"SlamFire / CookOff" Definition Question,
R.M.R.
phenomenon.thanks
Ray,
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Dr JP Hrisoulas
In answer:
A "Cook off" comes from a live round being chambered in a waaay too hot barrel.
The rounds gets heated to the point where it simply "cooks off" from the heat.
I have een it happen to others (mostly these are rapid fire AR or AK-ites that
think that pulling the trigger as fast as you can is good shooting and running
through 3 opr 4 mags full as fast as they can be changed is the way to go...)
but never happened to me..This is something that can be very hazardous as the
weapon can discharge at any time, no matter if the safety is engaged or not.
A Slam Fire, oh those can be downright deadly.(.to the shooter) if the firearm
fires out of battery (before the breech end locks shut). Think of an open bolt
gun that wasn't designed to fire as an open bolt gun and you'll get the
picture.
Just about any gun has the potential to slam fire when the action is closed,
even bolt action rifles and some top breaking revolvers (albeit this would mean
a major parts problem on either one but it could happen, as rare as it would be
for it to actually occur). Some firearms designs are more "prone" to it than
others. The Garand/M1A, if not kept well maintained has had a bit of a history
on this. Improper assembly of a SKS can also cause slam fires. All a slam fire
is, well it's the round being touched off when the action is in the act of
closing. It may or may not be in battery (locked closed)...and of it is NOT,
well you can blow up the gun, loose a finger or a hand, and maybe much more.
Usually slam fires are caused by a "stuck" firing pin that is protruding from
the bolt face. Sometimes it is a combination of inertia and very sensitive
primers (this last cause is the most common slam fire, as far as I can tell, in
the Garand/M1A).
Now do not confuse a slam fire with open bolt opperation, as these weapons were
designed for that mode of loading/firing.
Anyway, I hope this helps..
JPH
Dr JP Hrisoulas
Metallographer, Lecturer
Author: The Complete Bladesmith
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Chris Johnson
chambered for any of a number of reasons, which may include debris stuck
to the bolt face which can act as a firing pin, or a firing pin that slams
forward into the primer on chambering though it isn't driven by the hammer,
or a mechanical malfunction that allows the hammer to strike the firing
pin before it's supposed to.
AR-15/M16 type rifles are at a SLIGHT risk of slamfiring due to the
design of the firing pin system, which does not use a spring to hold
the pin away from the bolt face. If the gun is over-lubricated
and the ammo has unusually soft primers, slamfires may and occasionally
have occurred. If you chamber a round in an AR-15 and then extract
it before firing it, you may notice a very small dent in the primer from
the firing pin striking it when the bolt is closed.
A cookoff is what happens when a round is chambered in a gun that
has been fired a lot VERY recently, heating the chamber up to the
point where the round gets hot enough to go off without pulling
the trigger. The round cooks in the hot chamber, and if it gets
hot enough, BANG.
CJ
"R.M.R." wrote:
> ...
Jerry Kendrick
A slamfire occurs when the cartridge is unintentionally discharged as a
result of the bolt "slamming" into the cartridge case and detonating the
primer. I suppose likely culprits would be a firing pin spring too weak
that allowed the firing pin to go forward with sufficient force to detonate
the primer, or even possibly a metal shaving stuck on the face of the bolt.
Many modern firearms (particularly pistols) have firing pin locks that would
preclude the runaway firing pin theory. I've done quite a bit of shooting
and been around more, and have only seen this occur with a .22 rimfire
rifle. I'm sure others may report more instances, but I'd have to say it
was pretty rare.
A "cookoff" occurs when the chamber temperature is hot enough to ignite
the powder in the cartridge without benefit of detonating the primer. This
would be most common in machine guns, I'd suspect. I know they mentioned
this possibility in the Army when I went through basic. With most sporting
arms I'd say this condition was very rare.
Hope it helped.
Jerry Kendrick
"R.M.R." <Par...@webtv.net> wrote in message
news:a508k3$bm1$1...@xring.cs.umd.edu...
> ...
Wandering John
from the forward movement of the bolt - this is often the case when an
unfixed firing pin is stuck forward.
A Cookoff occurs when the firearm, particularly the barrel, is sufficiently
hot to ignite a chambered round (or god-forbid, unchambered round),
without the mechanical ignition from a firing pin. Often, this is not
immediate
to chambering a round.
Commonality :
Slamfire occur whenever a firing pin is dirty enough.
On clear, maintenanced firearms - almost never.
