Which die should I use?

[Innovative]

Hired Gun,
A "double standard" is necessary if you are comparing apples to airplanes. It just sounds like YOU haven't run into problems when reloading belted cases more that 3 times. Again ... it does happen, but it's very rare to get that many reloadings from belted cases. Belted cases are quite different from non-belted cases due to the limited amount of over travel available for your resizing die.

NOTE: You should NOT be able to feel your handloads squeeze into your chamber! You're on the verge of seeing the "fail to chamber" problem that I'm describing.

ALSO, unlike factory ammo - your belted magnum handloads should ALWAYS headspace on the shoulder (not the belt). This prevents brass stretching that leads to case head separations.

AND, I have seen experienced reloaders (with non-belted cases) that were convinced that they needed to use a FL die to bump the shoulder back - when what they really needed was to resize the "pressure ring" of their case. The reason their FL die worked for them is their resizing die was ALSO resizing their pressure ring for them. This is not always the case ... but it happens.

Too many shooters try benchrest handloading techniques that aren't approprate for hunting ammo. My personal opinion is that neck sizing is strictly for "some" benchrest shooters. Tony Boyer doesn't bother with it, and he's one of the most competitive shooters in the world. The accuracy gain might improve your groups by .002" but it's more likely to cause a "fail to chamber" symptom in a hunting rifle. Benchrest shooters are aware of the "exact" overall fit of their handloads - not just the headspace.

Most rifle cases have a slight taper that is difficult to measure accurately, and non-belted calibers are MUCH easier to resize when you use a FL die properly.

Good Shooting,
Innovative

 

[Hired Gun]

I'm not Abinok but I sure know how to read a mic. When it comes to precision I just don't trust the old digital calipers. These are taken with my 0-1" Starrett micrometer.

Brand new 300 Weatherby brass measure .508" to .509" right above the belts. The belts measure .529"
After the 10 firings with good solid loads they now measure .512" to .513" just over the belts and .533-.534 across the belts. The primer pockets are still holding fine. Most run to the small side of the range and have never seen anything but a Lee Collet die. The ones that go .534 catch on the bottom of the Lee die and make a snap noise when the die pops down over the belts. They still chamber fine even before neck sizing again. As you probably know a Mark 5 has very little cam action compared to a 2 lug action and they still close pretty smooth. It seems my chamber is preventing them from growing any more than that. Is this just a Weatherby, Ruger and Sako thing or are other guns different?

Being these have been redlined a few times during testing and have only been neck sized the worst ones have a very small ripple right above the belt where the brass has flowed. My camera won't show it well enough to see. It's almost like a little fillet right in there tight on the top of the belt. I'm certain this is a bad thing but these brass shoot the best. I can't believe the difference between new brass and these. They just keep getting better. I must have shot 5 back to back 3 shot groups in the 2's. One of the guys I was with shot 2 - 3 shot groups the same size with mine. I only shoot 3 shots as we always go rapid fire and the barrel is too hot if we go 4 shots. I'm certain a 5th shot would do a lot of damage to my barrel. His Remington 700 CDL 300 RUM with factory ammo couldn't get under 1 ½ ".

 

[Hired Gun]

Looks like we were typing at the same time.
Thanks for the reply.
[ QUOTE ]

ALSO, unlike factory ammo - your belted magnum handloads should ALWAYS headspace on the shoulder (not the belt). This prevents brass stretching that leads to case head separations.


[/ QUOTE ]

I have been saying this for years but there is one poster here that just can't seem to get a handle on this. According to your postion in the quotes we are on the same page as how a case should fit in a chamber. There is no double standard as both have tapered shoulders to headspace on. Only a straight walled rimmed case would headspace on the rim.

I still like neck sizing only and have grown very accustomed to a little resistance to closing the bolt on my best brass. What I think would be good is some kind of die that would press the case heads down a pinch to tighten up primers pockets on belted and non-belted cases alike.

 

[abinok]

[ QUOTE ]
After 2 or 3 reloadings, most belted cases measure .513" and sometimes a lot more after being resized with conventional resizing dies. What do yours measure?

[/ QUOTE ]
I can't find a piece of brass here anywhere, and any caliber that measures more than .509" except for the 300wby. This brass is on its 6th firing, and measures .516". The wtby brass still chambers easily. My 7mmSTW has the largest chamber... and is the .509" Ill have a chance to measure for 2 7mmrem guns that have cases headed back today to be loaded sometime this evening.
Sizing in the redding body die trimms .002" off that number for most of the cases im loading... + - .0005" or so.
What does your die return the diameter to?

 

[abinok]

Hired gun,
my experences have been simular to your in some ways. I too have notticed that on some cases the collet die will "snap" over the belt, without any apparent problems. ive also notticed that for the belted cartridges, you can find collet dies with a belt diameter as small as .530, so some brass will "snap" earlier than others. I did nottice that some of my reduced load brass (which has 20+ firings on it) has the tendancy to snap a little too hard... and ive notticed the effects as being a little more runout on these rounds... but then again, its a 90gr XTP, and ive grown to accept a little more on it that my LR loads.

