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From: (Daniel Chisholm)
Newsgroups: rec.guns
Subject: Re: M16 v. M16A2
Date: 31 Mar 1995 23:41:54 -0500
Lines: 49

In article <3ld9cf$>,  <> wrote:
##From my time in the military, the oft quoted wisdom concerning
#the 16A2 was, it could fire either the current M855 (for which
#it was designed) or the older M193. AND the earlier M16 (1 in
#12 twist?) could fire ONLY the M193. My question, WHY?
#what exactly would make a M855 UNSAFE going througthe vanilla
#M-16?  Was this the mothering instinct of some pentagon

Not unsafe.  "ineffective".

The earlier M16s had a twist rate of 1 turn in 12".  The A2s have a much
faster twist rate, 1 turn in 7".   The slow 1 in 12" twist is adequate to
stabilize the 55 grain M193, but will not stabilize the 62 grain M855.
As a result, the newer ammo will group 1-2 FEET at 100 yards, with bullets
flying through the air sideways, instead of shooting to about 2" at 100 yards,
like military ammo should.

The M16A2, with it's faster twist, can accurate fire both the old
and the new ammo. (Purists will argue that there is a minor degradation
in accuracy caused by shooting the old 55 grain M193 through the "too
fast" twist, but this effect is negligible given the purpose of the
ammunition and rifle).

#comittee? Also operator's manuals state that exchange of bolt
#assemblies between rifles might result in injury and/or death
#to personnel ?! If that's the case, why do gun shows have extra
#bolts and asseblies to sell? Any armorers or designers out
#there?  :)

The danger is that the headspace may end up being wrong.  There is
a range of safe, acceptable headspace, but is is possible to end up with
"too short" headspace (which will cause the rifle to be unable to chamber
ammunition), or "too long" headspace which, if severe enough, may cause
the cartridge head to rupture, and release high pressure gas into the
breech.  In severe cases, this may blow up to gun.

Not safety related, but it is also possible that the gas tube may not
align with the bolt carrier.  This will cause unreliable operation.

When a bolt carrier is changed, it is proper top measure the headspace
with a set of GO and NO-GO gauges.  If the rifle will chamber the GO
gauge, it means that headspace is not too small.  If the rifle refuses
to chamber the NO-GO gauge, it means the headspace is not excessive.
Gauges cost about $15 each, and the above operation takes about 1
minute to perform.

- Daniel

Newsgroups: rec.guns
From: (Ed Harris)
Subject: Re: Accuracy and distance of M-14
Keywords: rifle, M14, M16
Date: Mon, 18 Jun 90 19:37:56 GMT

In article <>
(Paul Sullivan) writes:

>    I am looking for information mainly from actual owners of the M-14,
>.308 caliber semi-auto rifle.  What would you say is the distance you
>would could hit (I don't know...something deer-sized) given moderate
>wind.  I have heard from an owner of a AR-15 (.223) that with moderate
>wind the rifle would only hit something inside of 150 yds.  I am wondering
>if the extra weight and power of the .308 caliber if that would affect
>bullet performance that much.

There is quite a bit of difference in the accuracy obtainable by NRA
Master competitors firing on a target range with accurized rifles and
match-grade ammunition than a soldier firing under field conditions.
When we did the operational testing of the M16A2 the weapons were
tested under standard known distance firing, but more importantly, over
the field range course, AFTER having completed the Day Movement Course
and getting to the range after having completed a 20 km, or about 12.5
mile forced march with normal patrol equipment, carrying a full
compliment of radios, MRE's, M249 SAW's, LAW's etc. A platoon of troops
carrying the M16A1 comprised the baseline, and a third platoon of
troops carrying M14 rifles firing 7.62 mm ammunition were also tested.
Several of the M16A1 rifles were damaged on the day movement course
after being used as steps to enter second stories of buildings, or in
bridging ditches or being dropped climbing over obstacles. The A2's
withstood all the rough handling, and three rifles were additionally
dropped six times each at varing heights from 1 metre to three metres
onto concrete and remained functional. The rifles were also abused by
launching grenades repeatedly, resting the butt against trees or hard
ground. Several M14 stocks broke under this treatment. None of the A2s
did. Overall hit probabilities for firing at "E" silhouette targets
from prone supported log or foxhole positions was about equal for the
M16A2 and M14, being about 60-70% at 600 yards, 50-60% at 700 yards,
and 50% at 1000 yards. This is firing issue M80 or M855 ammunition. The
M16A1s firing M193 got 50% hits at 600, but were unablke to connect at
the longer distances. I have fired M16A1 rifles myself under range
conditions and gotten up to 70% hits at 600, but had not been run to
death on the day movement course first! In the ambush simulations the
M16A2 scored almost twice as many hits as did the M16A1 in firing short
bursts. If both 5.56 mm rifles were fired semi-automatic only, in rapid
double-taps, the hits improved, and there was no difference between
weapons, except that the M14 took more recovery time and you couldn't
get as many rounds off.


