DO NOT exchange or switch bolt assemblies from one M16/M16A1 to another. It could cause damage to both you and the rifle.

I've switched bolt assemblies in my AR's several times. (I've had a couple break on me and I replaced them with spares) I thought they were interchangable. WTF is this?

Firing 140 rounds, rapidly and continously will raise the temperature of the barrel to the COOKOFF POINT. At this temperature, any live round remaining in the chamber for any reason may cook off (detonate) in as short a period as 10 seconds. If the cookoff point (or temperature) is felt possible, weapon should be immedately cleared and allowed to cool. Sustained rate of fire for the M16/M16A1 Rifle is 12-15 rounds per minute. This is the actual rate of fire that the weapon can continue to deliver for an indefinate lenght of time without serisous overheating.

I don't think I've ever fired an AR that slowly.

Where is the Army coming from with this info?

probably from testing


edit: remember that is SUSTAINED fire, as in you can keep shooting at that rate till the end of time without overheating the thing

edit 2: and for the bolt thing, yes you can usually swap them however you should not do this without checking headspace

Putting a bolt that has been well used in a different rifle can have some head space issues.The 12-15 rounds per minute thing.I have no idea.I never shot that slowly either.

Quoted: Where is the Army coming from with this info?

From extensive testing and experience.....

Quoted: Quoted: Where is the Army coming from with this info? From extensive testing and experience.....

Not that in a position to argue with the Army, but 12-15 rounds per minute is VERY conservative. I understand where they are coming from (they said indefinately, after all) but for heaven's sake, there are hundreds of thousands of us who have observed diffferently.

+1 on sustained.  I just finished reading the browning 1919 field manual from back in 1940 and it has an ungodly low number for sustained rate of fire as well.

The Army and the rest of the Military for that matter, when you see a warning like "Always check headspace", it means some poor bastard didn't follow directions and paid dearly for his mistake.

Keep in mind, they are trying to prevent guys from pulling the bolt out of a 10k rd old M16 and installing it in another 20k rd M16, without checking headspace or even inspecting the lugs. Military M16's see a LOT more wear and tear than any semi-auto AR.

The Army manual is written that way to keep people who don't know what they're doing from trying to mess around with their weapons.  The KISS principle has to be factored in as well, it does simplify training when all you have to teach is basic marksmanship and routine maintenance.  Most average soldiers (particularly those who are not a combat MOS) probably don't know what headspace is, let alone how to check or adjust it.  

Another admonition that makes sense is that you are not supposed to mess with the trigger group in a M16A2, people have reassembled 3-round burst trigger components incorrectly before and ended up with a runaway gun.  

The Army's opinion is that any weapon maintenance beyond regular cleaning should be left to armorers.  Those sustained fire rates are deliberately set low to provide a margin of safety to the soldier and to increase weapon system life.  

In short, the Army writes things the way they do because they have to worry about Murphy, in addition to concerns about Joe trying to do things he's not qualified to do.  

There's plenty of people in the military who are issued weapons and aren't "gun people" and therefore only know what they've been told by Uncle Sam.  For that matter, there are a good portion of people in the military who are not warriors and/or are not in a combat MOS, I'm sure a lot of the guys here know what I'm talking about.  

Oh, and IIRC, the M16A1 uses a lighter bolt/bolt carrier than the M16A2 and later variants, but I may be wrong.  

Quoted: The Army manual is written that way to keep people who don't know what they're doing from trying to mess around with their weapons.  The KISS principle has to be factored in as well, it does simplify training when all you have to teach is basic marksmanship and routine maintenance.  Most average soldiers (particularly those who are not a combat MOS) probably don't know what headspace is, let alone how to check or adjust it.   Another admonition that makes sense is that you are not supposed to mess with the trigger group in a M16A2, people have reassembled 3-round burst trigger components incorrectly before and ended up with a runaway gun.   The Army's opinion is that any weapon maintenance beyond regular cleaning should be left to armorers.  Those sustained fire rates are deliberately set low to provide a margin of safety to the soldier and to increase weapon system life.   In short, the Army writes things the way they do because they have to worry about Murphy, in addition to concerns about Joe trying to do things he's not qualified to do.   There's plenty of people in the military who are issued weapons and aren't "gun people" and therefore only know what they've been told by Uncle Sam.  For that matter, there are a good portion of people in the military who are not warriors and/or are not in a combat MOS, I'm sure a lot of the guys here know what I'm talking about.   Oh, and IIRC, the M16A1 uses a lighter bolt/bolt carrier than the M16A2 and later variants, but I may be wrong.

Yep,what he said! I got out of 76Y just because of stupid troopers doing some crazy BS.(troop came to me with an M-60 MG that could shoot around corners,seems he put it on the ground,and then ran over it with an M-35),that,and troopers jamming the bolt carriers in the upper reciever!

Quoted: The Army and the rest of the Military for that matter, when you see a warning like "Always check headspace", it means some poor bastard didn't follow directions and paid dearly for his mistake.

+1
The Military says those warnings, cautions and notes are "written in blood".

Quoted: DO NOT exchange or switch bolt assemblies from one M16/M16A1 to another. It could cause damage to both you and the rifle. I've switched bolt assemblies in my AR's several times. (I've had a couple break on me and I replaced them with spares) I thought they were interchangable. WTF is this?

I take it you don't read the "other" forums on the board then, like troubleshooting and build it yourself.

I carry spare bolts and a spare carrier.
All of my spare bolts have been headspace checked and can cross over to any of my AR15's.
You do own a field headspace gauge, right?

I believe you can switch any new bolts and new barrels around as much as you want (as long as they are built to proper specs). But after you fire the gun, they want you to keep the bolt with the barrel because the two pieces get mated to one another after they wear-in. Theoretically, Using a bolt and barrel that isn't worn together may cause an improper head space condition or improper functioning. Theoretically, the M16 doesn't need to be checked for head space when assembling from new in-spec parts. But it's always wise to check it just as a sanity check in case the parts you are using are out of spec or badly worn.

Regarding the rate of fire for an M16, it goes something like this concept (numbers are approx because I don't feel like looking them up):


First minute: 90 rounds
second minute: 45 rounds
third minute: 25 rounds
fourth minute and beyond: 14 rounds per minute


Basically, for the first 3 minutes you can lay down some pretty serious fire without overheating the weapon. But if you want to keep shooting continuosly for numerous minutes/hours, you need to keep it at about 14 rounds per minute or risk overheating and damaging the weapon.

Quoted: I believe

Dead-assed wrong.

What ever it reads, know full well that the guys at the Armorer's that wrote this manual probably forgot more about the AR platform than most of us will ever know.  Uncle Sam burns a shit pile of powder.

Sustained Fire Definition:  (DOD, NATO) Actual rate of fire that a weapon can continue to deliver for an indefinite length of time without seriously overheating.

Here's some notes from the M16 Direct Support Manual. Basically they are saying that a qualified person with the proper tools and gauges can interchange bolts and barrels, but he must check the head space, functioning,  bolt-to-bolt-carrier fit and bolt condition when doing it. They don't want the typical soldier doing it because they know that some conditions exist (mainly using excessively worn or damaged parts) where it could create an unsafe condition if not properly checked.




Bolt assemblies, and/or barrel assemblies may be interchanged , at the Direct Support Maintenance
level, from one rifle to another, under the provisions of the note on page C-3: If these parts are
interchanged the rifle must be checked/inspected as depicted on pages 3-17, 3-21, and 3-33. While
performing these checks and inspections, pay special attention to the headspace requirements on page
3-47.