As I mentioned, the redding body die puts a dent in that to some degree. if you ever get the urge to try the body die, give me a hollar first, and you can borrow mine to try.
Additionally... Ive never heard any "great controversy" or double standard on headspacing belted cartridges. I bump the shoulder on everything I shoot... well, almost everything anyway. I burned out my first 300WM barrel with the lee collet die, and it shot great, and for that matter, my current barrel shoots well with neck only sizing as well... but it shoots better with .002" of bump. Maybe it gives everything some room to move around and find that warm and fuzzy spot that it shoots best from... or maybe it just makes room for more magical fairy dust who knows? With the shoulder bumped the way I am doing, there is still .005" on average between the belt and chamber, so I know that after its fireformed (usually with a false shoulder he first time) theres no chance of that belt ever touching steel. I must have missed the guy who thought that headspacing a belted case off the belt was a good idea... because I might have tried to do some "splaining" to that fella too.

 

[Bart B]

Well, here goes my special ingredient into this pot of case sizing dies. You may not like the taste it has, but such is life.

Sierra Bullets has been full-length sizing all their belted and rimless bottleneck cases for accuracy testing since the 1950s. They do this because they get best accuracy this way. A good batch of bullets will shoot in the ones in their test range; they meter, not weigh powder charges, too. And all types of rifles used to test loads for reloading data got best accuracy with full-length sized cases. Their first Ballistics Technician had a saying about what's needed for best accuracy: "The case has to fit the chamber like a turd in a punch bowl." No binding of any kind when the bolt's closed. No neck or partial sizing. Only full-length sizing with the shoulder set back a few thousandths on both rimless and belted bottleneck cases. Belted cases headspacing on the belt and rimless ones on the shoulder.

 

[Hired Gun]

Welcome back Bart,
I thought you were going to leave me hangin on this one. Remember the time you told us about the 1000 yard shooters finding out that new brass was more accurate than fire formed brass? I just can't get my mind around this one. What is the logic of a case laying in the bottom of the "punch bowl" (best) verses the case fitting the "punch bowl" well supported on its shoulder with its payload well centered on the bore. (worst) What am I missing? I'm pretty sure I am not alone on this.

 

[Bart B]

[ QUOTE ]
What is the logic of a case laying in the bottom of the "punch bowl" (best) verses the case fitting the "punch bowl" well supported on its shoulder with its payload well centered on the bore. (worst) What am I missing?

[/ QUOTE ]You, and perhaps most others, may not know where a loaded round fits the chamber both before and when its fired. They don't rest in the chamber bottom. Here's some info that may help you understand what happens to a new case or full-length sized one that's close to new dimensions when it's loaded and fired.

First, when a cartridge is chambered, the back end of a case (new, fired or resized) near the extractor groove is pressed against the chamber wall by the extractor. Mauser style claw extractors press the case straight to the side, sliding extractors like post '64 Model 70 ones in front of a bolt lug press the case to the top and others up and to the side at about a 45 degree angle. This prevents the back end of the case from resting on the chamber bottom. So the back end of the case is never perfectly centered in the back of the chamber when its loaded. The force of gravity ain't as much as the extractor's force pushing the case up off the chamber bottom.

Second, most folks get best accuracy with the bullet touching the lands when the cartridge is chambered. That centers the bullet in the bore. It doesn't matter where the case shoulder is; it may or may not touch the chamber shoulder. As there's no such thing as a perfectly round chamber or case,, there'll be varying amounts of clearance around the front of the case body whether or not its shoulder's touching the chamber shoulder or not.

Third, if the bullet's seated not to touch the lands when the round's chambered, it will float someplace in the throat until the bolt's closed. When the bolt's closed and it has a plunger style ejector, that ejector will push the cartridge forward until it stops against something. Rimless bottleneck cases will stop with their shoulder against the chamber shoulder. The taper of each makes the front of the cartridge center in the chamber. If the bullet's got minimum runout, it's also well centered with the bore axis. Meanwhile the case neck will have some clearance with the chamber neck. If a Mauser style flat ejector is used, the cartridge will be setting someplace between the bolt face and the chamber shoulder.

Fourth, along comes the firing pin and smacks the primer. That energy drives the cartridge forward and it stops against something. A belted bottleneck case will stop when its belt abuts the chamber headspacing belt and its shoulder won't touch anything. As the belt's quite square with the case axis and there's no pressure ring to interfere with the fit, the belted case will align itself quite well centered in the chamber. A rimless case's shoulder will be driven hard against the chamber shoulder centering it there if it's not already there from ejector pressure; usually enough to set the shoulder back a bit due to the 25 to 30 pound force the firing pin spring has that's not all absorbed by the primer. Either way, the bullet's well centered in the bore.

