Possible Breech Load Hybrid. Quick change burst discs?

[Tango71]

This is in relation to my previous post in the combustion cannon discussion. To sum it up, I have to build a cannon for a tank, yes you read that right...A scaled down M4 Sherman tank. It will be made of Sched 40 to 80 DOM tubing and will be all welded together. Fuel will be Oxy/MAPP or Oxy/Propane (undecided yet) Barrel diameter is 1 1/8" with projectiles shaped from pieces of wooden poplar dowel. Goal is to be fairly accurate to 100 yards and be able to blow holes through 1/2" plywood with ease.

After playing with HGDT I have determined that I cannot get the performance I need out of a simple combustion cannon and will have to go to a hybrid. One of the things I'd like to know is if anyone has come up with a good way to change burst disc very quickly in a breach loading type cannon? I have everything else other than burst discs and fuel figured out so maybe you guys can help? I keep hearing all this talk about pistons too. I included a screen shot from HGDT to show you guys where I'm at performance wise. Original muzzle velocity was higher with a 1oz projectile but I'm predicting I'll be well over that so I entered 1.5 to be on the safe side. My limitation is the barrel length (cant be too long it will be too front heavy) and diameter (1 1/8" dowels are the largest I can find locally and cheapest when you factor in best performance per buck)

Any and all help is welcome. Please factor in that I have no access to a lathe but am very very very good at making things work and improvising. I also included a pic of the tank it will be going in to, to show you guys that I'm pretty serious and passionate about this but its not something I've done before so I will need some of you to perhaps walk me through some of the steps so I can build a fun and safe cannon.

[Brian the brain]

I think you'd be better off using a pneumatic cannon or a piston hybrid.
No need for burst discs..

[Tango71]

I need it to be coaxial and breech loaded so a piston may be out of the question.

[Brian the brain]

A Tee section would solve that.

[Gleedaniel13]

I need it to be coaxial and breech loaded so a piston may be out of the question.

I think it is just a matter of selection the high quality piston that will work awesome. I know a lot of users there can recommend us the best quality piston.

[mark.f]

You can breech load the piston with the ammo.

Another thing you can consider is an idea I had for a hybrid to build later this year using disposable "chambers" made from plastic bottles which are breech loaded behind ammo and ignited.

[Fnord]

I think it is just a matter of selection the high quality piston that will work awesome. I know a lot of users there can recommend us the best quality piston.

This is kind of off topic but I am wondering how this guy has flown under the radar for over two years now. He's either an uncanny valley bot or a poor-english spammer for "goshooting".

Can't we restrict signature/website/linking rights until a user has x number of posts to avoid this?
My post here can be deleted if this has been addressed or said changes have already been considered.