	Ed Harris at The Black Cat's Shack (Fidonet 1:109/401)
	UUCP:      ...!uunet!blkcat!417.0!Ed.Harris

From: (Ed Harris)
Newsgroups: rec.guns
Subject: 7.62 NATO ammunition
Keywords: ammunition, 7.62 NATO
Date: 13 Sep 90 16:57:30 GMT

US manufacturing practice is to load 7.62 NATO M80 type ammunition with
Olin Ball WC846 type propelant and 5.56 mm M193 and M855 with Olin Ball
WC844 propelant.  In the case of 5.56 mm ammunition the Ball propellant
was preferred because extruded tubular single-based powders could not
obtain the required velocity without exceeding the alowable chamber
pressure.  This is described in detail in The Great Rifle Controversy
by Ezell, and The Black Rifle by Ezell and Stevens.  If a suitable Ball
propellant is selected there is no particular reason the chamber
pressure should be higher.  As for US ammunition in 7.62 NATO caliber,
the lot oaded with extruded tubuar single-based propelants such as
IMR4895 or IMR4475 usualy produce higher chamber pressures than lots
produced with Ball propellant.  There were some problems with excessive
fouling from powder residue with Ball propelants produced prior to about
1970, but this was traced to excessive calcium carbonate added in the
lacquer stil when the powder was produced by salvaging WWII cannon
powder. The specifications were later changed to limit CaCO3 content to
not exceed 0.25%, and to eliminate it eventualy from US military
production.  Current US military Ball powders are all made from new
nitrocelulose base material and contain no CaCO3 at all.  If you
require additional references on this I can look them up, but it wil
take some time.  The main work on this was done by Stiefel and Brodman
at Frankford Arsenal, Philadephia, PA about 1969.


	Ed Harris at The Black Cat's Shack (Fidonet 1:109/401)
	UUCP:      ...!uunet!blkcat!417.0!Ed.Harris

From: (Ed Harris)
Newsgroups: rec.guns
Subject: Re: Round size vs. penetration
Keywords: ballistics
Date: 20 Sep 90 18:13:59 GMT

In article <> (Peter Cash) writes:
>I've wondered about this too. The trend in military rifles seems to be
>toward ever smaller calibers. I've heard of several rifle designs that fire
>.17 caliber bullets. The reasoning behind this is that you can
>carry a lot more small-bore ammo than you can of, say, 30-06. Also, small

I have spent most of my adult life testing and evaluating military and
small arms ammunition and protective equipment, either for government
agencies or their contractors.  Every time caliber has been reduced the
effect has been to reduce penetration.  Although "energy density" in
terms of kinetic energy applied per unit area goes up, the aerodynamics
of lighter projectiles, and the dynamic instability of long, pointed
boattail bullets in soft target impacts, reduce penetration.  The
reduced penetration is not a had thing when you are looking at an
incapacitant to kill or disable enemy personnel.  The 7.62 NATO M80
Ball cartidge used in the M14 rifle begins to yaw after about 20-25cm
of penetration in gelatin tissue simulant, and does one "flip" coming
to rest in a base-first orientation after about 65 cm of total
penetration.  In comparison, the 5.56 mm M193 type round used during
the VN war in the M16A1 rifle behaves quite differently depending upon
the impact velocity, and the thickness of tissue hit.  At high striking
velocities above about 2700 f.p.s. -- combat ranges less than about 100
meters -- the bullet usually fragments upon striking pieces of
individual field equipment or bone, and at very close ranges  less than
50 yards will fragment in soft tissue even if no bones are hit, when
the body part struck offers a thickness of 12 cm or more.  In hits
through the extremities the 5.56 mm M193 round and the 7.62x39 Type PS
used in the AK do not produce terribly severe wounds, but rather like
those resembling lower velocity pistol rounds like the 9x19 Parabellum.
A hit through the thigh muscle with a 5.56 mm round is quite another
matter, and the casualty will be a long time in rehab.  The current
USSR rifle cartridge, the 5.45x39 Type PS, used in the AK-74 rifle has
a long ogival-nosed 53-gr. mild steel cored projectile with has a
hollow cavity in the nose of the jacket.  This does not deform upon
impact in soft targets, but serves to shift the center of gravity of the
projectile to the rear, increasing its overturning moment, and
consequently, inducing an early yaw of the projectile within the first
7-10 cm of penetration.  Although the lower striking energy and
velocity of the AK-74 round reduce its kinetic energy compared to our
5.56 mm ammunition, its early soft-target yaw, and low recoil impulse,
which aids control in burst fire, greatly increases the potential for
multiple hits, and a calf or arm would from such a round would cause a
much more severe wound which would require evacuation to a rear area,
rather than treatment in a field medical facility.  As for hard target
penetration, the small caliber rounds are not effective against modern
combat vehicles or aircraft, because of their lower kinetic energy.  To
be completely honest, even 7.62 NATO caliber ammunition is ineffective
to engage IFV's, and the sensible approach is to use the cal. .50 or
larger weapons.  For more data on the performance of the M16 vs. the
AK-47 and AK-74 you might look up my article in the Gun Digest, 40th
Edition, (1986) p.6.


