A nicer trigger pull may help you shoot more accurately but trigger pulls, both good and bad, have little to do with the intrinsic accuracy of any firearm.
True. What I think made the 686 no-dash so intrinsically accurate wasn't the action, but headspace, b/c gap, cylinder chamber throat milling, timing (chamber-to-bore lockup).
A revolver is made up of tolerances. One wouldn't think b/c gap would affect accuracy, but I recall an article years ago that indicated the perfect gap was .006. On S&W revolvers, such as the Model 66, the tolerance was .004 -.009. Anything within that was fine. I recall one of my revolvers had a whopping .013. I sent it back to S&W and they moved the cylinder forward so that it measured .006. But then the headspace became excessive! You can't just move the cylinder forward without screwing up the other end! (It's like cutting off three feet of a bed sheet and sewing it onto the other end to make it longer!)
Those were the dark days of Bangor Punta. But when the 686 came out, S&W shrunk their tolerances. And it resulted in a much better revolver. I never saw sloppy construction. I learned of a couple of cops who had 681s that not only were inaccurate, the front sights were being rubbed down by their holsters. Turns out that somebody wasn't watching the heat treat. The specs were dead on accurate with the headspace, b/c gap and such. The steel was just soft and the bullets and holsters were taking their toll. S&W sent them back two new guns that were like match grade accurate.
What are the tolerances now? I don't know. But I know the tolerances on the Rugers have never been as good as the early S&W 686s. Usually, the Rugers will be very accurate with the 158-gr JHPs, but with the 125-gr and lighter JHPs not so much. But cranked into Ransom rests, the S&Ws were almost always more accurate than Rugers. Again, things may have changed today, where computers may play a part in the production cycle --- I don't know.
Back in the late 70s, a fellow on the NRA tech staff showed me how to drop a 125gr JHP into each of the chambers on a .357. Optimally, the bullet should catch in each chamber (don't push them through!). A well-fitted chamber should not let the bullet drop through, he said. For self defense, it's not that much of an issue, but if you compete, you may want to note the chambers and avoid them when accuracy is crucial.
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