This die is designed to improve accuracy by overcoming some of the flaws of the typical crimping dies now on the market. As you probably know, a crimp is applied to ammunition so it can withstand rough handling such as when it is being fed through the action of a firearm. A crimp also serves the purpose of preventing bullets from working their way out of the case when they are in the cylinder or magazine of a heavy recoiling firearm. That is due to the inertia of the bullet during recoil. A crimping die is also used to remove the belling of the case mouth that many powder charging dies make. The belling is used so that soft lead bullets won't be shaved by the case mouth as they are seated to depth. A crimp also will change the pressure curve because it allows the pressure to build up to a higher level before the bullet will release from the casing.
Some flaws of typical crimping dies are:
1. The "one size fits all" internal dimensions of typical crimping dies do not compensate for brass that varies in length, thickness, and hardness. They also do not compensate for variations in bullet diameter and hardness. If you measure any two bullets or any two cases close enough you will detect some difference. When they are loaded and crimped the two rounds will have a somewhat different bullet pull(amount of force needed to pull or push the bullet from the case). This affects the pressure curve and the timing of the internal vibrations of the various parts of the firearm. These different vibrations of the muzzle occur well before the bullet ever leaves the barrel and that expands the group size. That's also why most rifle shooters avoid crimping their ammunition if it's at all practical. Pistol shooters accept it as a necessary evil. It is truly mid 19th century technology and hasn't substantially changed since the invention of one piece metallic cartridges in the early 1800's. Actually you are using the exact same technology as general Custer used. Hopefully your targets are friendlier than his.
2. There is no way to quantitatively describe the amount of crimp being used on a batch of ammunition. At best we can use the words "none", "light", "medium", "heavy", or "military" and then leave it up to everyone's interpretation. In a field where chambers, barrels, dies, and bullets are manufactured to ten-thousandths of an inch and powder is measured to tenths of a grain(1/70000 of a pound) such words are strangely out of place and point to an area that cries for some refinement. Once a die is removed from a press and then replaced it is nearly impossible to return to the previous setting unless index marks were put on both the die body and the top of the press.
3. Many crimp dies have no facility for cleaning without removing them from the press. Once cleaned they have to be adjusted all over again so the crimp "looks" about right. The Dillon crimp die avoids the cleaning problem with a removable insert.
4. A separate die is usually needed for each caliber. A 40 S&W crimp die will work for a 10mm but not visa versa. The same goes for 38/357, 44/44mag, and a few others. This all requires some trial and error to produce adequate crimps when changing from one caliber to another compatible one. A hint - if you ever get it just right, use a magic marker to index the die with the press so you can reset it. At most you will be a full revolution off which is easy to detect and correct.
5. Current crimp dies give very little "feedback" as to how much pressure they are applying to crimp each round. At best one can feel the difference in the force needed to work the press handle. With progressive presses where more than one operation is done with one stroke of the handle it is hard to tell if the crimp is somewhat unusual or if one of the other operations such as the case sizing, powder charging, or bullet seating is causing the different feel. That makes "odd" rounds harder to detect.
There is a completely new type of crimping die entering the market that avoids all of the above flaws. This die has a "floating" crimp ring that is held down by a leveraged weight. When the upward pressure of the ram exceeds that weight, the die ring, round, lever, and weight slide up and cease crimping the round. Because the die ring "floats" vertically, it can actually compensate for minor variations of casing length, thickness, and hardness as well as bullet variations in diameter and hardness. The result is that the exact same force is employed to crimp the brass onto the bullet, regardless of minor variations. This in turn gives a much more uniform bullet pull and as a result a more uniform pressure curve and set of internal vibrations. That translates into greater accuracy. Hundreds of 10 round groups fired through several accurized M1911 type 45 ACP pistols using a Ransom rest have shown reductions in group size of 5% to 25% and sometimes more depending on the uniformity of the brass and the amount of force used. In a field infested with machinists, the standard approach to get uniform bullet pull is to make as many of the components as possible to the closest functional tolerances. This new die approaches the problem of uniform ignition and bullet pull by using the very constant force of gravity while at the same time utilizing all the benefits of the older approach. With this die the minor variations in case and bullet show up as slight variations in external dimensions of the loaded rounds, and do not affect the amount of crimp. A major asteroid hit on earth would probably make less of a change in the earth's gravity field than a 10 or 20 degree temperature change would make in the dimensions of a die because of metal expansion. We'll leave that to the physicists. Your 45 auto will never shoot like a bench rest rifle but more uniform ammunition should make it shoot better.