On dirty, faulty or neglected firearms - they can occur
period.
Cookoffs occur if the user neglects the firearm and continues
to fire without cooling or changing the barrel. It should be
warned that, before a cookoff, you run the risk of having a
projectile become lodged in an overheated barrel due to expansion.
"R.M.R." <Par...@webtv.net> wrote in message
news:a508k3$bm1$1...@xring.cs.umd.edu...
> ...
Rob Novak
#What are the definitions for slamfire and cookoff and how common is this
#phenomenon.thanks
A slamfire occurs most often when the force of the action closing is
enough to carry the firing pin forward with sufficient inertial energy
to strike the primer and discharge the round. Most often caused by
too-light firing pin return springs or too-heavy recoil springs. Occurs
in ill-maintained or badly modified semi-automatic weapons for the most
part.
A cook-off occurs mostly in fully automatic weapons, where (due to the
high rate of fire) the barrel and chamber get so hot, that the powder in
the cartridge ignites without benefit of a primer strike.
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Rob Novak
#What are the definitions for slamfire and cookoff and how common is this
#phenomenon.thanks
A slamfire occurs most often when the force of the action closing is
enough to carry the firing pin forward with sufficient inertial energy
to strike the primer and discharge the round. Most often caused by
too-light firing pin return springs or too-heavy recoil springs. Occurs
in ill-maintained or badly modified semi-automatic weapons for the most
part.
A cook-off occurs mostly in fully automatic weapons, where (due to the
high rate of fire) the barrel and chamber get so hot, that the powder in
the cartridge ignites without benefit of a primer strike.
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rb...@fuse.net
#What are the definitions for slamfire and cookoff and how common is this
#phenomenon.thanks
#
Slamfire occurs when the slide on a semi auto causes the round being
chambered to discharge. Pretty uncommon, but they occur often enough
that they have a name. Usually caused by a headspace problem on
rimfire guns, broken/jammed firing pins, or excessive dirt that
prevents the firing pin from retracting after the hammer strike.
Cookoffs occur when the barrel/action gets so hot that the primer
fires from the heat, or the powder combusts. Very rare to get a gun
that hot because it burns your hand. Where you see this occur is
when a loaded gun is involved in a fire at a home/car. Individual
rounds can "cookoff" too. For an example, pitch a box of 22s into
a fire sometime, then run. The danger from that is fairly low. The
danger from a gun in a fire is pretty close to that of an intentional
discharge.
Bray Haven
#What are the definitions for slamfire and cookoff and how common is this
#phenomenon.thanks
#
Slamfire is when the closing of the action and not the intentional trigger pull
fires the weapon. Cookoff is when a machine gun barrel get so hot it ignites
the round before the primer is struck. The former is more common.
Greg Sefton
Bruce Markowitz
pulling of the trigger
Garands are notorious for this if there is a problem with the
mechanics
Cookoff is when the heat of the chamber sets off the chambered round -
only happens with machine guns, and then I think only the belt fed
variety can feed fast enough to get that hot. This is why most machine
guns fire from an open bolt - the round is not chambered until the
trigger is pulled
On 20 Feb 2002 08:33:55 -0500, Par...@webtv.net (R.M.R.) wrote:
> ...
FalconsHunt
is a detonation of the primer and attendant firing of the weapon by the
force of the slide or bolt going forward. In the case of a .22, where I
have some experience with it, it can be caused by an improperly machined
bolt face or slide (again my experience) or by an accumulation of dirt
and crud on the boltface or slide. I believe that with a center fire
cartridge the most likely cause would be an improperly seated primer,
although I have never seen this actually happen. In any event, my
experience is that is is pretty uncommon.
A cookoff, as I understand the term, is a cartridge going off at some
reasonably extended period after being struck by the firing pin. Again,
the idea is that the pin hits the primer which for whatever reason
ignites slowly so that it at first appears to be a misfire. Some seconds
later the cartridge will actually fire. This is why they tell you not to
clear a misfired cartridge immediately, but let it sit in the chamber
for awhile. I have heard about cookoff's since I started shooting 40
years ago. I have never seen one and I have never actually talked to
anyone who has seen one.
R.M.R. wrote:
> ...
xlea...@mail.airmail.net
#What are the definitions for slamfire and cookoff and how common is this
#phenomenon.thanks
Slamfire is, by definition, the situation that occurs when the round
is fired when it is chambered without the sear disengaging. It is most
common in semi-autos and autos though it can occur in bolt or lever
action firearms. Common causes are:
1. A firing pin that is stuck or jammed forward causing the firing pin
to strike and ignite the primer as the round is slammed into the
chamber. Auto loading weapons that fire 'from an open chamber' like
the Sten are designed to fire this way, so maybe it's not a slamfire
when they do.
