What size punch do I need to dissasemble an A1 sight? None of my punches are small enough.

Thanks

dont have anything with a1 sights anymore but im guessing the same size as the gas tube

I haven't tried that, but I will. Thanks.

Quoted: What size punch do I need to dissasemble an A1 sight? None of my punches are small enough. Thanks

For the A1 (or A2) you start with a 1/16" roll pin punch if possible, or a regular 1/16" drift punch will do as well.  I try not to drive the pin all the way out, as it is hard to start back in from scratch.  That is why Brownells also has a 1/16" Starter Punch.
The windage drum should then slide off the windage screw shaft as you withdraw the 1/16" punch.
Behind the drum is its detent and spring.
Then a regular flatblade screwdriver is used to turn the screw out of the aperture peep.
There is a thin flat spring under the aperture which may tend to stick in place until you turn around, then it jumps out and getsd lost.  So be sure you pop this out and save it with the rest of the parts.
I try to never start such disassembly without a spare 1/16" windage drum roll pin and rear aperture spring on-hand.  As if you lose or break one of these old parts, you are tango uniform until you next Brownells Colt parts order arrives.  And yes, I prefer Colt parts, as well trusting Brownells to provide the "real deal," not a knock off that was intended to be made to Mil-Spec, but failed Government inspection and consequently ends-up on the "surplus parts market."  

Very good. Thanks to ColdBlue!

Quoted: dont have anything with a1 sights anymore but im guessing the same size as the gas tube

No, the gas tube is is a 5/64".  Using a smaller punch may result in the punch going through the gas tube roll pin...not a good thing.