Full Length or Neck Only; What's Best Resizing for Accuracy?

[okie man]

Ok , now that the chest beating and tool comparison is over. Back to the original ? Neck sizing or full length sizing. Each has pro's and cons. Both methods work. I think one should evaluate what is important, reliable function, good accuracy, good case life . Do you have the time, money, equipment and need for neck turning, annealing. Filling cases with water and weighing them. Do you want to size the body, then the neck then expand in one die or 3 ?
After you've spent the time to get your cases how you want them what's next? Do you want to start sorting bullets? Base to ogive, base to tip measurement. Weight sort into groups ?
Then there's powder charges. How close do you make them? Will a standard dispenser and beam scale work or do you need to use an Auto charge/charge master electronic weighing down to the kernel?
I think most see where this is going! I've been loading my own ammo for 25 years or so. 2 years ago I bought my first electric multi function case prep tool. 3 years ago I bought my first bullet and headspace comparator set. I just got my electronic powder dispenser/scale this Christmas. I'm just now thinking about getting a hand priming tool.
Does this mean my ammo isn't accurate. No. Could it be better! Yes , but not much!
I feel I'm at the point to where I'd have to invest lots of money and time for very small gains. Very small! I'm loading ammo with single digit es, loaded rounds all weigh with in a few grains of each other, I get consistent 1/2 moa groups with factory guns ! Most importantly I'm still having fun and enjoying my hobby very much! Isn't that what's most important?

 

[TOM H]

I don't think so.

The head of a rimless bottleneck case is seldom, if ever, centered on the bolt face when the round fires. Extractors often push case bodies off center against the chamber, Their diameters at that point are smaller than the chamber.

But case position is very repeatable from shot to shot. Accuracy is good. A perfectly straight 308 Win cartridge with its head .001" off center in the chamber will put its bullet tip about .0007" off bore center in the opposite direction. The case pivots on its shoulder in the chamber shoulder.

New 308 Winchester cases with a 3/10 grain spread of IMR4895 under Sierra's 155 grain bullets having .003" runout tested 2.7 inches with 20 shots at 600 yards. In the first match with that new bullet in ammo loaded on two Dillon 1050 progressive's, a couple dozen top ranked long range competitors said it shot about 3 inches at 600. I had the high 4 day aggregate score shooting 600, 800, 900 and 1000 yards using metallic sights.

Bart isn't that target your shooting @ 7ft square so what was your score. Better yet picture of your targets.

 

[Swiftkill]

I usually shoot very hot loads, not excessive pressure just fast cartridges pushed to the max that I can get best accuracy. 300 win mag at 3000-3100 fps, 220 swift at 4300 fps, 243 with 58s at 4100 fps, etc. I like Partial sizing with FL dies. Just enough to feel the slightest resistance when closing the bolt I know the cartridge is centered on the shoulder which is a much larger bearing surface and the neck has plenty of room for expansion. I usually dont care about getting rid of brass in 5 or 6 loadings, I'm not cheap about brass and don't want to risk a ruptured case. I wouldn't hesitate to do neck sizing with a bushing, but either you have to use consistent brass or have multiple bushings and/or need to true your necks. I like to shoot. I do enough case prep. I usually get my guns shooting in the .300s by partial sizing.

 

[Bart B]

I like Partial sizing with FL dies. Just enough to feel the slightest resistance when closing the bolt I know the cartridge is centered on the shoulder which is a much larger bearing surface and the neck has plenty of room for expansion.

The case shoulder centers perfectly in the chamber shoulder from firing pin impact before the primer fires. Or before firing if a bolt face ejector pushes it there.

You'll get best accuracy if the bolt freely closes on each round because its head goes into battery exactly the same way for each shot. Otherwise, the barrel won't whip the same way for each shot while bullets go through it.

Difference is only 1/4 MOA or thereabouts. You decide if that's what you want to do.

 

[Bart B]

Bart isn't that target your shooting @ 7ft square so what was your score. Better yet picture of your targets.

1729 out of 1750 possible, as I remember all the way back to 1991.

No, the target is not 7 feet square. Its paper is 6 feet square. Been that size since around 1920.

No target pictures ever taken. Word of mouth has been good enough among NRA's high power rifle discipline's competitors.

 

[bigedp51]

I'm convinced the best accuracy happens when resized case necks are best straight and centered on the case shoulder. That determines how well centered bullets are to the bore axis when fired in cases headspacing on their shoulder.

How many shooters measure "shoulder runout" vs case body and neck runout or concentricity.

And with a rimmed case or belted case with .002 shoulder bump the case shoulder never touches the shoulder of the chamber. And doesn't the Military use the .300 Winchester "belted Magnum" as sniper rifles? When do their shoulders center the bullet in the chamber?

