The way I understand it, as long as you shoot non corrosive ammo I can let my AR barrels go for quite a while between cleanings with no ill effects as compared to using corrosive ammo. I have a few questions:

1. Are the major companies' ammo ( Federal, Winchester,...) corrosive or non corrosive?

2. Is it the type of poweder or the type of primer used that determines whether ammo is corrosive or    not?

3. What happens to barrels not cleaned right away after digesting corrosive ammo?

4. How can one determine whether ammo is corrosive or not?

Thanks,

Gunz

P.S. One of my barrels is stainless (BM CMP 1/8) and one is chrome lined.

unless you shoot surplus ammo i wouldn't worry about corrosive ammo.  
i shoot a lot of 8mm which is corrosive and i clean with windex with ammonia and hot water before
cleaning with hoppes#9.

i barely ever clean my ar15 barrel, it's chrome lined so i don't really worry about it too much.
1. NC
2. primer i think...
3. rust, frosted bore, pitting
4. ask the dealer where you buy it.  usually says on the box if it's NC or C.

Quoted: The way I understand it, as long as you shoot non corrosive ammo I can let my AR barrels go for quite a while between cleanings with no ill effects as compared to using corrosive ammo. I have a few questions: 1. Are the major companies' ammo ( Federal, Winchester,...) corrosive or non corrosive? 2. Is it the type of poweder or the type of primer used that determines whether ammo is corrosive or    not? 3. What happens to barrels not cleaned right away after digesting corrosive ammo? 4. How can one determine whether ammo is corrosive or not? Thanks, Gunz P.S. One of my barrels is stainless (BM CMP 1/8) and one is chrome lined.

1. ALL US made commercial ammo is non corrosive.

2. It is the PRIMER that makes it corrosive, not the powder.

3. They rust. Given enough time they will pit.

4. Stay with commerical US ammo or USGI ammo (.223) as it was never made with corrosive primers.

Thanx for the info. I feel better now I usually clean my rifle right after using it but my stainless barrel has sat uncleaned for a long time.

Gunz

A good black powder solvent works well for chlorate primed ammo also.Hoppe's#9 plus,MPC's CAC-10,Thompson Center old No.13 just to name a few that works great.
I prefer the CAC-10 due to the fact it works faster and contains FP-10 for corrosion protection.
But they all work well.
The most cost effective way to do it is a hot water and soap cleaning.Only takes one patch for cleaning and a couple to dry.
Get yourself a pan of hot water and mix in a little dish washing liquid like Dawn etc.Run a tight patch down the bore to the muzzle.Stick the muzzle in the water/soap and slowly draw the water/soap up into the barrel.Keep the patch in the bore and do not draw it back into the chamber or out the muzzle or you will loose suction on the water/soap.Pump the water in and out of the bore slowly.Change the water when it gets cloudy,and continue to clean.Once the water and soap remains clean pull the patch back into the chamber and swab it...finish by pushing the patch through the bore to the muzzle.Rinse the pan and fill with hot water and use the same procedure to rinse the bore and then mop the chamber.Then dry patch.The bore will be hot from the hot water and will dry fast and completely free of oil,so move to your bore solvent or oil as soon as possible.
Also wipe the breech,bolt face,firing pin tip or any part that might have primer salts on them.
I would use a good copper solvent after removing the corrosive salts and powder fouling from the bore.Removing the copper from the bore with a copper solvent gets at the salts hidden under the copper.If the copper is not removed the bore will rust under the copper from the primer salts in time.
Also after using the ammonia based copper solvent run a patch of isopropyl alcohol down the bore to remove any ammonium salts from the copper solvent.Dry the bore real well and then oil.
Good to go.
Personally I would not shoot corrosive ammo in a AR15 due to the fact it would be darn hard to get the stuff out of the gas tube and from around the gas port and front sight housing.Those areas could be an issue.
Bolt guns and auto loaders like the M1 are much easier to deal with though.
I shoot corrosive ammo in my Enfields,M1,MN's and mausers all the time with the above procedure and or products with no problems.
The rule to follow is "never let the sun set on a dirty weapon."Clean as soon as possible and make sure its clean.
Do a follow up cleaning with Hoppe's #9 etc. a couple days later to remove any gas fouling.
hth
Raymond