DeBee may very well be right about the 243 ... it was certainly the hardest caliber that I have done to get to feed well (out of the 243, 308, 22-250, 300WinMag). That being said, I wouldn't trade my .243 (that I built on a Turkish action (didn't cut it down) with a Rem700 takeoff barrel) for anything ... it's a tack driver and is VERY pleasant to shoot. The 6mm might be an easier option, I didn't even consider it ... and you could probably even make it on a 243 takeoff barrel. The 6mm usually gives an additional 50 or 100 fps over the .243 ... but the ammo might be a tad harder to find on a shelf if you needed some.
If you are asking about cutting the action down, I'd have to ask WHY? You can make the 243 work fine on the standard length action and if you cut the action, then, unless I'm missing something obvious, you have to cut the bolt down and re-heat treat the whole mess after you weld it back together ... if you don't heat treat, then it seems that you would be writing off the third lug ... which is really what makes this action so much safer than most ... the third lug handles the worst case scenario of catching a rearward travelling bolt much more gracefully than your forehead would
If you want to save three ounces, then I'd go after some of the wood or plastic on the stock ... if you want to have a faster follow-up shot, then I'd make that 243 on a Garand action
Good luck ... these Mausers can be a TON of fun!
Saands