By replacing the .51 ohm with a 2 ohm, it should do the job.
The 317 will heat up to some extent. If it becomes too hot to keep your finger on it, then you might wish to install a dropping resistor at the incoming wire (upper left) of your schematic. The resistor and the 317 share the power dissipation.
The dropping resistor also provides a degree of safety (in case something malfunctions in the 317 circuit).
The dropping resistor does not need to be as high as 50 ohms. Notice the voltage differential is not 14 V, but only a few volts, between your power supply and the battery.
Suppose your supply is 19 V. The differential might be 8V for a discharged battery (19-11). And it might be 5V for a charged battery (19-14).
Therefore a suitable value for the dropping resistor could be 15 ohms.
No doubt you will need to do some experimenting.
Its power rating should be sufficient to carry .3A. Maybe a watt or two.