Have you tried it with the bolt locked open?

 

If the cheap turknelli is anything like the legit M4, I just pull the bolt back on mine and keep it locked backed, unscrew the magazine cap, make sure to catch the spring if you have removed the safety plunger or if the turknelli has it, and slide right off. The handgaurds will kinda just fall off to the side.

 

Did you figure it out I am having the same problem

 

I have the same issue. I think its the handguard. I have pull HARD to get it off. I cleaned it all up and went to put the barrel on but it has a gap. A gunsmith sais he didnt like the diamater of the mag tube but I think its more the armguard in general or the barel has an issue going on inside the chamber .

 

Same issue

 

I have a similar issue, it clearly seems to be because of the hand guard rail.
So after playing around with the rail, I noticed the rail was off in the front of the shotgun due to misalignment. Once aligned where it should be, the issue was fixed.

 

Mine was just a really tight fit at the barrel shroud. With the bolt locked to the rear, and the mag cap off, if you let the bolt slam forward, it actually pushes the barrel out a bit. Several times taking it apart loosens it up a bit.

 

I just looked at it again and you also have to take off the barrel clamp which attaches to the magazine tube.

 

I ended up dremeling out the handgaurd around the front and back to deepen the fit. I had to scrap out the curved part the retaining ring fits into. Now it fits and its snug. Some people had to make it wider. Just deepen it first then go from there. It doesnt fit right.