[possenti]

I'm working on a friend's Remington 7400 - .30-06 semi-auto. It's doing something weird...

I load a single round into the rifle with the magazine inserted. I fire. The bolt recoils, locks rearward (last shot hold open). The empty casing is still in the chamber. I click the bolt release on the magazine, the bolt goes forward into battery. I manually pull the bolt back sharply (as if chambering another round), and the empty case ejects. BTW - I'm not "riding" the bolt closed on the live round when I initially chamber. It closes with enough force for the extractor to grab the rim.

This happens every time. The empty never extracts/ejects when the gun is fired, but comes out easily when the bolt is dropped back on it and manually opened again. The spring-loaded ejector seems to have the proper tension on it to throw the empty out. The extractor is not the "claw-type" that I'm used to seeing in most guns. It looks like a rounded snap ring near the bolt face that grabs about half of the case head.
Does it need to be replaced? That's my guess...

[artherd]

Extractor worn or dirty perhaps.

I've had the opposite problem with my 7400, that of occational STUCK cases (that still wouldn't clear with manual cycling of the op-rod.) However, my gun's op-rod was cracked, I am waiting on repair.

One other option, chamber very dirty or burred. Combustion pressure should press the cartridge's walls against the chamber, making it immobile for a millisecond or three. It's possibly the cartridge is staying 'pressure-stuck' a hair too long.

What ammo? Mine dosen't like cheap stuff (except Korean mil-surp.)

[4 eyed six shooter]

I would clean the chamber first. This is where many of the extraction problems are on this rifle.
Good shooting, John K