Does the Remington 750 autoloader keep the action open on the last shot?

Its the magazine (Clip) Cartridge Follower that keeps the bolt open pard. If you were to take the clip out and fire a round, no, it won't stay open. Hope this helps.

well that is what i see as my problem I shot the gun for first time and just had two in clip. chambered a round and shot bith rounds I figured the action would stay open upon firing the second round. It did not- Gun cycled fine

Make sure it is not a 7600 magazine. The pump magazines work fine but will not lock the bolt open when empty.

It's not a 7600 clip. I have one of those too in same caliber as 750 35 whelen. The 750 has the bolt release button on the left side of clip. I'm going to.the range and shoot the 750. I'm gonna do a cleaning first.

If the bolt will not stay open after the last shot its a mag issue.

The rear of the magazine follower is what holds the bolt open.

When I have had the 7400/750 guns, what was recommended to by by a factory Remington gunsmith was to use a brass chamber brush before taking the rifle out and scrub the chamber well. The factory gunsmith said stick chamber leads to most of the extraction problems.

He also recommend scrubbing chamber after firing and to use full power loads

Just a FYI

Your mag sucks.