I bought a .243 Savage 110 a while back. Thinking it was a short action and not paying much attention. Got home and measured and realized it was a long action that savage just milled out for a short action magazine opening. Didn't matter being I already had a long action stock to use. Decided I'd use that action to make a 300 blackout. Couldn't find a long action .223 bolt head, just short action heads. Figured they'd be the same. Apparently not. They short action has a shorter shank and the lugs are shorter. I lucked out that savage has an adjustable firing pin. Being an older model the firing pin hole was also larger then the new ones. So I bored out the head for the larger firing pin (not the tip but the larger shank), adjusted the pin length for the proper protusion. Also had to mill out a slot on the tail of the head. The bolt body had a tab for alignment that the new ones don't. So any way, if you end up needing a long action .223 bolt head you can use a new style with a little work. Hopefully that helps someone out sometime.