I use good brass, that I've uniformed. I clean and anneal on a routine, and I use good bushing dies. I've done all I'm willing to do to make the brass be the best I feel it needs to be.

I can understand the "want". I enjoy precision, obviously. Ive been getting the last bit of virgin brass fired for the 7 Rem Mag lately. Just doing my daily, off-duty rifle training. A cold bore shot 500 yards or more. The virgin brass is pretty darned consistent shooting, though not as consistent of fired brass. And the fact that I know my shoulders grow .014" from virgin to fired, fired brass makes an amazing 60 fps more.

I was teaching yesterday and i was helping my customer try and hit the little 1 MOA steel at 600 yards. Well, it was a stout, variable north wind yesterday (A gift in August) his 6.5 Creedmoor was left of the targrt, right of the target, back and forth for lots of rounds. We decided to let his barrel cool. He said "I wonder if your 7 Rem Mag can get it done". I said maybe I'll get lucky. Cold bore, 6" plate, at 600 yards. I said "Now that's fun!"

Point being, it takes lots of work at the loading bench to be able to do that. Then it takes paying close attention to external ballistics and watching for repeatability. I've got to start all over again getting DOPE on second loaded brass
By next week, when I will have shot up all that virgin brass, and load back with a .003" shoulder bump. It's supposed to create an additional 60 fps at the muzzle, since that is what it did two years ago on fired brass.

I wasn't going to comment since the BS is getting deep and I'm not wearing my rubber boots. But yes, you can "measure" neck tension. There are multiple methods to measure it. The most common method (and easiest) is figuring out the neck tension in .001" increments. On most of my 6.5mm calibers, you have a loaded round diameter of say, .292", and I size with a .289" bushing, I am putting .003" neck tension on the case. This is simply measured in .001" increments, that's all. It gives you a consistent "number" to size your brass to, and return to the same neck tension on future reloads. If I want more neck tension, then I get a smaller bushing for more neck tension. In this case, I am measuring it in .001" increments. It is measured and will apply more or less neck tension on the bullet if I want to, by going to a smaller or larger bushing. By increasing or decreasing the bushing size, I am getting more or less neck tension. Exactly the ft lbs of force holding the bullet in place- I don't care. What I want is a consistent and repeatable neck tension from round to round. What "specifically" the force needed to pull a bullet from the case is, not sure, but it's not a lot. See my next method...

The method most on here are speaking of is the amount of force needed to remove a bullet from the neck of a loaded round. How much force or energy needed to remove a bullet from a case. This could be accomplished, but you would have to have a gauge on the press when pulling a bullet to measure the amount of force when pulling it out. I have pulled enough bullets with an RCBS collet puller to know there is certainly a difference in tension in pulling certain bullets out of various loaded ammo. When I have pulled bullets on my personal ammo, it does not require much force at all. I keep my neck tensions in check, and know specifically what I want, and load to that figure each time. This keeps my ammo very consistent from lot to lot. I have pulled factory ammo that required A LOT of force to get the bullet out of the case. Why? Virgin brass, crimped case mouth, bullets scratched up during bullet seating from rough case mouths on the brass creating more neck tension between the case mouth and bullet surface, you name it.

If you were to pull bullets on virgin brass and compare pulling bullets on fired brass (that has a carbon build up from being fired), the fired brass with the carbon build up would certainly have an easier force to remove the bullet out of the case. The carbon build up allows a barrier between each surface for the bullet to slide on, or release from. The kinetic friction between the bullet and fired case will allow it to be smoother, requiring less force.

Here's the main point- On virgin brass, there is an element of metal fusion or cold welding happening. This cold welding is between the brass case and copper bullet. What is cold welding- "is a solid-state welding process in which joining takes place without fusion/heating at the interface of the two parts to be welded. Unlike in the fusion-welding processes, no liquid or molten phase is present in the joint.... It was then discovered that two clean, flat surfaces of similar metal would strongly adhere if brought into contact under vacuum.....The reason for this unexpected behavior is that when the atoms in contact are all of the same kind, there is no way for the atoms to “know” that they are in different pieces of copper. When there are other atoms, in the oxides and greases and more complicated thin surface layers of contaminants in between, the atoms “know” when they are not on the same part...."

So, copper is one of the main metals this cold welding happens to. What's brass made out of...? About 70%-80% Copper and the rest zinc and other metals. What's the outside of a bullet made of...? Copper! So, there is certainly an element of cold welding happening on virgin brass. This same process is happening on brass that has been cleaned so hard that the brass case is now back to it's brand new finish. Measuring bullet tension on a loaded round with virgin brass and a copper bullet would certainly have more tension than if you loaded it on a fired case (keeping the measured neck tension the same, by .001" bushings).

A lot of competition shooters would load their ammo days before, and load the bullets long. Right before a shooting match, they would seat the bullets deeper to the proper seating depth. This seating right before the match would help break the cold welding happening on virgin brass. This issue is there, and it is a known problem.

Yeah, I'll go as technical as needed. But dang! I got my rubber boots on now!

In physics, tension, as a transmitted force, as an action-reaction pair of forces, or as a restoring force, is a force and has the units of force measured in newtons (or sometimes pounds-force).

increased temperature should accelerate the process.

Which is what I was saying about the weld that happens in a second, or less. Extreme high heat, extreme shortening of time to complete the process.