cknight98,
From what I understand Winchester shortened their M70 short action to accommodate the shorter WSSM cartridge. All I know is it's shorter than the M70 Coyote in .300 WSM that my brother in-laws wife has. So far I've run a just under 500 rounds thru my new toy(that's what my wife calls it). Still playing around with load development and things are going somewhat slower than I would like. Between job constraints, clients and taking care of the home front while the wife is going thru rehab getting the time to work with the .223 WSSM is hard to find. What I need is more hours in the day. Another shooter that also has a .223 WSSM is doing much more work on load development. He has more than double the rounds fired thru his than I do. He also reports no signs of excessive throat erosion. If the data for the .243 WSSM is anything like what we are finding out then I would say that Winchester has another winner with the WSSM line of cartridges. The hardest part about owning one, at least for me, is getting used to those little short cartridges. I'm used to handling Weatherby Magnums. My granddaughter is wanting grandpa to build her a south paw .243 WSSM. Reason is because "It's so cute". Lawdog