I watch alot on The Military Channel. Lotsa good stuff on there. And of course alot on Nam. One thing I notice is most of the time the rifles have 20 round mags and not 30s. It seems later on in the war the 30s show up more esp. in the carbine length weapons. Any reason for this?

Yes. I can say from my experience, line units were only issued 20 round mags in 1970. I saw very few M16 30 round mags and they belonged to Special Forces, SEALS, Rangers. Unfourtunatly the NVA and VC had them for AK's.  
Too, they were not as prolific as 20 rounders at the time.

A Vietnam vet. A salute to you Sir. What the hell was the logic behind that? Save money on ammo? Magazines? I dont get it.

Quoted: A Vietnam vet. A salute to you Sir. What the hell was the logic behind that? Save money on ammo? Magazines? I dont get it.

Probably the same reason they switched from auto to burst: soldiers panicking in combat and spraying on full auto. You can do less damage to friendlies with 20 rounds than 30.

And I salute you as well, Slick. God Bless.

The only reason the 30rd mags were created was cuz the military complained that the NVA had AKs with 30rd mags so they made them for the AR..just my $.02. Thats what heard on the History channel a while back.

we still only had 20 round mags in 1979-83

I got my first 20 rd mags out of the dumpster from inside a MRE box that was stuffed. They were cleaning out the Armory, and chuckd all kinds of stuff.

Didnt they use canteen pouches to carry the Thirty's to start with?

30 round mags began to surface in Vietnam in the early 70s. Pictured of Marines with 30 round mags on their rifles are found during the evacuation of the US Embassy in Saigon following the Fall of the capitol to NVA forces in 1975.





Is a small image, but you can see the 30 round mag on the marine's M16.

the army still has lots of 20s. it is my understanding that airborne troops like to have at least 1 20rd mag because the rifle with a 30 inserted will not fit in the jump case. any airborne troops confirm this?

Stoners first idea was for a 30 round mag. Examples of 20 and 25 round mags exist in a 'waffle' style in limited mass production. I used to own a 25 rounder once so I know they exist. Now to the answer of why? Ammo conservation. Sort of a built in burst limiter I think is why they started using the 20's in it's early incarnation.  Keep troops from using long panic bursts.  Free internet advice, worth what you paid for it.......

For our Veitnam vet, thanks for going, hope you have not experienced any long term negative effects from your service.

Quoted: A Vietnam vet. A salute to you Sir. What the hell was the logic behind that? Save money on ammo? Magazines? I dont get it.

20 rounders were standard issue long before 30 rounders. 20 rounders were much more prolific at the time, so naturally the first USGI 30 round M16 magazines went to SF/LRRP/SEALs, etc. Same way you see lots of "new" stuff hitting the SOCOM units first today.

I was in Vietnam and Cambodia during most of 1970 with B 5/7 of the 1st Cav Div.  We had only 20 rounders.  I never saw a 30 rounder while I was there.  Personally, I hate the 30s because you can't get the rifle really close to the ground when firing from the prone position which is the most common firing position in jungle warfare.

I was in Viet Nam in 1968 & 1969.  I was in the Army and wasn't a field grunt, but worked in communications.  I was issued an M-14 and kept it for two tours.  I went through basic in 1967 and was trained on the M-14 & M-16, since the 16 was just being phased in for most ground troops.

Four of the 20's would fit in a M-14 ammo pouch that would only hold two M-14 mags.  Never saw a 30 rounder until the 80's.

I spent 15 years as an armorer and the supply room was right across from my arms room door. Now, this is only my opinion, and probably just an educated guess, but the reason that 30 rounders weren't as common then is very simple. Supply.

They were probably made in limited quantities until they got the bugs worked out and then they were only issued to the "elite" units. As time went by they were slowly incorporated into the supply system and became more readily available to everyone else.

Now we find that the 20 round magazines have become obsolete and they are slowly being phased out of inventory. The military supply system is similar to an ocean wave. At first there is a low point where the item is just being introduced, then it crests at a high point where there is maximum production and distribution, and as it is being phased out it falls back to a low point again.

guys,
    The first dedicated 3- 30rd mag pouch had a 1966 contract date in the lid, but nobody from that time period remembers using 30 rd mags until many years later. I am working in Bogota now, but will add the contract info when I get home.
                       
                                                   Carey

Edit: January 1966 contract DSA 100 66 C 517. Natick Labs was supposedly involved
      with the development &/or manufacture of these pouches, possibly the mags
       themselves. But no CAGE info found on "Natick Labs" entity for that time period.