I was reading the other day and someone said that some of the older SA 5.56 is corrosive?! Is this true? I just bought two battle packs to *try* at a gunshow, because of all the good things I hear about it on here. But if it's corrosive I won't have anything to do with it..

Thanks.  

Found this over at toads site. FWIW it seems some surplus 5.56 is mildly corrosive.

hk54.gunserver.com/forums/showthread.php?s=95b30dbd434740dcb9f14cdd8a40a7d3&threadid=1169

I shoot a lot of SA in my mini. Bolt was starting to get a little sticky so I field stripped it and sure enough there was a light coat of rust on the gas nipple. Had about 1000 rounds through it over a period of a couple months.

I wouldn't worry about it. It cleaned up easily. Its not like the old WW2 stuff which will rust up your gun before your eyes.

I've never heard of the SA BP ammo being corrosive.
I have shot buttloads of the M1A3 lot and am about to start into my M1A4 lot - No problems.
Then, I always clean my guns within 24hrs after shooting, usually right when I get home.

i've shot close to 1k rnds of it over the last 2 years. Usually left the rifle for over a week before cleaning with no problems at all. Of course this was sitting in my gun cabinet in A/c. So i am sure that reduced the moisture somewhat.

Shoot it. If your worried just give it a quick clp spray down the bore and bolt to dissolve the salts and coat the metal. With proper care corrosive ammo is no problem.

Over the coarse of about 6 months, I shot SA as well as some PMC through a ar15, without cleaning it after shooting.  The main reason for not cleaning my rifle for that long of a period was to see how many rounds I could get through it before it started to have problems.  At no time did I ever see any corrosion on anything.  The SA was '85 and '86 m1a3 stuff.

Ended up the reason I finally cleaned it was not due to it malfunctioning, but that I just couldn't let it sit there dirty any longer.  So as for my original purpose in deterimining the reliability of my rifle, I sort of failed, due to a lack of self-control.  

As for those who may wonder what the round count was, it was at 450.  This was over roughly 6 or 7 outings with the rifle.  Sometimes I would only maybe shoot a mag worth, sometimes 150 rounds would get shot off.  I am not a high volume user of ammo as one can see.

Hi,

The lot of M1A3 '85 I have is mildly corrosive. I noticed after I shot 50-100 in my AUG and forgot to clean it. After a week I noticed some rust on the tail of gaspiston, although not much.

In my AR's or SIG I never noticed this before.

Cheers,
RG.nl

I think it is corrosive. I cleaned my AR180B and the patch came out rust colored. It will show up in a non-chromelined barrel if you do not clean it right away. A chrome lined barrel should resist the corrosion. Some time this week Ill try to test it on a peice of steel. All in all, I am VERY dissapointed.

If you are concerned, test it. Get a piece of mild steel, clean/polish an area with sand paper. Pull the bullet from a sample cartridge. Place a small sample of the powder on the cleaned steel and ignite. Pop the primer from the cartridge, directing the gases against the cleaned area. Place the steel in a humid area (I use my basement) and watch for accelerated corrosion in the test areas.

Doh! Should have read the whole thread... looks like Frank is going to do the test in the post just before mine.

After reading the thread I checked my AR's. Its been a few weeks since they were last shot and didn't get cleaned afterwards.  The non-chrome barrelled ones had a light coating of rust. Cleaned up easy enough but still not good. Not sure of lot numbers.

Thoughts on what to do to the gas tube? Don't put any lube in it or clean it at all normally. Should I shoot CLP up in there, use something else, leave it? I don't want to replace the gas tube due to it rusting through.

My understanding is that truly corrosive ammo was due to some mercury compound in primers used before the 70's (I think I saw this in Speer Reloading manual).  No primers made in the last 30 years or so should be corrosive (of course there could be some 60's made primers in the early 80's ammo).

The SA I've shot which I bought in 1997 (several thousand rounds) showed no signs of mercuric corrosion, but it was kind of dirty - although not Cheaper Than Dirt!  

