How much undersize should neck be on 6.5CM from ballet dia

[Steve Steven]

I am in process of converting .243 Win brass to 6.5 Creedmoor brass, conversion has gone well except for one brand (PPU) of cases that had too-thick necks. (see http://castboolits.gunloads.com/showthread.php?308648-6-5-Creedmoor-from-243-brass )

The neck tension seems to be very high, what should the neck ID be? I measured the neck ID on the reformed cases to be around .260, is that too tight? I had to pull a bullet (no powder!) and it took 4 hard hits on an anvil to break the bullet out.

Thanks in advance for your help.

Steve

[tankgunner59]

I made the conversion from 243 to 6.5 CM. I didn't have any PPU, but I just checked the inside neck diameters on my conversions and some of my caliber specific cases. The conversions ran .260, the caliber specific ran .260 to .261.
Did you bell the case mouths prior to loading? I would suggest you check the unloaded cases in your chamber, if the bolt closes then seat a bullet to the OAL and chamber it. If both of them chamber fairly easily I would load a few cartridges with the start load weight and go to the range to test them.
If you check the thread you linked to I stated there in a post that I loaded 22 and fire formed 20 of those with no problems, two wouldn't chamber completely. I'm actually going to work my load up since these were loaded to start load weights and they were definitely not the velocity I want.

[dtknowles]

I don't load 6.5mm but I suggest an expander that matches bullet diameter. With the expected spring back you get good neck tension without too much squeeze on the bullet. If you are using annealed brass maybe you need an expander that is a thou under bullet diameter. If you are loading for an autoloader you need to crimp.

Tim

[Steve Steven]

Well, I loaded up 10 of the PPU cases, 8 out of 10 exceeded the SAAMI minimum neck diameter (.295") so I trimmed them to .290-.292 to be sure they would chamber. Beginning to wish I had trashed the PPU cases, I didn't have that many and they have caused me a lot of grief. Next stop is the range!

Steve

[1hole]

I suggest an expander that matches bullet diameter. With the expected spring back you get good neck tension without too much squeeze on the bullet.

True. Necks only expand about a thou before the brass stretches passed its elastic limits and what's left is where the actual bullet grip comes in. Any neck squeezed smaller than about 1 thou under the expander/bullet diameter only expands the neck to about 1 thou smaller than the "expander", be it expanded by a die or seated bullet, and that's it.

Squeezing a neck smaller only increases the seating/expanding effort without adding any more to the neck grip. It's easy to convience ourselves that we've added "grip" when we've only expanded the neck bore.