Been reading this thread with interest and another more recent one about corrosive ammo. First let me say, I am one of those folks that believes you should have a habit of cleaning your firearms the same day, if not the very next day, no matter what type of ammo you use. But that's mainly because I'm one that feels it's just part of responsible gun ownership. With that said, if you know you aren't firing corrosive ammo, then really it boils down to how motivated or lazy you tend to get after an exhausting day at the range. Just so no one thinks I'm a purist or have NEVER failed in this, well a couple months ago I decided to do a trigger job on one of my Ruger 10/22's. It had probably been since the first of June or maybe even May since I last fired it. Since I am religious about cleaning my guns after shooting them, I was appalled to find I had not on this 10/22! Of course, non-corrosive ammo meant nothing bad had happened. Now, had that been one of my SKS's, Mosin's or AK's which I shoot corrosive almost exclusively, I would have been in for a surprise.
However, while I often see the topic of non-corrosive vs corrosive ammo and how you should handle it, come up often, one thing that doesn't seem to be talked about it how much real damage is done and how that damage will affect the firearm's performance. I had always wondered, until I bought a 1949 SKS a couple years ago, that had been seriously rode hard and put away wet. I bought it from a gentleman at a gun show on a Saturday, took it home, tore her down to find an amazing amount of corrosion and decay. It was late and I had no time to deal with it that night, plus I didn't think another day one way or another would matter. The next day, at the same gun show, I actually asked the seller about it. It had been his personal firearm and not something he had taken in trade, so I asked him when the last time he shot it was. He thought for a moment and said probably about 10 years. I'm sure I had "that" look on my face as I walked away, starting to really wonder what I would find once I started attacking the problem. I, like the OP, had to use a punch and mallet to carefully get the piston out. I didn't think to take pics of that before I went at it with a mix of Hoppes #9 Plus, CLP/Gun Oil and some Gun Scrubber.
But, here are pics I did shoot of the gas port before I cleaned it. That is an amazing amount of carbon buildup and to be honest, at first I thought it was mostly corrosion. I was actually wondering if it would negatively affect the bolt operation and gas pressures. At some point I thought perhaps I could "chisel" the "corrosion" off or at least smooth it down and thinking there couldn't be anything further I could do to damage it, I grabbed an actual thin wood chisel. It did start flaking off, but I was pleasantly surprised that what I thought was corrosion was simply a massive amount of carbon buildup! This HAS to be thousands of rounds of build up without cleaning, over time.
And after cleaning. Seems to have staved off serious damage.
Here is a picture of the piston and the pitting and corrosion caused by corrosive ammo.
Also, the bore was a serious sewer pipe. As bad as anything I've ever dealt with on my many Mosin's. Being that a '49 does not have a chrome lined bore, I was really regretting my purchase. As you folks know, SKS's are not cheap down in the states and a '49 commands a premium. I still got what we would call a good deal ($400) for a '49. The bore was very dark and fuzzy. I couldn't even see and lands and grooves and when you take that first 6 or 7 swabs, you literally have to slowly smack your hand on the handle to get the brush through. After about 2 hours and a plethora of different cleaning agents, here's what I found.
In that last pic, you can see that not cleaning this firearm has taken a bit of a toll on the bore with obvious pitting, but surprisingly, not too bad. The lands and grooves are still fairly sharp. So if the guy hadn't cleaned it in over 10 years, well...Not bad all things considered.
My whole point in this reply is to say that there's really no reason to fear shooting corrosive milsurp ammo. While I still believe I should clean my firearms right after use, I'm not going to lose sleep over it, if it happens the next day or even the next week. If I absolutely cannot get to it soon, I simply just run a dripping wet (with tap water) patch through the bore a few times and call it good. I'll pop the gas tube off and throw the piston, bolt and carrier into a Hoppes #9 Plus solution and rinse out the gas tube. Then, if it's a few days before I get back to it, nothing will have happened.
This girl has lived a hard life, but she still shoots as well as any of my other SKS's.
