Absolutely incorrect. Perhaps you're thinking of France? Open question whether 130mm is a actually new design or just a scaled up 120mm.
Aside from the obvious success that Benet has had with the M777ER and XM1299 ERCA, the U.S. might have the most genuinely experienced main battle tank gun designers in the world, at least outside of Russia (or including it).
M68 is not an L7 in the slightest. It only shares ammunition, which is not very relevant, as the breech design and recoil system are completely different. Neither is the M256 a Rheinmetall gun, it only shares the caliber, but the gun was designed by Benet. Everything else, again, is different. Maybe it can take the same barrels. Provided they're L/44, of course, because the L/55 becomes both unbalanced and overly heavy when mounted on the M1 tank.
XM360 is an indigenous American tank gun, as is the XM35 (a derivative of the M68A1, with an even stronger breech), and the XM291 series, if we want to dip into the late 1990's and early 2000's. All three are among the most modern tank guns in existence, barring the 2A82 and possibly some experimental Chinese guns, and these have been sustained as the same people who worked on them definitely haven't left Benet (or did so only very recently).
RAVEN is not a tank gun, it's a system, explicitly designed for large caliber recoilless rifles, and has zero relevance to future U.S. tank guns. It was so the Stryker MGS could fire 120mm rounds if I remember right, but it was never particularly successful, because it's a glorified recoilless rifle. You can't really armor those.
The most obvious choice is either XM360E1 or XM291 as a starting point, like how ERCA uses some weird howitzer breech from the '80's.