2. Excessive bolt speed causing the firing pin to move forward under
intertia with sufficient force to strike and ignite the primer.
In both cases ignition normally occurs with the round fully chambered
though the action may not have fully locked in battery. The situation
is rare, but can and does occur. See the FAQs at Fulton_Armory.com for
a description of slamfires when am M-16 is fed by hand with the
magazine removed and the bolt is allowed to move forward without
retardation.
Cookoff is luckily very rare in modern firearms (I exclude artillery
and black powder weapons - outside my ken). I have seen it occur only
with full auto firearms fired a continuous rate far higher than their
design criterea. It is the result of DRASTIC overheating of the
chamber. The round absorbs enough heat during the chambering cycle for
the charge or primer to ignite spontaneously. Unlike a slamfire the
primer is not hit by the firing pin. I've heard many arguments over
whether the primer cooks off igniting the charge or the charge cooks
off and ignites the primer - it really doen't matter, the effect is
the same. Depending on the point in the chambering cycle where the
round absorbs enough heat, the round and bolt may be at any point in
the cycle. My crewchief had to break the belt on an M-60 mounted as a
chopper door gun to get it to stop firing. Luckily the rounds were
cooking off while the bolt was locked! The barrel was visibly glowing
in broad daylight. Tracer rounds were visibly 'keyholing' and
spiraling in flight. It was a bit wild when the D^&& thing would not
quit shooting. The barrel and receiver were a total loss andthe bolt
was essentially welded in place once it cooled.
Hope that answers the qx, tho' I'm sure you'll get far more learned
responses.
Regards.
dgr...@cs.csuabk.edu
# What are the definitions for slamfire and cookoff and how common is this
# phenomenon.thanks
Slamfire is when the firing pin on a semi-auto firearm gets stuck forward
somehow, thus causing the firearm to fire full-auto. This is bad because
the gun is not functioning as designed and there's a chance of a round
firing with the bolt not completely closed. If that happens, BOOM! Some
firearms are designed to slamfire on purpose. The old Sten is a good
example. Its firing pin is just a bump carved into the bolt face.
Cookoff is when the chamber gets so hot that a round fires as soon as it's
inserted into the chamber. This is really only a problem for machine
guns.
--
David Griffith
dgr...@cs.csubak.edu
Ranger1002
#phenomenon.thanks
Slamfire is when you release the slide or bolt on a firearm and the round that
is being loaded into the chamber fires when the slide or bolt slams forward.
An example is in AR-15 type rifles. The firing pin is free floating and the
intertia of the bolt going forward could be enough force to fire the round.
Try loading a round into the chamber and then ejecting it and seeing if there
is a light mark on the primer from the firing pin.
Cook off is when the firearm gets so hot from sustained firing that the round
in the fires from its powder igniting from the heat.
TN65X57
firing pin, or no firing pin return spring.
Slam fire is best thought of as the round going off as the slide or bolt is
dropped/closed on a round loaded in the chamber. Though some of the simple
sub-machine guns simply have a fixed firing pin on the bolt and fire everytime
the bolt comes to full battery on a chambered cartridge. A stuck firing pin on
a semi auto or firing pin with enough inertia can also produce a slamfire when
the bolt closes.
Cook-off: See really hot automatic weapon. This typically happens when a
automatic weapon has fired quite a few rounds at a sustained rate of fire and
then a round is chambered. The round goes off as the powder reaches ignition
temperature from the heat of the barrel ratther from the fire from the primer.
LouisB
Just an opinion of course.
Ti Coq
against the barrel with a new cartridge inside. The firing pin, upon
this impact, iginites the primer of the cartridge and expell the
bullet. It happens sometimes with some models. A small amount of SKS
owners, for example, have this problem. I have myself a SKS and a .22
semi-auto and I never had a slam-fire. In most cases, it's because
the firing pin is inert (not linked to a spring).
Cookoff: it happens when the barrel of a automatic firearm is really
too hot. Heat is transmitted to a live cartridge inside the chamber
and the primer ignites upon this unusually high heat. It happens more
frequently than slamfires, but only when the barrel of an auto gun is
too hot after long time auto firing.
If you have related-firearms questions, ask me !
Ti-Coq