Wait a sec...I thought it stood for "Commission Internationale Permanente", I thought it was similar like SAAMI...I could be wrong.
I don't see that 300 WSM on SAAMI, just looked again, nothing comes up for WSM when I search on there. No worries. I think that Lapua LM is the same as the 375 CheyTac in regards to COAL. I have a 2nd blank I could do that long, but only have the one I plan to use for 375CT and one other. Both will be tactical style. I have 2 x tube style Rem 700 blanks. I do plan to mount at least one of them in an AICS chassis. Seems the 300 PRC or 300 Norma would be possible in that same length. I have shot the 338 LM, it is a powerful cartridge, but I think I can get a better cartridge that uses the same or less powder.
CIP is an acronym for a real organization and they are the euro version of SAAMI.
Where it became slang was when we started using it to describe the length of a magazine. It's also a bit of a whine because that magazine is too short to load 300 grain bullets to their optimal length in 338 Lapua. The standard was set when 250 grain bullets were the norm. 300 grain bullets can be loaded to magazine length, but some of the luster is lost because of the reduced powder capacity.
The original AICS magazines had just 2 different lengths. One each for the 300WM and 338 Lapua. The chassis were not interchangeable. The US military came up with an intermediate length AICS pattern magazine to fit longer 300WM rounds under a R700 in a more traditional stock.
Beyond length, there are different feed lip configurations. The most popular 300PRC AICS magazine is the 338 length with the 300WM feed lips.
Beyond the feed lips, the ribs on the side of the magazine act as case guides. Their depth isn't random. The 300PRC will feed from either a CIP length 300WM or 338 Lapua magazine. A 300RUM or 30 Nosler will feed reliably from just the Lapua mag because the case is another 0.020" in diameter. If you get the itch for improved cases and want to magazine feed, checking here early in the process can save some problems later.
I have a 26 Nosler in a R700 that uses the military length magazine. I had to mill the stiffening rib out of one side to get the rounds to feed without sticking in the magazine. I'd learned my lesson when I did a 7/300wsm throated for 190 grain bullets in a 300wm Ruger American. That rifle uses 300wm length magazines that have the 338 Lapua feed lips and stiffening ribs. Some AICS magazine manufacturers are like Burger King these days, you can have it your way.
The 300wsm is on page 108 of the SAAMI Velocity and Pressure Data.
The 375CT is heading on an inch longer than a 338 Lapua when both are loaded with the most popular contemporary ELR bullets into the neck.
Given similar barrel lengths, pressures, and levels of bullet technology, a 300PRC approximates and slightly exceeds the 338 Lapua. Not enough to matter. There is a significant contingent out there that is fascinated by the 338 Lapua. If that's what it takes to get them involved, great. For years, it was a simple and reliable entry level path to ELR.
A 230 ATip will have about 0.050" jump in a standard 300PRC chamber when loaded to CIP magazine length. The 300 Norma approximates the performance of a 338 Lapua Improved. Historically, the 30 caliber was at a disadvantage to 338 on BC. The velocity for BC tradeoff didn't work for the 30s. The introduction of the ATips changed that.
I'm well stocked on powder. Sometimes wait for bullets. Have product arrival notices and backorders that haven't popped in over a year for brass. I don't remember the last time I saw 215M primers for sale. I do remember that they were $60/1000, thinking the price is steep and I still have over 5000 on hand when I ordered another 5000. I'm shooting those primers now and $60/1000 looks pretty good today. My point is powder isn't the biggest problem.
The R700 has some limitations that may apply to what you're intending to do with it. Many aftermarket actions get past some of them, so there is hope.
For decades, it's magazine length limitations meant death in the marketplace for new rounds that exceeded 2.8" or 3.38" lengths. They can be overcome to some degree, but I'd have the chassis and magazine in hand when I started making changes to the feed port. Conceding the point on using a magazine will also remove the need for feed lips but you want some sort of stop to prevent overfeeding the magazine. I'd start with removing the ADL taint, but that won't always help because of where some chassis place the magazine.
The lug size and tenon diameter are disconcerting to some when they're used with the larger diameter contemporary rounds. I think they're OK if you pay attention but understand that further steps into stupid might hurt. The 0.175" section of brass that projects out of the barrel is the traditional fuse for the system. It's a misconception that the bolt supplies any support to that area. Some of the newer cases don't have external belts anymore, but that area is filled with brass so the fuse might have a higher amperage rating than what it's protecting. With both the barrel and action, use form tools for threading and not a piece of tool steel ground to a point. Stop the treads on the action well ahead of the action screw. Leave reasonable clearance for the bolt on the diameter just ahead of the lugs and don't leave a sharp corner at the lugs at the thread diameter. If I was making my own for the uses you're contemplating, I'd switch to 1.120x20 threads. Maybe 24 tpi. I think Winchester went to 28 tpi on 1" tenon actions for the WSM.
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