This used to be a topic of considerable interest 25-years ago, but not so much anymore. I think about everyone accepts the 3913/3914 series are usually very good shooters. The 5900 series...

I rarely saw a 5903/5906 that I could shoot better than 5-6 inches at 25-yards, if you counted ALL of the shots fired in a 5-round group. The guns were notorious (with me shooting, anyway) for throwing flyers.

In tinkering around with stock guns, I found three things usually helped.

1) The fastest ammunition, and the guns seemed to favor the traditional RN shaped bullets, rather than the truncated-cone shape.
2) The best possible trigger. Always helps me with any gun. Watch your sights when you dry fire.
3) Either Hogue aftermarket grips or a Hogue Handall over the regular Delrin grips.

I did not shoot a lot of 147s when monkeying around with the 5900s. They weren’t too popular back then. The guns I experimented with liked the plain 124 gr Remington JHP (not the GS) and as much HS6 powder as you dared use. The Federal Hydrashoks that seemed to work so well in the 3913s didn’t seem to do much for the 5900s.

I was always disappointed by the 5906. It seemed like such a great design, but I never saw anyone do any particularly good shooting with one. The little 3913s were a different story. Given a decent trigger, they shot very well for me. I once shot a 5-round target at 50-feet with Federal 124 gr Hydrashoks that might have been more luck than skill. Nevertheless, I kept the target handy on my desk for a long time, for the sake of “conversation.” It was always viewed with great skepticism, so after a while I took it down - to save listening to various accusations, some of them downright insulting.