[Autonomous]

On a new to me, like new 1911 the thumb safety hung up and would not engage after about 150 rounds fired.
I wiggled the safety and hammer at the same time and the safety would engage again but it took more force. After manipulating the safety it is just about back to normal.

What could cause this sort of temporary malfunction? Could it be something as simple as the safety plunger?

 

[fieldgrade]

Lube that plunger. I’ve seen a few awfully dry 1911’s.

Is it the factory safety? Which specific 1911 do you have?

This all translates to “damifiknow"

 

[Autonomous]

The gun is a Springfield Armory Professional, 2013 build in 99% condition.
I took it apart, cleaned and oiled everything before taking it out. All the safety checks were OK after reassembly. (Once I got the sear spring in right...)
The malfunction was sudden, not a case of it getting tighter with use.
I'm not gonna pull it apart tonight as I've had a couple beers sense I got home.

 

[jcc7x7]

Check and see if your plunger tube is loose!

 

[Autonomous]

I did replace the plunger spring assembly this morning and it seemed to help. The OE plunger end was not a good hemisphere. It has flats, facets and ridges. I will inspect it closer tomorrow. I''ll drag out my reliable TRP to give me something to compare the Pro's components too.
Those beers tasted like more so's the smiffin will come later tomorrow. I gotta mow the lot before the rains come in the afternoon.

 

[Autonomous]

Ended up rounding the plunger end with a stone. It seems to be good to go now.

 

[Autonomous]

Took another look and the plunger detent on the thumb safety had hard edges. I chamfered the bottom edge of the detent and now consider the matter resolved.