With the cartridge fitting the chamber like a rat turd in a violin case or full length resized the bullet has wiggle room to let the bullet self align in the throat. Meaning the case body has little to no effect on bullet alignment with the axis of the bore.

 

[TOM H]

1729 out of 1750 possible, as I remember all the way back to 1991.

No, the target is not 7 feet square. Its paper is 6 feet square. Been that size since around 1920.

No target pictures ever taken. Word of mouth has been good enough among NRA's high power rifle discipline's competitors.

It's funny but your F-Class team members like David Tubbs has never mention you or coach of that team Mid Thompkins or his wife Nancy who is also F-Class shooter and team coach.
https://bulletin.accurateshooter.com/tag/mid-tompkins/

Hunters don't have luxury of having sighter so normally it's first shot that counts.

 

[bigedp51]

It's funny but your F-Class team members like David Tubbs has never mention you or coach of that team Mid Thompkins or his wife Nancy who is also F-Class shooter and team coach.
https://bulletin.accurateshooter.com/tag/mid-tompkins/

Hunters don't have luxury of having sighter so normally it's first shot that counts.

He is as welcome at accurateshooter.com as F. Guffey on one of his ego trips.

 

[Bart B]

It's funny but your F-Class team members like David Tubbs has never mention you or coach of that team Mid Thompkins or his wife Nancy who is also F-Class shooter and team coach.
https://bulletin.accurateshooter.com/tag/mid-tompkins/

Hunters don't have luxury of having sighter so normally it's first shot that counts.

Sighters are not allowed in some high power matches.

I've never shot an F class match.

 

[Orange Dust]

Im not getting in to all this other than to say loading for a big overbore magnum is very different and more challenging for long range hunting than loading fot a target cartridge. Or, at least it has been for me. Also dont care about aggregates, only cold bore and the next one. Really a different game.

 

[Bart B]

Im not getting in to all this other than to say loading for a big overbore magnum is very different and more challenging for long range hunting than loading fot a target cartridge. Or, at least it has been for me. Also dont care about aggregates, only cold bore and the next one. Really a different game.

That's fine by me.

 

[Bart B]

How many shooters measure "shoulder runout" vs case body and neck runout or concentricity.

It's not shoulder runout, shoulders are fixed in the same place from shot to shot and should be the front reference. Not the case body next to the shoulder whose out of round conditions skew runout numbers. Other than me, probably nobody does this. Especially those designing bullet runout gauges. They're ignorant of the realities of case positions in chambers when fired, or, if they are knowledgeable, they aren't making the connection.

And with a rimmed case or belted case with .002 shoulder bump the case shoulder never touches the shoulder of the chamber.

Depends on chamber dimensions. Minimum headspace on their shoulder that's bumped back up to. 002" let's my belted cases headspaceon chamber shoulders.

And doesn't the Military use the .300 Winchester "belted Magnum" as sniper rifles? When do their shoulders center the bullet in the chamber?

Yes, 300 mags that test about 8" at 600, 15 inches at 1000. I've no idea how their ammo fits their chambers.

With the cartridge fitting the chamber like a rat turd in a violin case or full length resized the bullet has wiggle room to let the bullet self align in the throat. Meaning the case body has little to no effect on bullet alignment with the axis of the bore.

That's not the chamber fit scenario Sierra Bullet's ballistic technician professed. The case body dimensions are such to have total effect on bullet repeatable alignment to the bore axis. The two in-battery case parts touching the chamber before firing are its pressure ring touching one place on the chamber wall and shoulder in the chamber shoulder.

 

[treeman]

Does one method end up with bullets better centered in the bore when fired? If so, why?

I always had problems after several firings when neck sizing only. I have had best luck full length sizing but only pushing shoulders back 2-3 thousandths. Dies need to be matched to chamber so there is not excess sizing of case walls. If you send a die to Forster they will hone the neck to your specifications. Maybe only their dies. Can't remember right off hand but the body can be honed to achieve optimal fit.

 

[Bart B]

I always had problems after several firings when neck sizing only. I have had best luck full length sizing but only pushing shoulders back 2-3 thousandths. Dies need to be matched to chamber so there is not excess sizing of case walls. If you send a die to Forster they will hone the neck to your specifications. Maybe only their dies. Can't remember right off hand but the body can be honed to achieve optimal fit.

Don't dies have to be smaller than chambers? If their dimensions match the chamber, they cannot size fired case dimensions smaller.

Rimless bottleneck full length sizing die headspace, for example. They're typically. 004" to .005" less than the cartridge GO headspace gauge. Measure your die's headspace to see what it is.