I wondered if any readers have any experience of the oldish Browning single action blowback semi-automatic pistol known as the Modele 125? It was sold between the 1960s and 1988 with target sights, and was developed from the 1922 model. In particular how do you field strip it? I have the details for the 1922 model, but not the later one with the one-piece slide

I am not exactly which Browning 308 you are talking about.

I think you might be talking about the 1910 380, that had to be modified with target sights, and a longer barrel so it could "earn" enough points to be imported into the USA after one of our Gun Bills was passed.

From memory...
If so it takes down the same way as the original 1910.

With an empty gun.

Remove the magazine and retract the slide and lock it to the rear.

Twist the barrel either to the left or right, I cannot remember. It will twist about 1/4 turn.
Then drop the slide lock and remove the slide from the frame.

To remove the barrel from the slide, again with an empty gun push in ot the frong bushint and rotate it until itcomes out of the slide.
Remove the recoil spring, then lock the slide to the rear and rotate the barrel as described above, then remove the slide from the frame.

Once upon a time I had a Browning 1910.

Of ALL the 380's I have ever shot, and I have shot a bunch, and owned a few others, of them over the years, I still like the Browning 1910 best of all.