Consider the possibility of a Glock multi use gun standard or short frame as it meets your need. Adds - Long slide solid top, long threaded bbl. , 3.5 lb conn., up graded springs , plug with push pins , holster to meet your needs and good night sights , maybe XS sights. A good supply of mags and good cleaning kit. With a longer bbl you will get the most out of the 10mm. With a threaded bbl you can use a suppressor if need be. In a good discrete carry bag/case it would travel nicely. Now consider building this gun from a mod 21
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then if you kept the parts in the kit you would /could switch to 45 acp if needed. The build could be about $530.00 + gun +sights + mags if you do your own work.
Second option is start with a mod 20 add threaded bbl to existing slide for around $150.00 + mags but this was not the gun I would like to build.
Use , hunting , outdoor protection , home protection , good travel gun for short or long trips. Being a Glock cost is not prohibitive and its construction is both light and somewhat water resistant.
The same concept could be had in both 9mm or 40 S&W from fractory long slide models but it limits the hunting aspect of the gun.
The suppressor not listed in the cost it would be an option for those who see a need or just would like to have one.
Reason for Glock ? well its in reach of more people do to cost and no need for expensive machine work.