Many modern car and truck engines use powdered metal connecting rods no problems. Hammers and triggers in an AR should be an easy engineering exercise. Today's technology isn't always just about cheap,many times it's about better. You can usually improve on a given part if cost is not considered but the stock part is usually more than sufficient to get the job done. I have had many military surplus rifles over the years and AR triggers compare very well to any of them.

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