With the leveraged weight we can now tie a precise number to the amount of crimp used on a batch of ammunition. Preliminary results show that 125 pounds of force will taper crimp all brands of 45 ACP brass enough so they will enter a rather tight Gil Hebbard match grade loaded round gage. 85 pounds of force seems to give the best accuracy with a uniform batch of PMC brass and the 200 grain type 68 lswc's from Oregon Trail. Thinner brass such as RP require less force, and thicker brass such as Federal require a little more. Recent data for the smaller calibers show the following amounts of force will crimp mixed head stamped brass with lead bullets enough so they will fit Midway loaded round gages: 9mm Luger-88 lbs., 380 ACP-104 lbs., 40 S&W-120 lbs., 38 Special-100 lbs. Now when we discover a hot shooting load we can precisely specify the amount of crimp used and then repeat it months or years later. To use the die, the reloader must first add 6 to 10 pounds of lead shot, bullets, etc to the weight container which is then suspended from the lever at one of the grooves. A postal package scale or accurate bathroom scale is handy to measure the amount of weight used. Then a simple calculation will yield the amount of force being put into the crimp. Hint, 35-200 grain bullets equal 7000 grains which also equals one pound. The amount of weight used times the leverage ratio at the attachment groove plus 8 lbs for the lever itself is the amount of force atop the die ring(F=8+W*R). It has been noticed that continual firing of a particular batch of brass will slowly work harden the brass so that the amount of crimping force has to be slowly increased to compensate and assure proper outside diameter and functioning. 45 ACP caliber brass, unlike rifle brass, also tends to shrink in length as it is continually reloaded and fired. Its sort of like the old carpenter's lament "I trimmed it twice and its still too short". For these reasons it is recommended that each batch of ammo reloaded be checked with a loaded round gauge or maybe even better, the chamber of the gun in which it will be fired. This is where the compensating feature of this die promotes uniformity and better groups. See the "other data" page for shrinkage test data in typical brass and loads.
This die is also very easy to clean without changing its adjustment, merely remove the weight and lever and push the guts of the die out the top using a 3.75" pencil, dowel, or the base of a round such as a 300 H&H Mag from below. Clean the die ring and reassemble in reverse order. The body of the die and the lever housing have not moved so no readjustment is needed. There is a lot of room in this die so frequent cleaning shouldn't be necesssary. A drop of oil on the sliding parts is reasonable as is a drop or two on the ball bearing and pivot pin. Don't use moly type lubes on the ball bearing as it is harder than the ball and may ruin it. Moly is great for sliding parts but not for rolling ones. Lubrication minimizes friction and optimizes consistency to say nothing about preventing rust. Hey, its machinery, its perfectly legal to oil it!
A happy feature of the constant force design is that by watching the movement of the lever it is possible to spot rounds that move the lever differently than the rest of the batch. If the user were to attach a stylus to the end of the lever and place a piece of graph paper adjacent to the stylus it would be possible to sort ammunition into groups with similar characteristics. This further improves the chances of getting smaller groups by eliminating the occasional odd round that could cause a flyer or even worse, a malfunction. It might even be possible for some enterprising engineer to add limit switches and contacts to "flag" abnormal rounds much like Walt Berger does with his computer controlled bullet swaging setup.
Because of the sliding crimp ring and general design of the lever portion of the die it is quite easy to adjust. Just put a properly crimped round in the press and raise it up into the die. Screw the die down until the lever with no weights on it swings up to 10 or 20 degrees above the horizontal. Lower the ram and then add the weight container. Try crimping a round and adjust if necessary by screwing the die in or out of the press using an unweighted lever. With the ram down the lever will naturally hang down. As the ram is raised near the top of its stroke, the round contacts the crimp ring which starts crimping the round until the ram force exceeds the weight sitting on top of the crimp ring. Then the lever will lift up above horizontal and the crimping process will stop. Once a properly crimped round is produced, lock the die onto the press. Next swing the lever around to position it and the weight bottle out of the way to avoid any structures such as a powder measure or case feeder. Then gently snug up the lock screw on the lever housing. Because of its design a 380 ACP crimp die can be used with 9mm Luger, 9x21, 9x23, 9x25, 38 Super, etc just by screwing it out of the press as appropriate. It could also be used for 38 Special and 357 Magnum ammo if a taper crimp is desired instead of a roll crimp as is typical. The 380 ACP die would have to be screwed out .61 or about 8.5 revolutions to allow it to work with 357 Magnums and .48 or 6 and 3/4 revolutions to work with 38 Specials. This use of a short case caliber crimp die with a longer case caliber may not be feasible depending on the make of press and number of threads available. It would actually be easier to just change the internal spacer tube which takes just a few seconds. The constant force crimp die is designed so that the "guts" of the die can be changed for use with various calibers and require little if any readjustment.
Your old style crimp dies are just as usable as ever but they are probably not giving you the best possible results. Put them aside and get a twentieth century crimp die before the millennium ends. Your firearms may be more accurate than you ever thought they were.
If your accuracy problems are due to variations in powder charge, poor primers, low grade bullets, over all length of the round, bad headspace, bullet diameter to bore mismatch, leading, wrong powder type, firearm problems, or human error, the constant force crimping die will not be able to improve your groups very much. The constant force crimp die only helps remove that portion of the inaccuracy that is contributed by non-uniform crimps. If your firearm is really a collection of loose parts flying in formation you should first make a trip to a good gunsmith, then start using a constant force crimping die with some good quality components.