how to fix front sight cant? i seen a video where a guy clamps the barrel in a vise with hollowed out wood blocks  near the front sight and uses a mallet  and padded material to move the front sight is this a good idea?

The preferred method is to first drive out the sight pins.

Then brace the barrel on some hard wood blocks and use a mallet to tap the sight over.
It may help to first put some Kroil on the sight pins and around the sight and barrel.  Let soak 24 hours or so.
After the sight is straight, re-cut the pin holes and if necessary, drive in larger pins.
Remember, when drilling new slots in the barrel for the pins, the idea is to cut new slots, NOT drill out the sight.
I've used a small round needle file to file new slots instead of drilling.

do u think this guys idea is harmful

It depends on how canted it is.. I like to remove the pins then move it over then install and drill for larger pins or tapered pins also work... but its important to hold the sight in place after you correct it and while your drilling the new pin holes....

Both of my SAR's have a degree of front sight cant.

I simply obtained RPK windage-adjustable rear sights and with a combination compromise of drifting the front sight and adjusting the windage of the rear sights, wound up with one-half the drift otherwise required of the front sight and a zeroed rifle.  They don't look too bad, either.

I have a Maadi with canted FSB and Gas Block.  I have read the various methods suggested and the issues others have noted.

My questions are: 1.  Can I use dry ice and then warm the FSB and GB to loosen the parts, make the pins easire to remove, and to reposition them?

2.  Wouldn't it be easier to just reposition the barrel in the trunion with the barrell in the proper position.  I wonder if it is possible to just teist the barrel without removing it?  You must maintain the proper head space.  It seems to pull the barrel and have re pressed is the way to go.

Also it seems that my barrel itself is a little bent at the trunion.  It wasn't shipped in a solid box and it looks loke USPS may have loaded weight on top of it and bent the weapon.

Any suggestions would be welcome.

In order:

1.  Dry ice probably won't help much.  People also use heat.  This doesn't seem to help the pins at all and doesn't do that much for the sight base.  The best method is to get the barrel in a firm no bounce-no move set up and use a starter pin punch or a nail set to get the pins moving.  Then use a standard punch to finish removal.
If the barrel is bouncing around or moving the force is dissipated and the pins may deform and jam.  
The rubber hammer is the best method of actually moving the sight base, just don't beat on it until it deforms.

2.  Reposting the barrel can work BUT, often it's just the front sight that's off, not the barrel or the gas block or rear sight block.  In that case, you'd fix the front sight and screw up the rest of the barrel assembly.
Plus, the barrel pin is pressed in REAL TIGHT.  They almost never drive out.  They almost always require a large shop press to get them out.  Usually, trying to hammer one out just screws up the pin and receiver.

Twist the barrel without removing the pin?  Yeah, right........  First, it ain't gonna move, and all you'd do is really screw the rifle up.  Second, HOW are you going to grip the barrel and receiver tight enough without really tearing them up?

If the barrel looks bent, check it by using a straight edge, and by looking down the bore at a vertical line on the wall.  If the barrel is bent, the shadow down the bore will be "broken" and not continuous.
If it looks bent, send it back to whoever you bought it from.

Seriously, the correct fix here is to drive out the pins, bump the sight base over and re-cut the slots in the barrel.  This is actually pretty easy.

Thanks for the advise dfariswheel.

I have a laser line level and placed down the top profile of the AK.  What I discovered is that the barrel is canted to the right, not bent (the barrel is straight), just angles off to the right.  It looks like the Gas Block has tried to stay straight.  The fact that the front sight was pushed furthest to the left it could go should have told me.  I paid a low enough price for it that I figured it wasn't perfect and at $275 I figured the repair price wouldn't be more than $250.

I would like to keep the chromed barrel, but whatever it is, it is.  The CAI monkees assembled it at St. Albans after de-milling it.  It cycles nicely, but can't be sighted in.  I am considering claiming damage on the USPS insurance.

Again, thanks for the help.

Regards

I think the repositioning and repinning idea is a good one, but honestly, I wonder how many rifles have been ruined or generally mucked up in the process.

Canted front sights are common.  The easiest fix is to get a windage-adjustable rear.  A good item to have regardless of the existence of front sight cant.

Get an RPK sight, zero the rifle and see how you like it before you start the other processes.

As far as that goes, are those who do it using a mill machine or drill press setup to drill the next-size-larger FSB pin holes, or a hand drill?  I'm not sure what hardness the FSB is treated to, so I'm curious.  Might be a good idea/necessary to have the FSB anchored with a jig of some sort before drilling?

When drilling new slots in the barrel for the pins, if you're careful you won't need larger pins.

HOW the slots in the barrel are cut, whether with a milling machine, drill press, hand drill, or with a needle file as I've done when power tools weren't available isn't important.

What's important is "keeping your eye on the ball".
This is nothing more than keeping in mind WHAT it is you're trying to do.  Where problems happen is when you're just trying to get a drill through that hole.  What you need to focus on is that what you're trying to do is drill/cut new slots on the BARREL for the pins to fit through.
Pay attention to that and you won't enlarge the front sight base holes or drill off and ruin the base.

Thank you for the good advise.  Without the drilling and re-pinning being done by a good gunsmith with the right tools; and the difficulty in drilling a hold thru a hole would you think a new barrel be the better choice?

No.
Installing a new barrel is a much larger job then correcting a canted front sight.
A new barrel has to be pressed in and that requires some kind of special pressing device or a big shop press, then you have to drill the barrel pin hole which is a good place to screw up a barrel and receiver unless you do it right.
To install a new barrel you also need a set of heads space gauges to set head space.  In the AK, the barrel is pressed in until head space is right, then the barrel pin is drilled and installed.

Also, first you have to find a really new barrel, then there's a chance the new barrel may have canted sights or gas block, which puts you right back where you were.

You're over thinking this.
LOTS of people have gotten Romanian AK's with canted front sights and have fixed them themselves with ordinary home tools.
Really all you need to do it is a short starter pin punch which you make by cutting a Sears punch off to about a 1/2" working length or a nail set, some wood and possibly a buddy to brace and support the barrel, a proper size drill bit, and either a rubber mallet or a block of wood and a hammer.

Installing a new barrel in an AK is a big job requiring more tooling then most home shops have, and possibly more than the average local gunsmith might have unless he works on AK's.
Fixing a canted front sight is really not a major gunsmithing job.

If you're unable or afraid to drill new slots for the pins, consider using tapered pins.

I removed all of the removable parts and discovered the reason the hand guards were so tight.  The barrel was a few degrees off top center to the left when it was reassembled.  The pin way and the slots in the barrel were both off top center.  I also found that the RSB was also off of top center as I can insert feel guages between the RSB and the trunion.  I suspect that when I press out the barrel I will find the correct pin way as well as the slot drilled to reassemble the AK.  It seems that the gas block and the FSB will be properly aligned and no longer canted, or at least not as badly canted,  I will also press out the pins in the RSB and drift it off and realign the RSB and then straighten the barrel.  It seems the barrel leaned to the right when pressed in.  If the pin slots aren't right, then some careful time with a round file will nail it.

The hydraulic press and the bench vise make it much easier.  I welded some round stock together with off set to press out the barrel in the manner illustrated by the LeigionArms web site,   http://www.legionarms.com/pages/Building-Instructions.html

Everything went back together very smoothly.

Thanks