What went Wrong?
Small die setting mistakes can lead to problems that plague handloaders. Here are five common mistakes and how to fix them.
Dimples in Case Shoulders
Shoulder dimples in bottle neck cartridges are unsightly but relatively benign issues that can be easily remedied. The problem is cause by excess case lubrication during the resizing process which hydraulically forms dents.
Correcting the problem is simple. Clean out the die with a swab, reassemble and then use less lubrication during the sizing step. The dimples will blow out during firing, returning the case to its original configuration.
Use enough lube to ensure the case will easily enter the resizing die. If the case seems sticky going in, stop and re-lube. Dimples aren’t much of a problem, but removing a case stuck in a resizing die can be a real bearcat.
Crushed Cartridge Shoulder
Crushed or set-back shoulders are very common and caused by a couple of mistakes. They can cause problems with chambering as well as accuracy because the issue may affect headspace. Glancing at the problem, the resizing process would seem like a likely culprit, but it is usually associated with bullet seating.
The problem occurs when enough downward force is applied to the case neck during seating or crimping that it forces the shoulder to bulge within the seating die. There are two main causes for this problem. The first is neck tension.
As part of the sizing process, a button is passed through the case neck, leaving it several thousandths smaller than the bullet diameter. This neck tension is what holds a bullet in place. If the neck tension is too great (meaning the sizer button is too small) the force needed to insert a bullet can crush the cartridge shoulder. Replacing the sizing button may be necessary.
A much more common reason for shoulder set-back is excessive crimping. Seating dies are designed to crimp the case neck into the bullet to increase neck tension. The deeper a cartridge is pushed into the die, the more pronounced the crimp becomes. Setting a die to crimp heavily, or having cases with over-long necks, can crush the shoulder.
The best way to avoid crushed shoulders is to trim cartridges to the same length so they receive the same crimping force within the die. The other options are to reduce crimp pressure, or in the case of most bottleneck cartridges, forgo it completely and rely on neck tension to hold the bullet in place.
Over Crimping
Here is a simple rule: Crimping can be a good thing, especially in magnum pistol cartridges.
Here is another simple rule: Too much crimp is always a bad thing.
The line between a good, heavy crimp for a hard recoiling load and a bad crimp can be quickly crossed during the seating process. A good crimp locks the bullet into the cartridge, preventing it from “jumping” forward in the case under heavy recoil. Crimping a magnum is a good handloading practice. Crimping it too much makes trouble.
Over-crimping damages the bullet, even if it has a cannelure. This will affect accuracy. Extreme over-crimping will damage the case body, collapsing the case body (or shoulder if present) to the point that it will not chamber.
Correcting over-crimp requires a simple adjustment to the seater die. Back the die out and then re-set it on another charged case. Once the bullet is set to the correct depth, adjust the seater die body down until the proper crimp is set. Finally set the seater down onto the seated bullet and return to loading.
Another very good option is to crimp using another die after the bullet has been set to the correct depth. This adds another step, but it is the best method for producing high quality handloads.
Belling Issues
A lot of misery is caused because handloaders do not flair their straight-walled cases enough. Flaring (also called “Belling” by hip handloaders like us) opens the case mouth like a funnel, allowing the bullet to be seated slightly inside, rather than on the case mouth.
There are many cautionary tales told regarding case belling, owing to the fact that unnecessary working of brass reduces case life. The result is that handloaders under-bell their cases and end up damaging bullets, ruining cases, hurting accuracy and making a mess inside their dies. Don’t bell the cases too much, but bell them enough. Here are some simple guidelines regarding case mouth bell:
Lead bullets need more flare than jacketed bullets. 
Shaving of lead or jacket material is sign that more bell is needed.
If jacketed bullets damage the case wall, increasing the flare may help.
If the case drags in the seater die, it is over-belled.
If the bullets seems canted to one side in the loaded case, decrease the flare.
Sometimes going too fast will result in a bullet that is misaligned before the cartridge is run up into the seater die. They will produce results like the one shown on the left. Just be aware that an occasional damaged cartridge like this one may not be directly related to an under-belled case mouth. It may have been careless placement of the bullet instead.
Like most handloading skills, judging proper case bell is a skill that develops over time. For beginners, it is easier to simply bell the case large enough to easily accept a bullet and small enough that it will fit into the seater die without scraping. The increased case stress is worth the resulting well-seated bullet. Over time, setting the belling die will become more practiced and the amount of flare reduced to match the individual loading project.
Bullet Seated to Deeply
There is a difference here between rifles and pistols when it comes to the question of bullets that have been seated too deeply into the case. Rifles are more forgiving than small capacity, high pressure pistol cases, but neither case is good news for the handloader. The next rule applies to handloading across the board, but especially here: IF IT LOOKS FUNNY, DON’T SHOOT IT.
The 9mm Parabellum round shown has a 147 grain bullet seated too deeply into the case. It has distorted the case body above the web, producing a distinct bulge. The bullet bearing surface has been pushed below the case mouth, leaving a visible gap.
Internal changes within this case are significant. 9mm Parabellum cartridges operate at a SAAMI maximum of 35,000 psi, which is the same pressure threshold as a .357 Remington Magnum. What makes the 9mm Para especially nasty in this situation is that it uses faster powders in a smaller space than the .357 Magnum. It is very sensitive to changes in case volume. In this example, the bullet has taken up case volume that would have been available to allow gas expansion before the bullet began to move. The bullet is also compressing the powder charge, which can radically affect burn rates. The pictured cartridge will have more pressure than one using the correct Cartridge Over-all Length and the same powder charge. If you are confronted with this problem, salvage the components or safely dispose of the cartridge. Don’t shoot it and don’t keep it in a box of duds for your beneficiaries to find after you have passed on. This type of mistake is potentially dangerous.
Small mistakes in handloading are common and most are easily remedied. Some, like pressure dimples in rifle cartridges are unsightly but harmless. Others may damage cases and components beyond salvage, but that is part of challenge of learning a new hobby. Please, let caution rule your handloading choices. I you suspect something is wrong, safely dispose of it and move on. Some mistakes are trivial, but others ruin guns, hands and eyes. Always put safety first.