I'm retro fitting an Adam Arms piston kit.  My hand guard will completely cover everything, in fact I will have to have a small cut out to access the adjustable gas block.  No big deal.  

How often do I need to clean the piston set up?   I'm hoping rarely to never.  That would mean taking off the rails.  If it's often, then I will reconsider doing this.

I have one.  The bolt stays really clean. The piston not so much, if you let it go long enough you might even have trouble getting it apart eventually.

Use a different hand guard.

Thanks.   That kills that idea.  I appreciate the input before doing this.

Beleave it or not, you can never take the piston apart for the entire life of the barrel.

I have done it twice with two different AA uppers.  

Pic from upper piston taken out first 5,000rds now around 15,000. Not removed,
Check out carbon build up around block.
Piston cup that rides over gas valve scrapes excess carbon off as it cycles back and forth.
Barrel degraded thru bore erosion, Needs replacing

Yes if you don't  clean it, you may have a really hard time getting it out.
This upper I sent back to Adams Arms to have a new barrel put on...
I attached a note saying "Good luck getting the piston out!"

I guess he is right.  I just can't let my shit go without cleaning every once in a while.  I blew off the piston cleaning one summer, just hit the bore,chamber and bolt. Gun ran fine, and was starting to look like his. It was a bitch getting the piston out later.

I don't think I have ever seen anything from AA about a cleaning schedule.
PWS recommends cleaning the piston at 3k rounds fired, then cleaning the piston tube at 5k rounds fired.

Soaking the piston overnight in Motorcraft carburetor cleaner will dissolve all the carbon, residue rinses off easily.

I bought this piston kit to go on a 7.62x39 upper.  I run it suppressed 100% of the time.  I run it full auto almost always.  I use the cheapest ammo I can find most of the time.  

After 2-3 magazines I have to lube because of stoppages.  After doing that a couple of times I have to take a bore / chamber brush to it, once again due to stoppage (that lube alone doesn't fix).  

Because of the way it's set up, I can not change my rail.  I can remove it, and reinstall it.  However I can't get another one.  Briefly I have an OSS suppressor and there aren't any real choices in that diameter.  

Should I piston it or not?

Piston it.

This ten times over........

One of my concerns is shooting the very dirty x39 is that it'll gum up the piston much faster.  At least right now I can easily take out the bolt and clean it and the chamber.  

Thoughts?   Specifically related to cleaning the piston.  I won't have access to cleaning the piston often.  

This entire cluster project of an upper came to being because I bought an over the barrel OSS in 762.

Run a few hundred cartridges then check the piston.
The x39 ammo is some darn dirty stuff. You will just need to run it a bit and see how dirty it gets

You can get a Samson handguard for AA if you want. It sounds like your setup should work fine though. You only need to turn the gas key to the left to slide out the entire oprod for cleaning. What's the problem?

Edit: Oh you mean you'd literally cut a hole and the guard would continue so you couldn't slide it out. Get a Samson. I'm not aware of another handguard made just for the AA.

The issue with the handguard is that the INNER diameter has to be more than 1.75 to go over the OSS.  This Seekins rail I have is 1.8 inches.   Hard to find one with that diameter, but this one was designed with the OSS in mind.  

Edit.  I'd have a hole cut for access to adjust the gas block.  Not to remove it.  To remove the piston for cleaning, I'd have to completely remove the rail (and the purpose of this thread).  

Because it's an over barrel suppressor, I absolutely needed a pistol gas system.  Otherwise the entire upper would be 5 feet long.

Once again, all this mess started when I bought the over barrel suppressor that is OSS.  

In its final form it is nice.  It functions great, looks stellar, and surprisingly suppresses great. However getting to this point wasn't quick.   I would NOT do it over, I would not have bought the over barrel suppressor.  

It is what I have.  Trying to make the best of it.

The Samson EVO I have only has like a 1.5" clearance, if that.

You can just cut your rail like the Samson with a dremel I guess.

I'll get it milled properly.  I have to get the carrier modified as well.