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Thread: Reloading Terminology
02-19-2011, 07:13 AM #1
This is a quick guide to reloading terminology and how it relates to the process of reloading.
Single-Stage Press - This is a press that performs a single stage of the reloading process at a time using a single die. For example, you'd install your sizing die and begin sizing all of the brass, and would have to switch to a powder die for the next stage in the loading sequence. An example of this is a RCBS Rockchucker press.
Turret Press - This is a press that uses a rotating tool head, but a fixed shell holder. All of the dies can generally be installed, and the operator rotates the tool head to move a single piece of brass through the various stages of loading. It's a bit of a hybrid between a single-stage and progressive. An example of this is a Lyman T-Mag II press.
Progressive Press - This is a press that has a rotating shell holder that "indexes" the brass through the various stages of reloading. The brass rotates into each station of the press which has it's own die / function. An example of this is the Dillon XL650 press.
Auto-Indexing - Referring to a progressive press; auto-indexing is when the shell plate is automatically rotated by pulling / releasing the lever.
Manual-Indexing - Referring to a progressive press; manual-indexing is when the shell plate is turned by hand.
Full Length Die / Sizing - A full length die will resize the entire case body, not just the neck portion. This is a necessity for loading for semi-automatic firearms of any caliber.
Small Base Die - This is a full length sizing die that forms the brass to even smaller dimensions than a standard full length die. This is a necessity for certain chambers found in semi-auto guns that have trouble cycling and/or feeding brass processed with a standard full length die.
Neck Sizing / Die - A neck sizing die will only resize the neck of the case, which is the narrow diameter portion at the top of a bottlenecked rifle case. This is a better method for loading precision bolt action rifle ammo, and prolongs the life of the brass case.
Bushing Neck Sizing Die - A customizable neck sizing die that uses a specified diameter bushing collet for greater precision when reloading match ammo. Proper sizing of the bushing is paramount for proper operation of this die, consult the manufacturer for methods on measuring the necks of your rifle brass and sizing the bushing accordingly.
Carbide Dies - Dies made of a carbide steel that reduce sizing effort and increase the longevity of the sizing die. In pistol calibers they also reduce / remove the need for case lubricant. They are generally found in most pistol calibers, and in very high volume rifle calibers like .223 Remington and .308 Winchester.
Micrometer Dies - These are dies that have adjustable micrometers installed to serve as a more precise methodology for setting seating depth (in most cases) and other stages of the the reloading process. RCBS and Redding both make micrometer seating dies.
COAL - "Case OverAll Length", meaning the measure of the spent brass case from end to end, lengthwise.
"Once-Fired" - This is brass that has been fired once in the gun.
"Fire Forming" - This is a process of firing the gun with either a loaded round, or a forming load with the intention of swelling the brass out to match the chamber. This is necessary on rifles with "Ackley Improved" shoulders unless proper "improved" brass is available, but is an integral part of getting the best accuracy possible in a bolt-action rifle. It is a moot procedure in a semi-automatic gun because you are going to full size the brass for feeding purposes.
Neck Turning - This is a process of milling down the thickness of the neck to improve the consistency of neck tension on the bullet and to improve uniformity.
Annealing - Using strong heat the shoulder and neck are heated and then quenched in cold water. This process will soften the shoulder portion of cases that have been work hardened due to repeated loading / firing cycles. This ultimately will improve case life, reduce sizing effort, and increase accuracy to some degree. It is recommended for Lapua and other investment quality brass. (This also is the source of discoloration on new brass cases)
Champfer / Deburr - You champfer the interior of the neck to facilitate the proper seating of a bullet, and following the champfer process you will need to flip the tool and deburr the edge.
Flash Hole Deburring - The small hole between the primer and powder charge is important to maintaining burn rate consistency. You can use a tool to deburr the flash hole to ensure case to case consistency.
Ackley Improved / "Improved" - This is a case that has had it's shoulder reprofiled to a 40 deg. shoulder angle as a means of increasing brass life and, more importantly, increasing the powder volume of the case and it's resulting velocity performance.
Ogive (Pronounced: "O-jive") - The measure of the bullet's taper from the shank to the tip. A shallow ogive is generally found on match and VLD bullets for increased aerodynamics, whereas low grain weight bullets of a particular caliber generally feature sharper ogives.
Meplat - On a hollowpoint rifle bullet the meplat is the folded hollow tip.
Meplat Trimming - The meplats can be trimmed to achieve greater uniformity at the cost of a small loss in ballistic coefficient.
FMJ - Full Metal Jacket; a copper jacket covers the lead core.
TMJ - Total Metal Jacket; the jacket encases the normally exposed bottom which reduces lead fouling and lead particulates in the air. (Pistol Bullet Designation)
JHP - Jacketed Hollow Point; an exposed hollow-point profile that facilitates large amounts of expansion in pistol bullets, and generally controlled expansion in rifle bullets.
BTSP - Boat Tail Soft Point, an exposed lead tip which facilitates bullet expansion upon impact. Popular and cheap for hunting usage.
BTHP - Boat Tail Hollow Point (Match Bullet or Varmint Bullet)
AMax - Hornady's Match Bullet
SMK - Sierra's MatchKing Bullet
# gr. - Refers to the grain weight of the bullet. One grain is equal to 1/7000th of a pound. (Example: 175 gr. SMK = 175 grain weight Sierra Match King)
Shank - The cylinderical bearing surface of the bullet that is seated into the case.
VLD - "Very Low Drag" bullet design, commonly made by Berger for optimal ballistic coefficient and long range shooting.
Bullet Diameter - The measure in caliber of the bullet itself. Not to be mistaken for it's loaded caliber, examples being ... .355" is used by 9mm Luger, .380 ACP, .38 Super, and .357 Sig, 9x21, 9x23, and 9x25 Dillon as a common bullet diameter.
Burn Rate - The burn rate of powders is EXTREMELY important to all aspects of reloading, it simply dictates how fast the powder burns and it's resulting pressure curve.
Spherical / Stick / Flake / Etc. - Are all powder granule geometries. Powder burn rates and metering precision are two factors that change in regards to the specific geometry of the powder.
SC or SSC - In reference to a powder name this is a "short-cut" or "super short-cut" version of the powder. An example is 4831SC, which has similar ballistic performance, but meters better in the powder thrower.
Jammed - Bullet is loaded at a sufficient length that it is engaging the rifling when chambered. Some guns like this, other don't. Use caution as this seating length will generally show pressure signs when approaching max figures faster than the "jump" depths.
Jump - Bullet is loaded at a length that is not engaging the rifling when chambered. The bullet will generally be measured in thousandths of an inch off the rifling. For example, "175 gr. SMK loaded 2 thou off the lands", meaning the bullet is .002" away from engaging the rifling.
OAL - "OverAll Length", meaning the measure of the loaded ammunition from end to end, lengthwise.
Seating Depth - The variation in how far the bullet is seated into the case; thus affecting the OAL and the amount of jump / jam. It also has implications on how fast and how much case pressure is built up.
"Over Book" - Rounds that are loaded up to max or beyond the max suggested charge weight / pressures by SAAMI. Not recommended unless you know what you are doing.
"Pressure Signs" - Certain aspects of the case, firing event, or (more likely) primer that indicate significant amounts of high pressure build up. Generally an indication that you are approaching or have found the max loading for this caliber.