18 gauge is thicker than 20 gauge. 18 gauge is 1.27 mm thick while 20 gauge is .953 mm thick.
12 gauge.
16 gauge pipe is thicker than 19 gauge pipe.
26 gauge is your common metal mailbox 26 gauge is comparable to the skin on an elevator door.
16 gauge is thicker than 18 gauge.
using master vacuum gauge and master pressure gauge
A Bar is not an over under, and what do you mean by tooling master?
A radius gauge takes the guesswork out of designing or duplicating a part, no matter what size. Arc Master Radius Gauges
if its a 12 gauge about 475-550$
Spiegel Inc. It was a Sears brand
100-345 USD
100-350 USD depending on condition
you need to check it against another gauge that is accurate which should be calibrated by a pressure calibration lab. So at least you know that the gauge you use to test your oil gauge is right. Then just "tee" in the "master" gauge into your oil line and check the two gauges against each other when the engine is running.
10-350 USD or so
100 or so
If you already change the unit and it still the same then it can be the oil pump.
Im not sure the year of the model 870. It is a Wing Master 12 ga. Ser# s189445v.