Fifth, gas from the burning powder starts pushing stuff in all directions; the bullet out the case mouth and the case against the chamber walls and bolt face; front part of the body presses hard against the chamber first then the back part 'cause the front part's thinner brass than the back part. The back part stretches back until the case head stops hard against the bolt face. After the bullet's down the barrel pressure drops and the case springs back a bit to smaller diameters and slightly greater headspace.

What's the difference between the above and a neck-only sized case?

First, when chambered, the neck-sized rimless or belted case may slightly bind between the chamber shoulder and bolt face. Its body may touch the chamber wall at different places as there's no such thing as perfectly round cases and chambers and it's larger than a full-length sized case. A belted case not sized all the way to the belt will have its pressure ring in front of the belt contact the chamber headspace belt edge at the chamber body at some point that's not repeatable from shot to shot.

Second, when the neck-sized case is smacked by the firing pin and it's touching the chamber body anywhere, it'll transfer that shock to wherever it touches the chamber, not just the shoulder on a full-length sized case. Those shock waves will go in random directions for each shot using neck-sized cases while the full-length sized one is mainly at the shoulder.

Third, when fired, the neck-sized case walls not already touching the chamber will contact it a bit before a full-length sized case walls do for the same components and barrel. I don't think this matters as much as the pre-firing contact a neck-sized case has with the chamber walls at different points when the firing pin strikes the primer.

The big difference is there's more chances of different and non-repeatable barrel vibrations with a neck-sized case than a full-length sized one because of how the case fits the chamber. The highest scoring off the shoulder rifle shooters in the world have been properly full-length sizing their cases or using new ones for decades. I'm convinced the reason so many folks prefer neck-sized fired cases is three fold. They don't prep new cases properly. They set the shoulder back too far when full-length sizing or don't size belted cases all the way to the belt. They don't test their handloads properly by shooting less than 15 shots per group and often use the smallest group fired as the load's accuracy number. People who regularly shoot more than 15 shot test groups and use the largest groups to indicate accuracy typically end up with more accurate ammo using full-length sized or new cases.

Regardless of what off the shoulder folks get accuracy wise with full-length sized cases, return to battery blocked barreled actions and complete rifles clamped in machine rests have proved over the years that properly full-length sized cases produce the best accuracy. But any case sizing process will sometimes make very small few-shot groups that set records in benchrest. When one compares the size of 20-shot groups, they will usually be surprised at what properly prepped new or properly full-length sized cases will do.

It's my opinion that cases other than new or properly full-length sized ones touch the chamber at more places at the wrong time during firing. New or proper full-length sized ones present more consistant chamber contact during firing else they wouldn't produce best accuracy for so many folks. I've said this before: the smallest groups of 15 or more shots I know of at any range have all been made with new or properly full-length sized cases. I don't know all the techincal details of why nor does anybody else I know of; I let the test groups speak for themselves.

Most of you readers won't believe me; that's fine. Contact Sierra Bullets and the national champions and record setters of highpower competition who shoot 20-shot strings and ask them why they get best accuracy with new or full-length sized cases. They will not know all the technical details but instead let their scores and groups speak for themselves.

 

[goodgrouper]

Thanks for the enlightenment Bart although I was pretty well informed already about how bolt action rifles work.

Oh, and I did call Sierra about FL sizing vs neck and heard the same remark I made here several months ago: Do what shoots best in your particular rifle!! If it be neck sizing- then neck size! If it be FL sizing then FL size! Sierra's tech said they FL size to ease bullet testing in all available barrels during bullet production and avoid hanging up the process with a round that won't go back in the chamber. This would apply similairly to the highpower shooters you keep referring to. They need to shoot quick and have no hangups so they FL size. If it benefits their accuracy then that is a bonus!
The tech then pointed out another thing I said several months back: Both FL sizing and neck sizing can actually hurt accuracy if over or under done. The proper amount of sizing needs to be found and used on a consistent basis. If you FL size too much, run a concentricity gauge over the brass and see what happens! /ubbthreads/images/graemlins/wink.gif

Me thinks that the 6ppc rail gun I shot a few weeks back that put five shots into a nice .092" hole probably could not have shot a smaller group had I FL sized the brass!

Nor do I think that my 6br improved could have shot better than the 5.5" 5 shot group at 1k with FL sized brass last Saturday! Neck sizing these particular rifles seemed to work out well for me although I am not a member of your imaginary "top (bygone era) shooters" that you so famously cling and refer to. /ubbthreads/images/graemlins/frown.gif

Honestly, I would like to see some of the, ehhm, facts you preach be put into some personal evidence in your own shooting. THus far, you point to others for your testimony. If you want to lend more credibility to your POV, it would benefit you to include something other than armchair theory and third-person name dropping (although I admit there still have not been any real names used).