You will not get good results with anything other than real bluing, which is expensive and dangerous.
Use your tank and heater and Parkerize
Temps are hot at 172°F, but will not injure you with a splash. The chemicals are much safer than bluing chemicals as well. The 16oz bottle will last many rifles. You would need a thermometer, motor oil, gloves, degreaser, running water.
This finish will look good, hold up better than bluing, and is not a paint. This is the universal post-war finish for most small
https://www.midwayusa.com/product/1841122455