So, I'm loading up all my brass that I have for my 7mm Weatherby magnum. A few fresh cartridges fall over and roll across my bench. wooba wooba. Some of the projectiles are WAY crooked in the cases. I use a Hornady neck size die to do about 3/4 of the neck, and seat with a Lee collet bullet seater. die. What gives?
controlling runout
- Thread starter ffwd
- Start date
PerversPépère
CGN Ultra frequent flyer
- Location
- Shawinigan (Quebec)
Hornady has just the right thing for you: it's a bullet runout checker with dial and a means of straightening your rounds.
PP.
PP.
Mystic Precision
CGN Ultra frequent flyer
- Location
- Summerland, BC
You should get a runout guage to determine where the runout is being created.
- from a wonky chamber? measure case as it comes out of the chamber. Should have ZERO runout.
- from your sizing die? Dies with expander ball and rods may be bent bending your necks as the expander ball is extracted.
- from your seater? Standard dies can be too big and not support the cartridge at all during seating. Also, the seating stem may not be the correct shape for the bullet.
If these three areas check out, you will have straight ammo. Otherwise, you can get better dies or rechamber the rifle.
Jerry
- from a wonky chamber? measure case as it comes out of the chamber. Should have ZERO runout.
- from your sizing die? Dies with expander ball and rods may be bent bending your necks as the expander ball is extracted.
- from your seater? Standard dies can be too big and not support the cartridge at all during seating. Also, the seating stem may not be the correct shape for the bullet.
If these three areas check out, you will have straight ammo. Otherwise, you can get better dies or rechamber the rifle.
Jerry
Me too, although there were a few pieces of brass that just always developed runout. They came fired out of the chamber straight, straight after sizing with the Collet Die but seat a bullet and suddenly runout. Same pieces of brass each time.
Those pieces have been seperated from the good stuff.
The most likely culprit IMO is that your expander ball is pulling the case neck out of alignment.
- Location
- Somewhere on the Hudson Bay Coast
Jerry has the correct answer of course. You should check the run-out of your neck at each stage of your handloading process. Start with the fired brass right from the rifle, the run-out should be very close to zero. If you have run-out after resizing, you may have to recenter the expander ball in the die, or perhaps your shell holder is not true. You may find that rotating the case on the shell holder and resizing in small steps might fix it. If the run-out occurs when seating the bullet, make sure the seater stem is straight and tight, and again seat the bullet in a couple of steps and turn the case on the shell holder. Sometimes the retaining spring on the ram will hold the shell holder askew, so you might benefit by exchanging the retaining spring for a rubber "O" ring and allow the shell holder to float back and forth on the ram to find its own center. "O" rings can also be used under the lock nuts of the die, the decapping rod lock nut, and the bullet seater lock nut so that they too can find their own center.
And when your done your checklist (all good info) buy a Forester Co-ax press.
Used a good quality lube on your brass and clean your dies every dozen or so cases. Make sure the die vent port isn't plugged up which will create excessive hydraulic pressure (dents) inside the die right at the case bottle neck. If you’re using a collets neck sizing dies or regular full length dies with close and interference fits, you can expect a few distortions, which will also depend on the brass thickness and camber dimensions it was last fired in.
Feel free to split hairs if that's what you’re into with go and no go gauges. Keep in mind case expansion and elongation with trimming requirements, reaming burs to even what type of bullet your trying to seat all has it’s effect on the final product.
Hope that helps a bit.
Driller
Feel free to split hairs if that's what you’re into with go and no go gauges. Keep in mind case expansion and elongation with trimming requirements, reaming burs to even what type of bullet your trying to seat all has it’s effect on the final product.
Hope that helps a bit.
Driller
- Location
- Somewhere on the Hudson Bay Coast
I like the Forster Co-ax, but it is intersting that they have not modified their yoke to accomodate the long dies that come with competition sets. The longest die I have is a Forster seating die for my .375 Ultra, and there is no way it wold work on their own very good press.
I beleve there is a retrofit hande that fixes this, I run lots of comp dies.
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Redding Competition Seating Die will probably help alot.
C/P from Redding site.
The concentricity, or neck runout, of loaded cartridges is an important consideration for reloaders and especially the varmint or target shooter.
There are many factors that can cause or contribute to neck runout during the reloading process and many reloaders who have not dealt with the problem before quickly blame the sizing or seating die.
While the dies may be at fault or have a contributing defect, modern CNC machinery and reamers that cut the body, shoulder, and neck simultaneously make such occurrences rare. Most problems are related to the brass itself and its uniformity both in terms of hardness and thickness and how much it is being stressed in the reloading process.
An entire book can be devoted to this subject, but the amount of stress the brass is subjected to can be your key to finding a problem. If you "feel" any difficulty and /or heavy resistance when resizing your cases this can be a telltale clue.
