Is this bad??? 30 Carbine

[rtracy2001]

I was cleaning the carbine this afternoon after shooting cast for the first time in the Carbine. It was also the first time I have ever torn it sown this far. When I pulled the gas piston out, I noticed a crack in what I assume is called the gas block (underside of the barrel where the gas piston is). Is she a goner, or is this a non-issue. On the upside, I didn't notice anything that looked like leading in the barrel or gas system.

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[30Carbine]

Ok i'll answer this one been there done that I have had 4 of these do that. if you can weld or know some one that can it is fixable. spot weld it right at the piston opening in the thin spot, then hand file it back down I repeat hand file only no power tools. will be good to go. it is caused at least in my case of pushing loads to fast to much pressure to quick. I did the last one in july when I was trying to push over 2400 fps. also over tightening the nut will crack it there also. i'll post a pic in a few minutes to give you an idea let me break one down real quick.

[30Carbine]

ok here is the pic this one is from over tightening the nut. DON'T OVER THIGHTEN NUT. pics a little fuzzy the phone didn't want to focus that close but you can see the hole and shinny spot from filing.

[rtracy2001]

So it is time to break out the welder. MIG OK? Or should I find someone with a TIG unit? I imagine I will have to chase those threads after welding. Do I need to leave the angled hole, or is it just a remnant from where the gas port was drilled?

[30Carbine]

I just leave the angled hole and yes I use a tig cause I have one you should be able to do it with a mig. and yea chase the threads when done.

[rtracy2001]

Finally got a minute to break out the welder and get the old girl patched up. Went pretty smooth. Chasing the threads was a bit of a nail biter, but I got through it. I even found a nice gentleman in France to sell me an unissued gas piston and nut (eBay works). I also installed all new springs. Looking forward to trying her out soon.

[jimb16]

Why did you remove the castle nut and piston in the first place? You almost never need to do that! They are basically self cleaning. And if they ever do get "stuck", all that is needed is a good solvent soak for a couple of days and another trip to the range. Tools for removing the nut were issued only to the unit armorers because the nuts were staked in place and were not meant to be removed. Removal and replacement often result in cracked gas cylinders. When removed, it is very important to properly chase the threads before trying to replace the castle nut. If you don't, you run a very high risk of cracking the cylinder and destroying the barrel.

[rtracy2001]

The piston nut was loose and came out without tools. Then I noticed the crack and significant erosion under the head of the gas piston. I had to chase the threads after welding anyway.

I don't think I will stake the new one in place. In a battle situation it makes sense. Less to worry about. In a plonker that gets babied, not so much.