Need help with bump sizing.

[Stumpkiller]

Just measure a few fired cases with the Hornady cartridges case headspace gauge and then set the die to bump the shoulder back .001 to .002.

After firing the case springs back from the chamber walls and is smaller than chamber dimensions. This is good because the case can be extracted without binding and easy bolt movement.


^^^That.

You want the case close to the size of a fired case. BUT not so close that "in the field" in hunting/dirty/different temperatures it doesn't close in the action. Measure the shoulder on a fired case and measure the shoulder on a resized case. Use the case holder that is just below that difference.

(I thought I did answer that question up above(?))

[Deadshot2]

With the competition shell holder it allows the die to make hard contact with the shell holder with press cam over. This takes all the slop out of the press and thus more uniform shoulder location.

You can also pause at the top of the ram stroke for 4 or 5 seconds and this will greatly reduce brass spring back. The more the case neck and shoulder are work hardened the more spring back you will have that effects bullet grip and shoulder location.

The best part about the Redding competition shell holders is you never have to touch the die to adjust the amount of shoulder bump.

The Redding Competition shell holders should also be used in conjunction with the rifle you are loading the ammo for. Following Redding's instructions one starts with the largest number shell holder and after sizing checks for fit in the rifle chamber. (Ideally with a stripped bolt the first time) If the case doesn't fit well, and bolt closure is hard, use the next lowest number (.002" more "bump") and repeat until the case fits and the bolt closes "just right". Once this is done then that number shell holder can be used for all cases being sized for that rifle. When using a press that has a decent amount of "cam over" makes for exceptionally uniform case dimensions.

Remember that when sizing a case with any taper in it, different shoulder set backs also means different case dimensions all along the case wall, from shoulder to head.

[88Magnum]

I did measure with the hornady gauge and my measurements were 1.538 to 1.539 so a .002 bump would give me around 1.536 and some were 1.535 to 1.536.5 unless my calipers are not that good (I'm getting a Mitutoyo set) and this gave me a good bolt close and bolt open so I think I finally got it. The competition shell holder set made it much easier, I think I was screwing things up by over and under adjusting the die.

Thanks all for the time and all the help. :rockon:

[yobuck]

Whats so awfully wrong with just following the simple instructions that come with the dies?
I always have full length resized because I'm primarily a hunter, that's what i was recommended to do.
Ive never in over 60 years had any problem by adjusting the die down till i get the bump the directions recommend.
As Salazar said, primer pockets always go first anyway, especially with the large capacity magnums.

[bigedp51]

Whats so awfully wrong with just following the simple instructions that come with the dies?
I always have full length resized because I'm primarily a hunter, that's what i was recommended to do.
Ive never in over 60 years had any problem by adjusting the die down till i get the bump the directions recommend.
As Salazar said, primer pockets always go first anyway, especially with the large capacity magnums.

Chambers and dies vary in size meaning in diameter and headspace length. Example I have a Lee .223 full length die that will push the shoulder back .009 shorter than a GO gauge if setup per the directions. On top of this the same lee die will reduce the case diameter more than my RCBS small base die.

The reason they tell you to use .001 to .002 shoulder bump is this is well within the elastic limits of the brass when the rear of the case stretches to meet the bolt face.

This doesn't mean every die will push the case shoulder back too far. But what it does mean is you can adjust the die for minimum head clearance which is the same as shoulder bump on a chamber cartridge.

https://i.imgur.com/HK76WCp.jpg

Below there is a big difference between .001 to .002 below the red dotted line and .009 shorter than a GO gauge close to the green dotted line.

https://i.imgur.com/wm05ArY.gif

Bottom line there is a reason why Redding makes their competition shell holder that let you push the case from .002 to .010 "LESS" into the die.

Another example, if I use my RCBS .223 die and shell holder with the die adjusted per the instructions the shoulder will be pushed back .007. But by using the Redding +.004 competition shell holder I will have .003 shoulder bump for my AR15.

In the past reloaders would use feeler gauges to adjust the die and the amount of shoulder bump as pictured below.

https://i.imgur.com/7FfXhJ7.jpg

Bottom line, if your cases fail of cracked necks before you have a case head separation your die is a good match for your chamber. "BUT" if you have a case head separation after just a few reloads you are bumping the case shoulder back too far.

Below a example of firing a military .303 British Enfield rifle at max military headspace of .074 and a rim thickness of .058 with .016 head clearance. Meaning it is the excessive head clearance that causes case head separations. And again your shoulder bump is equal to the head clearance when the cartridge is chambered.

https://i.imgur.com/sHgqVJR.gif

[OLEJOE]

I full length size my cases and bump my shoulders back.0015. When adjusting the die, the shoulder will actually move forward until you start getting the die adjusted properly. When the die squeezes the case sides in, it displaces the brass forward and increases the length. Keep adjusting the die downward in very small increments until you get the measurements you need. Once adjusted, tighten the lock ring and you are good to go.

[88Magnum]

I full length size my cases and bump my shoulders back.0015. When adjusting the die, the shoulder will actually move forward until you start getting the die adjusted properly. When the die squeezes the case sides in, it displaces the brass forward and increases the length. Keep adjusting the die downward in very small increments until you get the measurements you need. Once adjusted, tighten the lock ring and you are good to go.

Try this..go into powerlifting most of your life, set deadlift records and squat records at the 222 lb weight class as a teen, go up to 275lbs and push thousandths of lbs every week for over 20 yrs. Now, grab a sensitive piece of machine like die set with very fine adjustments and start adjusting. Just make sure you don't break many things after the first 2 hrs you keep over adjusting and under adjusting because you just can't get it to a fine enough adjustment. Remove the die with gorilla hands and mess the whole thing up and have to start over again losing your place, try this a few hrs and then see how easy it is. Some of us break things just by looking at them, I already came close to snapping the arm on the rock chucker and screwed up the threading on it. My work has banned me from working with canvas because I rip $5000-$7000 graphics by pulling on them. Others tug away with two people with no issues, I tug on it and I rip it 4 yds. Some of us are a little different my man.

[OLEJOE]

Well “My Man” get your wife or girlfriend to do it for you. Maybe a kid from the neighborhood.

[88Magnum]

Well “My Man” get your wife or girlfriend to do it for you. Maybe a kid from the neighborhood.

I already explained that I got it down with the competition shell holders. Everyone else was very helpful or at least tried to help, why did you bother to comment? Following the instructions won't work with every rifle, I tried that with my first set of dies, Lee, and I had to back it off by more than what it says.