Excessive difficulty while resizing can indicate any of the following: Poor choice of case lube, failing to clean the die and/or brass, faulty polish inside die, chamber large or at maximum S.A.A.M.I. spec resulting in excessive brass resizing. A large neck diameter in the chamber combined with brass that is thin or excessively turned can cause crooked necks in a hurry. The more brass has to be moved the more its residual memory takes over.
Resistance to pulling your cases over the size button can indicate problems. A "squawk" says "shame on you", you forgot to brush the residue out of the necks. A hard drag can indicate that the top of the size button is not smooth. Don't be afraid to polish the top radius with #600 wet paper, but don't reduce the outside diameter or you can create an excessive bullet fit. Carbide size buttons are now an option also; they have a lower coeffecient of friction.
We have conducted many tests over the years on the various factors contributing to concentricity problems with bottleneck cases. We have repeatedly found a definite correlation between the uniformity of the brass (or lack of it) and the resulting concentricity of the neck to the body of the case.
An interesting experiment also revealed that neck turning of brass that was intentionally sorted as non-uniform, showed little or no concentricity improvement when used in standard S.A.A.M.I. spec chambers. Conversely brass that was sorted and selected for uniformity remained uniform and concentric with or without a neck turning operation.
Another interesting observation can be found in the examination of fired cases that have crooked necks "as fired" right out of the chamber. Usually the chamber is being blamed for the problem.
Looking at the primers under magnification you can usually find a telltale machining mark or other blemish that was imprinted from the bolt face. This will give you an index mark with reference to the chamber. Mark this index mark on the cases with a felt tip marker and go about checking the concentricity. If the runout is random to your index marks the problem is not the chamber. Further examination will show the same correlation with the good and bad brass.
Note that to this point we have not talked about seating dies. That is because 98% of all concentricity problems exist in the brass prior to bullet seating.
Keep in mind that no seating die ever made will correct problems. The best you can do is to obtain a quality seating die that does not add any.
UPDATE: Feb. '96
Redding has now introduced neck sizing dies that use interchangeable sizing bushings in .001" increments. These dies can help reduce overworking of the brass and the resulting loss of concentricity.
http://www.redding-reloading.com/techlinepages/concentricity.htm
C/P from Redding site.
The concentricity, or neck runout, of loaded cartridges is an important consideration for reloaders and especially the varmint or target shooter.
There are many factors that can cause or contribute to neck runout during the reloading process and many reloaders who have not dealt with the problem before quickly blame the sizing or seating die.
While the dies may be at fault or have a contributing defect, modern CNC machinery and reamers that cut the body, shoulder, and neck simultaneously make such occurrences rare. Most problems are related to the brass itself and its uniformity both in terms of hardness and thickness and how much it is being stressed in the reloading process.
An entire book can be devoted to this subject, but the amount of stress the brass is subjected to can be your key to finding a problem. If you "feel" any difficulty and /or heavy resistance when resizing your cases this can be a telltale clue.
Excessive difficulty while resizing can indicate any of the following: Poor choice of case lube, failing to clean the die and/or brass, faulty polish inside die, chamber large or at maximum S.A.A.M.I. spec resulting in excessive brass resizing. A large neck diameter in the chamber combined with brass that is thin or excessively turned can cause crooked necks in a hurry. The more brass has to be moved the more its residual memory takes over.
Resistance to pulling your cases over the size button can indicate problems. A "squawk" says "shame on you", you forgot to brush the residue out of the necks. A hard drag can indicate that the top of the size button is not smooth. Don't be afraid to polish the top radius with #600 wet paper, but don't reduce the outside diameter or you can create an excessive bullet fit. Carbide size buttons are now an option also; they have a lower coeffecient of friction.
We have conducted many tests over the years on the various factors contributing to concentricity problems with bottleneck cases. We have repeatedly found a definite correlation between the uniformity of the brass (or lack of it) and the resulting concentricity of the neck to the body of the case.
An interesting experiment also revealed that neck turning of brass that was intentionally sorted as non-uniform, showed little or no concentricity improvement when used in standard S.A.A.M.I. spec chambers. Conversely brass that was sorted and selected for uniformity remained uniform and concentric with or without a neck turning operation.
Another interesting observation can be found in the examination of fired cases that have crooked necks "as fired" right out of the chamber. Usually the chamber is being blamed for the problem.
Looking at the primers under magnification you can usually find a telltale machining mark or other blemish that was imprinted from the bolt face. This will give you an index mark with reference to the chamber. Mark this index mark on the cases with a felt tip marker and go about checking the concentricity. If the runout is random to your index marks the problem is not the chamber. Further examination will show the same correlation with the good and bad brass.
Note that to this point we have not talked about seating dies. That is because 98% of all concentricity problems exist in the brass prior to bullet seating.
Keep in mind that no seating die ever made will correct problems. The best you can do is to obtain a quality seating die that does not add any.
UPDATE: Feb. '96
Redding has now introduced neck sizing dies that use interchangeable sizing bushings in .001" increments. These dies can help reduce overworking of the brass and the resulting loss of concentricity.
http://www.redding-reloading.com/techlinepages/concentricity.htm
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