I asked a guy who was a pretty big player in S&Ws LE division about that years ago. Here is what I recall he told me.
When the 4516 no dash was released, there was a problem with tolerance stacking. SOME 4516 no dash pistols would be built to looser tolerances due to wear on tooling and those pistols had issues/malfunctions. S&W had him and some engineers look into the problem.
He took several random, new production 4516s, a few cases of ammo and two helpers and fired the 4516s - till they were too hot to touch. Then they stuck them into pails of water to cool off and shot them some more. He found the guns to be reliable.
But the engineers were running a 4516 no dash, in a ransom rest and recording it firing on high speed cine film. And they thought that the empty shell casings were not travelling far enough - fast enough, from the ejection port, during cycling.
So despite the vigorous defense of the 4516 no dash by my aquaintance and his finding of the tolerance stacking during production, S&W went with the recommendation of the engineers and ended 4516 production at slightly over 5K units and redesigned the pistol. Resulting in the 4516-1.
The 4516-1 had a thicker, heavier slide which changed the timing during cycling. It also got a new single recoil spring instead of the dual nestled springs of the no dash. The magazines were also changed. They got new followers and the feed lips were slightly different. Some early 4516 no dash mags had indentations in them to keep the top round in the mag from moving during recoil - similar, but not the same, as S&W did with the CS45 mags later on. Those indentations were eliminated in the 4516-1 mags. IIRC, there was a slight contour change in the feed lips as well.........or in the spacing between them....
And the early production 4516-1 mags also got the legalese "warning" etched on them to "ONLY USE IN 4516-1". Ironically, according to my aquaintance, S&W had MORE issues with the redesigned 4516-1 then they did with the no dash pistols. Which caused them to modify the guns sent in for warranty work to the old dual nestled recoil spring set up and place a bushing in the end of the spring tunnel of the dustcover.
Eventually, it was decided at S&W that the recoil system and NOT the magazines were responsible for the 4516-1s issues. So the etching of magazines was dropped. And later another new follower, the black followers, were made to be used in every version of the 7 round single stack 45 mags.
I have owned every variant of the 4516 made with the exception of the prototype. And I still own a 4516 no dash and a LE Special order "4516 dash 3". The dash 3 being a 4516-2 made after the official end of production, featuring laser etched markings on the slide and frame. I have used all the various 7 round magazines in all the different 4516 variants. And I still use my "USE ONLY IN 4516-1" magazines, with the red followers and yellow followers as range magazines with no issues. None.
As a matter of fact, several years ago I purchased a LNIB 4516 no dash and ran a "test" of the pistol. Over several years. Recording any malfunctions I experienced. And I shot that gun a lot. And let new shooters shoot it too. With all the different magazines made. And I found the stories about the 4516 no dash being problematic, to be unfounded.
IIRC, thats how I met my aquaintance from S&W. He read my thread. And PMd me the back story. Hope this helps. Regards 18DAI
