted in Panama with issue weapons and no cleaning - mix of chromed and non-chromed chambers, this is for IMR powder only).

M16 is held to a much more stringent accuracy standard than the M14.

 

[Chipperman]

422 pages! Whew...

Thanks for the summary.

I'll save the reading for a rainy day.

 

[Bartholomew Roberts]

O, I forgot to add - on both rifles the majority of failures occurred within the first two rounds out of the magazine. The study attributes this to a cycle time that is faster than the magazine can push a fully loaded mag into position (possibly this is the birth of the 18 rounds in a 20rd magazine practice?)

Also 78% of the failures for the M16 from the Panama field test are attributed to improper (i.e. none) cleaning.

 

[GRIZ22]

I used both M14 and M16 in Vietnam and never had any real problems with either. I maintained them the way I was trained to. There are 2 reasons I learned for the 18 in the 20 rd mag one of which is still applicable to 28 in a 30. Original M16 mags were made of an alloy which would spread the lips of the mag if it were fully loaded. They wouldn't spread with 18 as the pressure on the lips was less. The other reason was if you needed to do a tactical reload (you've fired 7-8 shots and want your weapon fully loaded to move, assault a position etc). Try putting a fully loaded 20 or 30 round mag in an AR with the bolt forward. It usually will not lock up and if it does it requires a lot of force. You can do it with 19 or 29 but 18 or 28 just make it easier.