	Ed Harris at The Black Cat's Shack (Fidonet 1:109/401)
	UUCP:      ...!uunet!blkcat!417.0!Ed.Harris

From: (Ed Harris)
Newsgroups: rec.guns
Subject: Re: Round size vs. penetration
Keywords: ballistics
Date: 23 Sep 90 17:22:02 GMT

In article <> (William B. Thacker)

>Since metal armor was first employed on warships, penetration has
>been thoroughly studied.  The physics involved are quite complicated,

The Navy criterion for penetration in armor plate may be relevant when
you are firing form-stabilized, long rod penetrators of heavy metals,
but in my evaluation of small arms projectiles against typical
battlefield targets, the comparison isn't valid.  You have to consider
that as a bullet deforms its frontal area increases.  Also, in the case
of a round such as the cal. .50 API M8, how much of the kinetic energy
is dissipated in shedding the jacket before the core is able to do the
job.  Also, you must consider the effect of oblique impacts and
gyroscopic stability of spin-stabilized projectiles.  The folks at
Applied Dynamics in Levittown, PA have modelled some of these
circumstances, but you get radically different behavior in soft target
vs. non-elastic impacts.  Everyone thought that when we tested the
older M193 5.56 mm Ball in the 7" twist M16A2 that lethality would be
reduced, but it in fact increased somewhat due to greater rotational
energy of the projectile which resulted in a shorter "neck length"
from the initial entry of the projectile until it started to yaw in a
soft target.  Fragmentation of M193 ammunition with either 90/10GM or
GMCS jackets was not significantly increased from that observed in test
firings of the same ammunition lots in 12" twist M16A1 rifles, and in
fact was less severe than fragmentation of SS109 reference ammo fired
as a control.  What does this do as far as Hague convention? Nothing,
for despite several years of arguing, these rounds did not produce any
more severe wounds in animal testing than did "allowed" rounds of past
wars.  If you want to see a really destructive small arms round, try
shooting a 100 kg pig with .303 British Mk.VII Ball!


	Ed Harris at The Black Cat's Shack (Fidonet 1:109/401)
	UUCP:      ...!uunet!blkcat!417.0!Ed.Harris

From: (Ed Harris)
Newsgroups: rec.guns
Subject: Re: Wound, not kill
Keywords: ammunition, 5.56mm
Date: 23 Sep 90 17:26:07 GMT

In article <> (Joe
McConnell) writes:

>In article <> writes:
>>Wooden bullets were designed to wound rather than kill. The
>>Some of this same logic went into the selection of the small, fast, 5.56
>>round as the main US combat rifle round.
>Could you cite one or more sources for this (often-heard) idea?

Aberdeen Proving Ground Techinical Reports:

A comparison of Proposed Small Arms Weapons Systems, MR No. 1139, Apr.
1958; Effectiveness Study of the Infantry Rifle, Hall, MR No.593,
March, 1952, Penetration of Experimental .22 cal. Bullets in Gelatin,
MR No.1109, Oct. 1957; Probabilities of Incapacitation of cal. .30 Ball
M2, MR No. 949 Dec., 1955; Design and Fabricatw A High Velocity .22
Cal. Cartridge, 25th Report of Project TS1-2, Spet., 1953;

You can also find the full historical record, appropriately referenced
in The Black Rifle by Stevens and Ezell, ISBN 0-88935-042-6, Collector
Grade Publications, Inc., Toronto, (1987), available in the UK from
Greenhill Books, Lionel Leventhal, Ltd., Park House, 1 Russell Gardens,
London, NW119NN.


