Well, there's a one-word explanation for that - Remington. After the bean-counters and later 'venture capital' people got hold of the company, it has never done a decent job introducing, and crucially post-introduction support for any of its new cartridge designs. Lots of introductions over the years, well until Vista International took it over anyway, but when did Remy last have a real success? Its really successful introductions were many decades ago - 222, 223, 22-250, 7mm Rem Magnum and suchlike. It has been behind the curve on every major shooting trend - short magnums, 6.5s, 'Modern Sporting Rifle' (AR-15 platform) designs. It trails along behind others instead of trailblazing and even when it does, if it's not an instant bestseller, it loses interest and lets it die on the vine. It's produced some excellent designs like the SAUMs, but too late behind Winchester and its pioneering WSMs, and so Remington ended brass production for most (all?) SAUM numbers years ago. Those in the know say the little .30RAR (Remington-AR) cartridge of 2008 for AR-15 type MSRs was a superb little beast, a really good light deer number, but it was a commercial flop, not adopted by anybody else, and is also long discontinued. The 6.8mm Rem SPC too never fulfilled its initial promise despite all the hoopla over it and its US military special-forces parentage and links. The SPC enthusiasts insist that Remington made a complete hash of the chamber throat, leade, and rifling twist-rate issues on 'productionising' the original wildcat models, so much so that there is a non-SAAMI 'SPC II' version used in nearly all target and hunting builds and gives lower chamber pressures and higher MVs. And who in Remington decided to leave the back end of the long-obsolete and low-pressure parent .30 Rem case unchanged so its version of the SPC has a Large Rifle primer with hardly any case-head surrounding it? Hardly surprising that aided and abetted by the chamber problems US military users had lots of over-pressure case related functioning problems in the Middle East summer heat and Remington had to download its factory production ammo pronto resulting in a failure to provide the nominal ballistics. (Hornady did the job properly with its SPC ammo redesigning the case to Small Primer and making the case-head much stronger.)
With Vista International now having sold its Outdoor Products group which includes Remington ammo and components to the successful CSG European conglomerate (The Czechoslovak Group), things might improve, or then again be milked purely as a profit cow, who knows where Remington goes in the future.
