How to straighten a tank gun barrel

Chrisk, I suggest starting out by contacting Tamiya America. They may very possibly replace the barrel for you for free. If that doesn't work, you can try using some heat and gently reshape it. I have had success with this technique with a warped plastic shovel handle. I held it above a candle and gradually straightened it. But you have to be really careful. There's not a lot of difference between the heat to make the plastic pliable and melting it! Hold the barrel way above the heat and give it some time to heat up the barrel gradually.

Barrett

If it merely has a slight bend, you could put it down in some hot water to slightly soften the plastic and straighten it out, holding it straight until it cools again.

It has a slight 3 dimensional bend.  The tricky part would be to use something as a frame of reference so that the end result will be relatively straight from all angles.  

Try heating it using a hair dryer. That might work, but if it's a compound bend (like an "S") you might need to replace it with another.

Is it hollow?  Could you find a piece of rigid wire or rod to place inside of the barrel?  That might keep it stable and straight while it cools.  (I've never done this, I'm just thinking out loud)

I second BigJim's suggestion for hot water.  

CN Spots

Is it hollow?  Could you find a piece of rigid wire or rod to place inside of the barrel?  That might keep it stable and straight while it cools.  (I've never done this, I'm just thinking out loud)

I second BigJim's suggestion for hot water.  

That's what I'm thinking of.  Heat the barrel, insert a straight rod and cool it.  I need to find a rigid rod and cut it to match the barrel length.  I don't have such a rod at home and don't know what to use (maybe, a brass rod?).

Maybe an old metal coat hanger cut to length?

regards,

Jack

But you'll need an insert that is pretty much the identical diameter to the barrel's cavity if you want to take out all the warp. I still think you should start by contacting Tamiya America. 800-826-4922. They are very accommodating.

Here's how I do a composite, It ain't that hard - I've done it before.

Since the barrel isn't tapered, measure the kit diameter/length and use a piece of aluminum tubing. Assemble the original kit barrel and deal with the seams on the brake then use a razor saw to carefully cut the kit muzzle away from the kit barrel right behind the features . Insert a short smaller piece of tubing in each end of the new barrel and insert one end into the mantlet and the other into the re-worked muzzle assembly.

Try a piece of wooden dowel.  Cheap, readily available, and comes in different diameters. Chop sticks, kabob skewers, etc.

I managed to straighten the barrel. I put it down in hot water for 30 seconds and exerted pressure using 12 clothespins, from the muzzle to the base. The barrel looks straight to my old eyes!!