[Rapier]

Jack,
It is not a compressed charge and the OAL, as measured with a caliper, was exactly the same measurment as the dummy case. The powder charge goes just below the bottom of the neck. The bullet base is within the neck. All this was already taken into consideration prior to writing the post.

If the headspace in this case had actually started on the belt and stayed on the belt, the bullet in the fire formed and neck sized case would not have contacted the lands, because the belt did not move. Plus, a belt to base measurment does not shrink, it grows, which would not extend the bullet in the OAL series of measurments when the OAL remains the same, the bullet ojive would be moved back as the base to headspace meaurment extends. The base to headspace measurment had to shrink to allow the bullet to go forward. After 50 years reloading, decades of building custom rifles and having owned several hundred belted case guns, I am more than framiliar with how they are "supposed" to headspace.

The only part of the case that could move and cause the bullet to go forward, after neck sizing, was the shoulder. What I conclude occoured is that the previously fired case, in another chamber, did not actually resize with just the die use, to properly fit my gun's chamber and that the resized case was just barely over length at the shoulder and had a crush fit. When it was fired in my chamber it actually shortened due to rebound and then allowed the case to properly headspace in my chamber, which then created a situation where the reload's OAL (which was exactly the same as prior to firing) now had a chamber fit that allowed the bullet to go forward just enough to contact the lands.

I solved the problem by resetting the OAL after fireforming, please read the post. This was not written to get advice, it was written to give you guys a heads up when you start a reloading process based on a once fired case from another gun. Fireformed in your rifle, the case might just change the way the case fits within your chamber in such a manner that the reloaded round could become unsafe, very rare, but I now think possible.

The post boils down to this: Simply check the finished product in your chamber before you shoot the reload after you fireform it. Easy fix, just check it.

I have never, to my knowledge, seen this happen before and believe the occurance to be worth a mention and a caution, once I discovered it to have happened. You have been advised and warned so do as you wish.
Ed