I have a new friend. May become a regular buddy.
Last night I finally got to a range with the R 51, and was pleased with it. There were hiccups. The first time I charged it, using a full seven-round mag, the top cartridge hung up on the ramp. Cleared the stoppage, reloaded full mag and used the slide release instead of pulling the slide back, and the pistol functioned perfectly for the next 80 or so rounds.
Those 80 rds included roughly 30 rds of the Browning 115 gr ammo, then a full box of 50 Federal RTP 115 gr. I then started back on the remaining ammo in the Browning box, and had one additional failure to feed, again with the first round of a full magazine. I don't know whether these failures were in the same mag, or not. Last two mag loads worked fine.
Accuracy at 7 yards was 2", so I moved out to 15 yards and stayed in 4" groups except when I clearly goofed up. It was the first time with any pistol in about three months.
I'm happy, and convinced the little Rem is a keeper.