The M380 specs out at 16 oz, and the LCR 9mm at 17.2. Do you feel the difference in the hand? How thick are the cylinder walls?
Also, the SAAMI pressure spec for 9x19 is 35,000 psi, and .357 magnum is listed as the same, at least according the LASC website. Of course, .380 is only 21,500.