	Ed Harris at The Black Cat's Shack (Fidonet 1:109/401)
	UUCP:      ...!uunet!blkcat!417.0!Ed.Harris

From: (Ed Harris)
Subject: Re: M-16 at 1000 yards (was Re: Destructive devices (.50 BMG))
Date: 9 Dec 90 18:19:49 GMT
Organization: FidoNet node 1:109/417.0 - Silver Bullet, Frank Mallory

Don't know what the original message was, but I am one of the only 
people crazy enough to have attempted to fire an M16 at 1000, which I 
did at Camp Perry in 1972, along with some other fellows from the Navy 
Atlantic Fleet Team.  We shot handloaded 68-gr. experimental FMJ 
bullets made by Sierra in 9" twist barrels, and the weapons had 
Redfield International rear sights.  The ammunition and weapons had 
some obvious similarities to the M16A2.  We managed to keep all the 
rounds on the frame, but that was about it.  Later in 1980-81 I 
assisted in the Modified Operational Test of the M16A2 at the Marine 
Corps Development Center at Quantico, and we fired the M16A1E1 which 
later became the A2 at ranges back to 1000 yards.  We were able to get 
about 50% hits on "E" silhouettes with FN SS109 ammunition, if the wind 
was not too bad, about 70% at 800 and 80% at 600 yards.  This was with 
master and Distinguished level MTU shooters.  In normal field 
experiments on the day movement course, KD firing in the field range 
course, daytime and nighttime ambush scenarios the hit probability was 
a significant improvement over the M14 and M16A1 at the shorter ranges 
up to 300,not different from the M14 from 300-600, but inferior to the 
M14 beyond 600, as you might expect.


   	Ed Harris,
   	via The Black Cat's Shack's FidoNet<->Usenet Gateway   and   Fidonet 1:109/401

From: (Ed Harris)
Subject: 5.56 M855/SS109 twist requirement
Date: 20 Jan 91 15:44:12 GMT
Organization: FidoNet node 1:109/417.0 - Silver Bullet, Frank Mallory

The reason for the 7" twist was mainly to stabilize the M856 tracer 
bullet, as there was a requirement for a bright trace to 800 meters for 
use in the M249 Squad Automatic Weapon.  Although a 10" twist as used 
in the pre-1986 Ruger Mini-14 will stabilize the M855/SS109 bulets at 
normal ambient temperature, the gyroscopic stability factor is only 
about 1.2, which is marginal and does not give a sufficient margin of 
stability for military use.  To obtain a gyroscopic stability factor of 
1.3 or greater, which is about the minimum acceptable would require a 
9" twist.  For military use you generaly want Sg to be in the range of 
1.5-2.0, which could be obtained with an 8" twist.  The 9" twist would 
be better for taret shooting, as it would minimize the effect of a 
higher angular rate of spin upon dispersion if you had bullets which 
were not of the highest quality.  With perfect bullets which are well 
balanced, more than adequate twist does not hurt until you get to a 
gyroscopic stability factor greater than 5.0.  I have shot the 69 
Sierra MK in 7" twist barrels from the .22-250 at 3400 f.p.s. with half 
minute of angle accuracy, using a heavy test barrel on a benchrest type 


        Ed Harris,
      via The Black Cat's Shack's FidoNet<->Usenet Gateway
   and   Fidonet 1:109/401

From: (Ed Harris)
Subject: Re: AR-15 forward assist, why?
Organization: FidoNet node 1:109/417.0 - Silver Bullet, Frank Mallory

My experiences with the M16 lead me to believe that the forward assist 
is a curse for troops in the field, because they will bang on the thing 
willy nilly instead of taking the recommended "immediate action" of 
extracting the offending round and letting the bolt blam home.  I have 
repaired at least a truckload of rifles in which the troops tied the 
thing up worse, and you could neither force the bolt closed or get it 
open.  We had to clear the things by driving out the takedown pins, 
remiving the lower receiver, and then with a brass punch and lead 
hammer driving the bolt carrier out the rear of the receiver.  You 
can't do that in the field.  The solution is to train troops to clean 
the damned chamber, keep their ammo clean, and to keep the ejection 
port cover closed.  When you load the rifle, insert a loose round in 
the chamber and with the muzzle pointed in a safe direction drop the 
bolt on it, then insert the magazine and give it a stout rap to ensure 
it is seated.  When you reload, if you have not shot the magazine empty 
so that the rifle has gone to boltlock, latch the bolt carrier back, 
drop the old mag, insert the new one, then tap and drop the bolt with 
the release lever rather than using the charging handle!  Most problems 
are caused by troops using the charging handle and riding the thing 
down, instead of letting the action spring drive the bolt carrier to 
give it enough interia to do its job properly.  TRAINING, TRAINING, 


        Ed Harris,
      via The Black Cat's Shack's FidoNet<->Usenet Gateway
   and   Fidonet 1:109/401

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