I ordered the Mossberg heat shield for the 590A1 with the heavy barrel (part #16335P, $30 plus shipping.) to give it a shot. Mossberg also sent the nuts, screws and spacer (not used) with the heat shield. I have the Big Dot installed and the heat shield needs to slide down the barrel to go on. I cut a slot for the Big Dot. It is long enough for the heat shield to fit over the Big Dot when the front restriction is at the muzzle. I rounded all the corners of the slot. This way I just place the heat shield on the barrel and slide it to the rear in place. I also had to reduce the rear corner of the screw hole plate so it would clear the magazine cap. The heat shield is long enough to fit flush with the end of the muzzle. I used Brownell's Dicropan T-4 Touch Up Cream to blacken the bright steel areas from the cutting and filing. To remove the barrel just unscrew the magazine cap while sliding the barrel forward at the same time. To install the barrel place the magazine cap in place with the barrel forward and move the barrel to the rear while turning the magazine cap into position. The Big Dot clears the heat shield so it can still be used if needed. The stud sticking up in the rear heat shield photo and the full Shockwave photo is part of a C clamp I used to install the heat shield. There may be a problem with the heat shield shifting under recoil and trying to come off the barrel. I'll have to try loc-tite under the front band if that happens
Perhaps a stupid question but is there a reason that a Big Dot could not be attached to the heat shield instead of the barrel?
I didnt do any of the above builds, but i dont see any reason you could not do that. .
My plan for my heat shield is to drill and tap the shield, not the barrel, for a big fat brass bead. I would intend to do the exact same thing for whatever sight or bead I install. A drill bit and tap is like $12 on amazon...
Any movement may not be a problem. I do know that the normal installation of the heat shield requires the use of the spacer that rests against the barrel magazine loop to lock the heat shield in place. That can't be done with my installation as the mounting screws are in front of the barrel magazine loop. I've cranked down on the mounting screws and put blue loktite under the front band. This should hold the heat shield in place. There really is no room for placing anything under the band. It's a snug fit. If it does move under recoil, I'll try red loktite under the band. The final thing to try is to drill and tap the heat shield and the barrel just above the two mounting screws on the curve of the front band. This would positively hold the heat shield in place, but it is a last resort. There will not be a problem with any gas pressures from firing. The factory brass bead is drilled through the barrel wall with no problems. I can't move the front heat shield band back to the barrel magazine tube and drill and tap it there. The Big Dot doesn't allow the band, at that point, to clear the muzzle when removing the heat shield. The drill and tap would also retain the simple appearance of the installation.
I won't get a chance to fire the gun for about two weeks or so.
Drill and tap here on both sides.
View attachment 15912
I had a chance to fire the Shockwave with the heat shield today. The heat shield did not move at all. I fired 15 rounds of slugs and then 5 rounds of Federal 4 Buck (27 pellets) within just a few minutes. Again, the heat shield did not move. Not even a little bit. I used a coating of blue loktite under the front mounting band of the heat shield and tightened the mounting screws very tightly. The shield was just a little warm after the 20 rounds and the barrel was hot. I had fired a few rounds of 00 buck and 4 buck just before when I patterned the rounds. I'll post some photos in a day or so.
For $30+ I might order one.