They are both unrestricted rifles so thats a plus, but as one is a centrefire rifle and the other a rimfire this could be used as grounds to demand a new application.

So in short the answer is, no one can say for sure.

I've seen guys getting swaps from a 22lr to a 308 then I've seen guys get refused a substitution from a 243 to a 6.5 rifle.

One thing I will say is, at least in my district, they are tightening up on the requirements for substitutions. So if its not a direct substitution with little to no difference(s) between the current firearm and the one being sought, they are seeking new applications. IOW if its not a (example) 22lr to a 22lr then its a new application.

You can submit a subtitution, or wait for the FO to return to check. If it requires a new application then you've lost €52 worth of license. You could submit a new application and forego any doubt, but as your FO is away and it won't be processed until he returns why not wait to check with him before doing anything.

Well new application or sub it'll be 10 days until he (FO) is backs o nothing happening till then.

My district they will do a sub from rimfire to centrefire so long as the purpose remains the same.

So you want to go from a 22lr rimfire to 223 centrefire, with the 22 currently licenced for target shooting, hunting and pest control and the 223 for the same they will do a sub so long as the game being hunted is the same(ie foxes).

Mind you, they still take 1.5 months to do that sub, so not much faster than a new licence.

Similarly to clivej they won't do a non restricted to restricted or vice versa.

Unfortunately entirely depends on your district.

Talk to your FO and explain the situation that you need the 223 quickly, and they may be able to help, either by putting it through as a sub or expediting a new licence.