how would an RCM feed better inherently, than a wsm?
My 7wsm feeds "inherently" well in my model 70 action.
It's in the details:
I wanted these printed side by side but I got the sizes wrong, Oh well!
You need to study the diameters and remember some of the history regarding the original releases of some of the rifles chambered for these rounds.
Winchester originally started to buy the options to use the ideas from the developments of Rick Jameson who was trying to bring these to market. When Rick asked for payment per cartridge or piece of brass, Winchester dug in their heels and redesigned the cartridges ever so slightly to avoid a patent fight with Rick. They all went to court anyway but Rick being the small fish ran out of money, fame and support, thereby guaranteeing his demise.
Winchester, being the big bully, proceeded to bring the .300 WSM to market but had to rush the rifle development because the ammunition was ready to ship. Many of the first runs of the rifle variations suffered recalls for FEEDING issues. (The WSSM was an even bigger nightmare!) Over time their 'engineers' solved the biggest parts of the problems so the rifles were fit for shooting.
What were the feeding issues?
Look at the drawing. The rim is similar to the standard belted magnum but the body started at 0.555" or 0.023" bigger than the rim, making it a rebated cartridge. The bolt would occasionally override the rim of the cartridge and foul up the feeding. More than that though, the body of the cartridge was significantly bigger in diameter than the standard belted magnum, nothing fit in the standard magazines either so the rails and follower both needed adjusting right along with the feed ramp and magazine box. On top of all of this they chose to use a 35 degree shoulder, increasing the feeding hesitations. It was a balancing act that Winchester had not had to address probably ever so it was a difficulty and an embarrassment for this company.
We don't have these problems now because we have WSM actions, boxes and followers to make the job simple. Then it was a battle of conversions.
Ruger/Hornady on the other hand, chose to avoid court for sure with a design that reflected on simpler thinking, side stepping all the problematic features and just use the basic belted magnum dimensions and skip the belt. 532/532 tapered to 0.515" with a standardized 30 degree shoulder. Juggle the box and follower, Voila!
The greatest drawback to the Ruger design was lack of follow through which is just the way they operate. They make a big splash for a short time then abandon the support so that the cartridge and rifles have to win or lose on their own. That's where the internet comes in, Ruger gets all the airtime it needs and doesn't have to pay out a penny because the internet bloggers and so-called experts make all the noise needed! That's why Ruger shows more design models for rifles and handguns than any other company. They change names and designs like most folks change their underwear. The same basic premise though is still underlying, build them cheap and sell them for a really high profit margin.
I've build and run both of these cartridges along with all of the other variations including the RSAUM versions. All of them perform with amazing similarities when the caliber is similar. We even started out trying to neck down the 300 RCM for another smaller diameter cartridge like 6.5 ****. Historically, the 6.5 GAP 4-S has won the commercial battle of these cartridges.
In the beginning, the 300 RCM would have been easier to build physically. In the end, Ruger waited too long to get in on the roller coaster and has to settle for an also ran.
Regards.