There will always be some tendency to rust in any combustion process with any powder or primer because water vapor is formed and if left to condense... what else is there to expect?  Water on steel in the presence of oxygen yields rust but not the true acid type corrosion generated by "corrosive" ammo.

Does anybody know of any stainless bolt carrier keys?

Update:  Speer Reloading Manual #13 pg 34 says corrosive ammo was due to potassium chlorate that replaced the mercury fulminate.  It was used until the late 20's except by the US govt. which discontinued it's use in the 1950s.  No indication about South Africa however.  If PMP can tell you whether lead styphnate primers were used in your lot, then you can be sure the 'corrosion' is not caused by the primres.  It's just moisture and powder residue doing the damage.

I've been told gas tubes won't clog due to the high gas velocity but I've never thought about corrosion.  I always swab mine with one of those long pipe cleaners & either CLP or KROIL; then blow it out with 100 PSI dry air from the compressor.  Haven't had to replace one yet.

Quoted: I've been told gas tubes won't clog due to the high gas velocity but I've never thought about corrosion.  I always swab mine with one of those long pipe cleaners & either CLP or KROIL; then blow it out with 100 PSI dry air from the compressor.  Haven't had to replace one yet.

thanks KEA..time to buy an air compressor.

Sounds like the people that have the rusting problems are the ones that don't break down and thoroughly clean thier rifles soon after shooting or don't clean them for a few weeks. Lots can happen in that time especially depending on your storage area and whether it's humid at all. Like KEA said the combustion process can cause rusting if you don't clean your rifle. I shoot corrosive ammo in my Mosin Nagants and never had any of the problems that anyone here has mentioned because I clean it after shooting. I guess that's the moral of the story....clean your rifles.

I agree with Rob01.  I use to be a range instructor, and I also worked in a gun shop for about 6 years on and off.  And even with corrosive marked ammo, like some of the Chi-com. 7.62x39mm, if one cleans their rifle sometime that day, after shooting, then all is well.  No ammo is truely non-corrosive due to the ignition process of powder, and temperature changes in the barrel.  The real enemy is humidity, and poor P.M. on the weapons.  As old Sarge R.Lee Ermey would say "you had best square your ass away, and start shitting me tiffany cufflinks".

OK, I'm going to get slammed for this.  

I shoot WWII ammo all the time and my rifle parts are spotless.  Bull you say or how come!  I clean the rifle.  My amazement never ends at you civilian shooters (never been in the military) that pout about corrosive ammo. Hell, I didn't know that early 5.56 was corrosive and probably shot 1,000s of the stuff till I got on this site.  You couldn't find a spec on my M16.

I can understand "Bert, from Tremours Movie" that wants to know how long he can go without cleaning, but hey my AR has a butt stock cleaning kit so I never thought about it until he mentioned it. Hate to kill a good AR but would like to know just for the hell of it.  I know one of you pro's from dover has the spec somewhere.

I'd rather have acuracy and reliability than corrosion resistence any day. Acuracy and reliability will save your life. Give me the SA over Wolf any day.  All corrosive ammo means is you better clean your rifle like you should have anyway. Clean her up right and the barrel will wear from use long before the ammo corrosive properties has any impact.

There are plenty of free sites that will tell you how to properly clean your rifle.  

Sorry guys, it's hard for me to relate to this topic after shooting 1932 phosphor bronze boat tailed 8mm stuff in a non-stainless 60 year old metal rifle with no problems.

Tom I now what you're saying. I was ready to get slammed for saying what I did but got 2 positive posts. It seems like a growing trend I've seen about people not cleaning thier rifles and bragging about it because they still get good accuracy. I'm not just talking about this site but many others I visit. I guess the Marine Corps just burned it in my head that my rifle should be clean. I almost break out in hives if I don't clean it for a couple of days after shooting. I know that over zealous cleaning is bad but not cleaning is worse in my book. Just a quick few patches of solvent and some oil at least. Also totally break it down every now and then. Well enough on the subject. I hear the slammers coming. ;)