To neck size or full length size???

[Mikecr]

BH, your notion that "there is absolutely no such thing as ONLY bumping the shoulder as implied" seems a risky declaration. Do you think it isn't possible?

You might remember my mentioning of testing loads for 'MyMax'. I always do this, and it's here that I produce 3 cases which I send to JLC. But I never intend to run with loads that produced these.
My intent is to have excellent bump dies made that will not size MY case bodies, and mine do not.
Jim wouldn't know this, as he makes dies to the brass I send him (that's what he knows).

I get his dies because I consider them the best, AND the best deal out there.
But I don't use bushings in his dies.
I neck size with Wilson inline dies, and expand necks with Sinclair expander mandrels.

Pulling the firing pin to check fireformed baseline for bump is as useful regardless of dies used to bump(FL or NS, or BUMP). I must be missing your meaning there.

 

[Deleted member 46119]

This should provide the best you can get:
Your Loaded OD = .2455
Size to OD = ~.2425
Minus springback = ~.2435
Expand to .2455
Minus springback = ~.2445 (1thou tension)
Expansion is important to drive thickness variance outward(away from seating bullets), and to normalize seating forces to rational and accurate.
-Further lowering of TIR, and tension variance: partial neck sizing instead of full.
-Even further reduction in TIR: inline seater die(hand die) instead of threaded.
-Another reduction in TIR and tension variance: Culling out case thickness variance
-And another reduction in TIR and tension variance: Culling out case thickness variance and then neck turning.
-Final reduction in TIR and tension variance: Tight neck clearance

When you apply most of these actions to every aspect(full body, shoulder & neck) of modern/improved cases(not an 06), put enough barrel steel around the chamber, and test/measure max pressure growth to this plan, then you make and maintain straight ammo with consistent neck tension and bullet grip -without continual annealing and trimming, etc. Things just get a lot easier.

But it doesn't happen without understanding and a plan. And barring luck(ok, serious luck with RCBS), it usually takes a custom chamber and/or custom dies. Many around here have already spent money beyond this, but don't have it.. They're still headed for step #1: Understanding

Very nice explanation.

I wish you had included that way back.

I live for data and engineering details. Now I agree with FL vs. NS but you have to do all this homework to make it work.

 

[Pdvdh]

Very nice explanation.

I wish you had included that way back.

I live for data and engineering details. Now I agree with FL vs. NS but you have to do all this homework to make it work.

Yeah, I've read Mike's post several times, and I now think I understand his theory and implementation. This is bit more than I do with even my most meticulous reloading, but I still like to understand the theory and mechanics one would employ to achieve lowest TIR and most uniform neck tension. Mike stress's the value of uniform neck tension above and beyond TIR. Since I don't have a tool to measure it (I think he does), I likely fail to fully appreciate its role in minimizing ES and improving accuracy.

 

[Mikecr]

I do consider tension as very important. Not just neck tension, but chambered body tensions as well.

Let me clarify my context of 'tension':
We often refer to bullet interference fit as tension,
We might consider seating force as indication of tension,
A few could consider neck tension as that caused by runout of a chambered cartridge,
So the term is pretty broad, but chosen context can hold well enough for subject discussions.
Much like 'annealing'. It's just easier to say annealing, while we really maintain a context of process annealing(stress relieving) -rather than full annealing.

I use 'tension' broadly, but this is what I'm generalizing in it;

A force to overcome on releasing a bullet is GRIP.
A force to overcome on seating a bullet is FRICTION.
A force that comes to new balance on firing is TENSION.

Bullet Grip = Neck Springback
No matter how much interference fit, or how much friction you provide to a seating bullet, grip is still just neck springback from last yielded to dimension over the area applied. It's a variance,, it's limited in adjustment,, but it can have an affect to tune, especially when best seated distance is off the lands, or when you're relying on an underbore cartridge at a very high pressure node(fast powders).
Consistent grip = management of springback

Seating Force = Friction(Kinetic)
Resultant friction coefficients of the bullet jacket and inner neck, and the force provided by neck tensile strength from the area of interference.
Seating force is not a direct indicator of resultant bullet grip and can be deceiving as applied(if not careful). A fully annealed neck, unexpanded, and squeaky clean inside, can provide seating with ~normal force, yet it has little springback to grip a bullet.
Variance in seating force causes changes in seating depths due to varied wedging of seater stems on bullet ogives.
Consistent seating depths = management of friction

Tension = perpendicular preloadings of chambered cartridges
When you chamber a banana, you preload it in abstract ways. On firing, the banana straightens but where is the bullet and where is it pointing while this is happening? Will this happen the same shot to shot?
This is where TIR comes in for tighter chambers, while more forgiven with looser chambers.
Why not just go with loose chambers then?
Loose chambers mean greater brass yielding to larger diameters, which means less recovery from thinner brass, leading to difficult extraction unless sized more, to cause more yielding and work hardening, which changes springback, which changes case capacities with each reloading/trimming cycle, varying peak pressure curves, leading to more load tweaking, so more trips to the range, where Mrs.Jones frequents her teasing, and your wondering interest causes confrontation with Mr.Jones...
Don't go to jail with Mr.Jones...
Stop paying too much for loose chambers.

Run with the tightest chamber you can manage, given qualifiers, and make straighter ammo for it(the two go hand in hand).

I do measure seating forces of my necks, while pre-expanding with an instrumented mandrel. Because I manage springback and friction really well, my grip can be inferred from seating force. But I'm not actually measuring grip, and I'm not aware of any tool to do this today. There is about 30% of one in my garage that I need to finish some day..
I need to get off the internet someday..

 

[Pdvdh]

I don't believe I experienced the 0.001" case neck springback on my cases. If I recall correctly my sized necks - minus the expander ball - were measuring between 0.2435 to 0.244". However I don't own a tool to accurately measure the neck ID down inside the Forster die. I'm just trusting Forster ground it to the diameter marked on the die - 0.2435". I'll be resizing 1000 or more additional cases soon, so I'll make a point to measure some more neck-sized ODs out of curiosity and for comparison to your 0.001" rule of thumb.

I've measured several resized case neck ODs, sized in the Forster die without the neck expander button. I'm reading ~0.243 to maybe 0.24375 on the resized case necks. The fired case necks were ~0.254" prior to resizing. The Forster die is stamped with a case neck ID dimension of 0.2435". I have no tool to measure that dimension. If it is honed to an ID of 0.2435", I'm not experiencing much post-compression rebound on these .223 case necks. .223 is a shorter case length and smaller diameter than most, so both would mean lesser spring back, in my mind.

I found it interesting to note that the case neck ODs on individual resized case necks varied close to 0.00075" on my dial calipers as I rotated the case neck in the calipers. This leads me to believe that case necks that haven't been turned to uniform neck wall thickness expand and rebound slightly differently at differing locations, due to uneven neck thickness and therefore differing elasticity. I think the larger resized case neck OD is likely being measured where the case neck wall thickness is greater, and the lower OD is being measured at locations where the case neck thickness is thinner. Perhaps another benefit of case neck turning for those that seek the ultimate consistency in case neck tension?

These .223 Rem cases were once fired R-P factory cartridges.

 

[USCGLongBow]

I neck size all my rifles. Straight-wall cases like pistols should be full length sized, for ease of feeding. I have heard the Full length size for hunting, but the only time I have had issues with reloads on a hunt was when I didn't seat the bullet deep enough for that particular rifle. I shoot bolts and AR rifles and follow the same procedure for all of them and have yet to have a feed issue.