G’day juststarting,
Loading the Carcano can be n exercise in frustration, owing to a general misunderstanding of the military ammo, design parameters, production tolerances etc. Firstly, take Wiki with a grain of salt. The original M91 Carcano projectile was always .265 (6.73), with the later SMI etc projectile being .266 (6.756) diameter, but was OPEN BASED! It was intended to obturate into the rifling, with the firearm having a nominal bore of .257 (6.53) to .259 (6.58) and a groove diameter of .2677 (6.8) to .269 (6.84). In production groove diameter had an upper limit of .272 (6.91) but I have measured 2 larger then this in otherwise good looking bores. The 1950’s Winchester ammo was made to the same specs as the SMI military projectile, open based, and it was one of these that killed Kennedy. The current Hornady projectile, despite what is written on the box and anywhere else, is .267 (6.78), so if your current expander ball is .264, then to get .001 “grip” you should get a .266 (6.76) or .002 (.051) oversize expander for Hornady projectiles. As you are using ex-mil, I would suggest you keep the Lee expander you currently have. Cheers
Interesting. I don’t think keeping the original expander for milsurp bullets will work. I’ll order a couple oversized expanders and see how we go. Will need to measure the original one first to confirm size.
Suggest you stop using “dickheady-pedia” as a reference source.
I actually used the Forgotten Weapons as a reference and Wikipedia as a confirmation. When it comes to these things, I don’t start anything until I get three different confirmations. 
So Lee has confirmed that the expander is in fact .264 diameter. Well! That explains a lot.
Well that seems stupid
Unless they are using the Hornady dies which though still wrong are closer than the Lee dies.
Honestly, I was hunting for carcano dies… Online, militaria expo, Facebook, shops. In the end picked up a bargain on Facebook. In all that time, I have never seen anything other than Lee, whom seem to make all the obsolete calibres.
Lee are pretty good about some things. Like making smaller mandrels perhaps larger if you like. I have had two warranty claims with them and they were excellent to deal with.
On the other hand I suggested a small rifle de priming pin and they were not interested. Thats a do it your self job. Get two they are easy to bust when making them smaller and they are fragile once that small sticking out the end of the die.
I like Lee, I am just puzzled what prompted that choice, but apparently it’s not the only one. For example, Nagant revolver (that I’d like to own at some stage) dies that I looked into, are actually not really and you need like 2-3 sets of Lee dies to assemble one. Anyway… happens, learning experience, I am just puzzled that nobody is hitting that snag - meaning using wrong bullets.
It seems it is a bit the same with 303 bullets. The Hornady say they are 3.11 but measured are 3.10 then there are the Sierras that are 3.12 and the Woodleigh that are 3.11 So the neck tension changes a lot depending on the bullet and one is going to shoot a lot better than the other that will not be the optimum size for your barrel.
The head-spacing is another example of Mil spec. If I read mil spec it means stay away it is just good enough.
At our Rifle club we have a bloke that worked at the ADI factory as a Quality Control/ Assurance type guy and he tells stories of how the powder was mixed and near enough was good enough for the military. but for hand loaders they had to take extra steps to ensure each batch was much more consistent burn rates from batch to batch.
Now it may sound stupid and without seeing the Lee expander BUT could you swap it out for the Hornady expander?
I know it doesn’t solve the problem but it gets you closer to the .268 that you need.
Only a thought.
I’m not in a hurry. Will order a couple of expanders.
Quick update on Carcano, thanks @1Fatman
http://personal.stevens.edu/~gliberat/carcano/ammo/reload.html
Lee dies:
- The included shell holder #2 is far too large for the smaller Carcano base. It is absolutely intolerable that a reloading equipment manufacturer should propose the same shell holder for cartridges as dimensionally different at their base and rim as a 8x57IS and a 6.5x52 Carcano. This results, not infrequently, in torn-off base rims. Use a RCBS shell holder instead!
- The seating die bullet hole is designed for undersized and unsuitable 6.70mm (.264") bullets. When one tries to seat the truly fitting and adequate Carcano bullets (e.g., 6.75-6.77mm, as made by Moloc), they jam in the seating die. Another annoying quirk. However, Lee can, on special order, custom size the seating die to suit.
Both bullet points are spot on. So have something to go by now.
Linking related post from elsewhere on the forum:
Quick update. Just extracted the case and checked the expander diameter… 0.262" Not cool Lee.
Damn, no wonder you are having issues. Have you ordered the correct size expander from Lee yet?
Just about to.
Don’t forget to get the correct shell holder