M16-M4 Inspection Procedures Part III

The next inspection is the firing pin protrusion test. This is accomplished by inserting the firing pin into the rear of the bolt and holding it in place. Then using the MIN and MAX part of the gage you check that the firing pin DOES touch the firing pin (MIN) and that it does not touch in (MAX). If it touches on max then you replace the firing pin.

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There are two other inspections that need to be conducted. I will post those at a later date as I do not have the gages at this time.

Here is the method for testing the gasrings. In order to get an accurate reading you must have a clean BCG. The best way to do this is to insert the bolt into the bolt carrier with the cam pin. Place the BCG on a flat surface with the bolt face down. If the BCG collapses onto the bolt then your rings are worn. This procedure deviates from that of the TM and I personally feel it is a better method.

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Two other important inspections are the bolt carrier key screws and their staking. In addition you will want to ensure that you have the proper extractor spring and insert. In my example I am depicting a rifle extractor spring and insert. Look carefully and make sure that the spring is complete and hasn't split.

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