A few random thoughts here...
First and foremost, this is just me thinking out loud, and trying to light a fire under CanAm.
I absolutely do not work for or speak for CanadaAmmo. Yet...
So I am most certainly not discussing funding.
What started as a note to Chris (probably could have made it a PM...) has morphed into an exchange of ideas, which is great.
But the cartoon of the Homer-mobile has a lot of truth to it.
It is easy to let a project get out of hand.
As I see it, the simpler, the batter.
Certainly sooner, and cheaper.
There are several ways to produce a receiver, some practical, some not so much.
--Old school forgings like old bolt actions are very expensive to set up. So a deal breaker.
--Stampings are also very expensive to set up, but cheap to hammer out large numbers. Not viable for this project.
--Machined aluminum receivers are more expensive than stampings in large numbers, but FAR cheaper in small numbers.
--Extruded receivers combined with machining like the MagPul Masada / Bushmaster ACR could be the best option.
I mentioned using a standard AR-15 barrel with a beefier barrel extension, as the AR-15 spec design is prone to cracking when using a larger case.
https://www.google.ca/search?q=ar-1..._FrJLXAhVJrVQKHeWtDqMQsAQIMA&biw=1252&bih=604
A beefier bolt head and matching barrel extension means that cartridges up to .450 Bushmaster could be used.
It also eliminates the issue that Condomboy raised.
That just leaves it open to a guy throwing a 7.5" AR barrel on it and now it's restricted, technically prohib, so they would have to be complete guns if you're going to use AR barrels etc
Regarding various cartridge choices, and families of cartridges, I have pondered using different magwell adapters and such.
(In fact, that is why I have followed the DT-MDR so closely, as I had considered a similar idea years ago, but did nothing with...)
However, in reality, I would rather keep it simple and see it happen, rather than dream about the "perfect" gun never built.
As far as a new 180B, that could be viable, if it was done well.
I have long thought that the AR-180B is a clever design done very poorly.
To be blunt, the common version is a pile of poo. (I have heard the Sterling version (Made in England many years ago) was quite good.)
If we could get any gun without restrictive laws, it would be a $500 gun at the most.
And yet, it has some clever features.
If it was re-designed from the ground up, it could be a winner.