From: liats3@cspyr1.cs.adfa.oz.au (LIANG TIAN)
Newsgroups: sci.military
Subject: Re: M16A1 ammunition vs M16A2 ammunition
Date: 23 Jul 92 18:36:22 GMT
Organization: Australian Defence Force Academy, Canberra, Australia


From liats3@cspyr1.cs.adfa.oz.au (LIANG TIAN)

Eugene Heiss (GWD) <heiss@brl.mil> writes:


>From     Eugene Heiss (GWD) <heiss@brl.mil>

  Not this thread again!

>>From: fist@iscp.Bellcore.COM (Richard Pierson)
><If you have been reading this news group and rec.guns you will
><probably be aware of the discussions on this. The M16A2 and the
><M248 SAW use a heavier bullet with a heavier charge, while cartridge
><dimensions are the same performance is not, the gases generated in
><the heavy ball exceed the normal 5.56 round and over a period of
><time will damage the AR15/M-16A1. 
>This is not true.  The M855 Ball cartridge was designed to be compatible
>with the M16A1 Rifle.  The pressure vs time curves are the same for the
  I don't know their pressure-time curves but isn't the M855 the US
name for the NATO standard SS109 round. I don't think FN would go
to the trouble of making their new round compatible with the old
M193.
>M855 SAW cartridge and the M193 M16A1 cartridge.  The internal components
>of the M16A1 were not changed in the conversion to the M16A2.  The gas system
>of the M16A1 is the same as the M16A2.  In the Sierra Bullets Reloading
>Manual, the maximum advisable loading for their 55 grain bullets (same
>weight as the M193 projectile) would give a velocity of 3200 fps while 
>that for a 63 grain bullet (the M855 bullet weighs 62 grains) is 3100 fps.
>These velocities are the same as those obtained by the M16A1 and the M16A2,
>respectively.  Because of legal problems, there is no way that Sierra would
>list loads that would damage a commerial version of the M16.  In fact, their
>testing was done with the AR15 which was the original M16.       

><While I have not personally fired
><the older round in the saw I would think that it would be suceceptable
><to jams in low speed.
>Why?

>< I don't for sure know if there is any danger
><in mixing ammo, an armourer from 10th mountain said "don't" and that
><I turn in my A1 and draw one of their A2's if I wanted to live fire
><with their ammo so that was good enough for me, it might be different 
><if the weapon had a variable gas port like all the others in the 
><world then you could fire anything. Of course we Americans like
><to redesign the wheel over and over again
>There is no problem in mixing ammunition as far as reliability is concerned.
>You will probably not hit as well shooting the M855 in the M16A1 than if you
>used the M193.  There will be no discernable difference between the two 
>cartridges in the M16A2.
  During the last time this thread surfaced(about 2-3 months ago),
there was a post that said the M855(SS109) round will suffer !serious!
accuray problems when fired from AR15/M16A1 (1/12 rifling). This is
stuff like round tumbling very early and hitting target at 100m
!sideways! The M193 round, however, will work satisfactory with the new
rifling. Though with less accuracy than in the old barrel.

/***********************************************************/
				Liang Tian Soon
				liats3@cspyr1.cs.adfa.oz.au
/***********************************************************/
Newsgroups: sci.military,soc.history