Some units do allow it - others do not, or only approve unit-wide modifications provided by that unit.
The US Army's M16 was considered a "light rifle" for jungle warfare in 1963. While troops used the M14 service rifle thru-out the world, only Vietnam used the "light rifle."
No. You don't get to keep any weapons.
"Swiss Miss army rifle
Th XM8 rifle was developed by the US Army from the late 1990s to the early 2000s. It is a lightweight assault rifle. The US Army collaborated with Heckler & Koch to design the XM8 rifle.
The Greene rifle, a bolt action rifle that still used percussion caps and combustible cartridges. It was made during the US Civil War in 1863. It was of VERY limited service, but was the first.
Earned awards can be worn on the service uniform. You will have to consult the appropriate regulations for placement, they are typically going to be lower priority of any Army issued awards.
M14
For that time period, it would've been the M1 Garand, which was also the standard service rifle of the time period.
The Croatian army currently uses the VHS (Višenamjenska Hrvatska Puška), a bullpup assault rifle developed by the Croatian defense industry. The VHS is designed for versatility and compactness, making it suitable for various combat scenarios. It is chambered in 5.56×45mm NATO and has been adopted as the standard service rifle for Croatian armed forces since the early 2010s.
Define "modern rifle". A semi auto rifle was made for the Mexican Army in 1897- The Mondragon.
The SAR-21 is the current standard, but the SAR-80 and SR-88/SR-88A are still not fully phased out of service yet.
You should check into this possibility. Although not a requirement, service members are encouraged to submit a will just in case of their possible death while in military service.