1. Why must I begin loading at the recommended “START” load?

The GOLDEN RULE of reloading is to always to begin at the recommended START load, which is between -10% below the MAXIMUM load for most Rifle calibers and up to 15% below for certain handgun calibers.

The 1st and foremost reason is SAFETY:

Due to a myriad of variables that can exist and which is totally outside the control of the institution which generates the reloading data, it is imperative to consider the safety aspect and begin at a properly reduced low energy level.

The 2nd Important reason is OPTIMIZING for ACCURACY:

The ability to induce a wide range of energy levels, will improve the ability to “find” the optimal “sweet spot” and the smallest possible group for a particular weapon system/platform, and component combination, i.e. primer, case, powder and bullet.

2. How is the data in your load guides acquired?

All the testing is done in test barrels according to primarily to SAAMI and in some cases the CIP specifications (International protocol).

  • The pressure is measured with a piezo electric transducer which measures the real true pressure in psi.
  • Velocity is measured 15 feet from the muzzle of the barrel.

3. What are the signs of “unstable” powder or powders that are decomposing?

  1. Yellow-/brown-/orange-ish fumes and/or powdery deposits, on the powder or on the inside of the container/s.
  2. A Strong Acidic smell that takes breath away (not to be confused with the normal solvent smell.)
  3. Any rusting of metal objects, in contact or close to the powder.

4. What advantage do I have measuring the velocity?

Whenever, it is possible to measure a parameter accurately, it is a huge advantage to know/conclude what is happening. It will immediately tell you whether the combination is in-line with the published reloading data or not. The availability of affordable and accurate chronometers has put this measuring ability within reach of most reloaders today.

5. What is the real story behind temperature stability?

Most of our powders are not insensitive, and will show some effect at hot and cold temperatures.

However, we test at -40F and +125F and the deviation in most cases are ca 3% to 5% at these extreme levels. Therefore most shooters do not notice much difference under normal practical hunting conditions.

 More elaboration on the subject:

Complete temperature stability can only be achieved with tubular extruded powders designs, either with double base (NG) and/or with other coating technologies.

Because the ballistic performance at extreme temperature is completely dependant on the specific combination, it is very difficult to quantify and qualify.

Our standard powders perform very well at extreme temperatures, and usually pass the strict military requirements by a large margin.

This is a subject that often fraught with misconceptions and inaccuracies.

The term is used loosely by manufacturers without qualifying the subject, and is obviously exploited for marketing purposes and perceptions.

The facts are:

  • Although powders can be improved, it’s really only possible with advanced coating procedures and additives which increase the cost.
  • A particular powder can be improved re temperature stability for certain combinations, within a certain envelope which is specific to the following three main parameters/aspects
    • The caliber.
    • The weight of the projectile/bullet.
    • The performance level.

If any of these parameters/aspects go beyond or outside the intended ratio/s, the results will change and the performance will sometimes be different.

It is also very important that when a comparison is made, that all conditions re weapon i.e. components primer, case, bullet and the velocity are equal, and preferably done at the same time on the same day.

6. How can I achieve or determine an accurate load for my rifle?

Accuracy is totally dependant on the specific combination, and is therefore impossible to predict.

The dispersion of the bullet is largely determined by the stability of A) the launch platform/system, which off course includes the shooter, as well as B) The external ballistics of the bullet in flight. The launch platform stability is controlled, and determined, by a complex interaction of the different components primer case bullet and gun (as well as shooter) none of which can be considered “accurate” as a separate entity.

It’s is not correct, and a common misconception, to assume that there are so called “accurate- powders, primers, cases, projectiles etc. Any one of these claims can be easily disproved with a different combination. It is true that some weapons are inherently unstable and no matter of combination will reliably deliver acceptable accuracy.

These components aspects/parameters all contribute to the “launch-impulse”, and performance level (velocity and pressure). The dynamic characteristics of this impulse are therefore very specific for each combination. How the launch platform/Rifle reacts to this impulse, determines the launch stability, and as a result the accuracy/dispersion. This specific reaction of the launch platform can be described the “dynamic character or -finger print” of the weapon/ammunition system. That’s why an “accurate load/combination” can only be achieved through incremental adjustments, and/or variations of these different components, and parameters.

The only way to properly do this is, to always start at the minimum or start load, and work up towards the maximum suggested load, with the components at one’s disposal. If the desired accuracy is not achieved, the second phase will be to adjust or change the components, i.e. primer, case, case condition, projectile/bullet or the type of powder altogether. The important thing to remember is to change/vary only one parameter/component at a time.

We refrain from predicting accuracy. Although some people, and institutions, recommend so-called “accurate loads” and combinations it’s not very well founded or scientific because, the assumption is made that all systems and conditions are equal, which is not true.

7. Why does excessive leading occur in the so called “smooth” internal rifling profiles such as polygon of hexagon barrels.

Because some internal barrel profiles (Mostly for handgun calibers), such as the polygon® and hexagonal® have unconventional “smooth” internal dimensions, its inevitable that the diameters of these barrels be extremely tight, to engage the bullet in order to impart the rotational forces for stability. When cast bullets are used in conjunction with these barrels, it imperative that the dimensions should be sized correctly, and that the hardness be such as not to cause any lead fouling. Any build-up or deposit of bullet material in the forcing cone freebore/lead area might result in a high pressure and the resultant damage to the weapon and/or injury to the shooter.

8. Are powders hygroscopic? (Also see question 9 below regarding static electricity)

It depends on the specific composition of the powder itself, and also the geometry. Modern smokeless powders can be divided into two main groups.

Single base:

Geometry: Extruded Flake/Disc or tubular.

Double base:

Geometry: Ball/spherical or extruded flake/disc or tubular.

Single base powders:

Single base powders are more hygroscopic than double base.

Since the vast majority of this powder consists of just NC Nitro Cellulose, and does not contain other ingredients which will seal the powder composition, it will be more porous, especially some of the extruded flake/disc powders aimed at shotgun or handgun applications.

Double base Powders:

When Nitroglycerin is added, the product is gelatinized or plasticized which will result in the grains being less porous and “sealed” against external atmospheric conditions.


If the individual granules are extremely small the chances of it sticking/clinging to synthetic materials are more possible.

Even double base ballpowders, such as in the case of extremely fast burning ballpowders for Shotgun/handgun applications, which can also be sometimes rolled/flattened, will also tend to cling to the sides of synthetic (static) containers/hoppers.(see question below re static elecricity)

Flash suppressant;

Another component that will casue powders to be more hygroscopic is when flash suppressants, which is basically salts, are part of the composition.

It will also therefore depends on if, and what percentage of flash suppressant is present in specific powder.

In general we can state that:

  1. That Extruded Singe base powders will tend to be more Hygroscopic and because of the lower density of such powders it will also show a greater tendency to stick to the sides of hoppers etc.
  2.  If you are loading in extremely dry or wet conditions, it will allways be good to keep the containers hoppers etc closed and well sealed.
  3. Double base powders, such as the typical spherical/ball types as well as the modern double base temperature stable extruded tubular powders, are extremely robust when it comes to envirionmental issues. That’s why these are now the standard used by the military.

9. What can I do to eliminate static electricity in powders, hoppers and filling equipment?

There are a few things one can do to alleviate or eliminate static electricity.

A) Add a very fine grained “lab grade” graphite powder to the powder, at about 1 teaspoon per lb and shake very well.

This is usually available at hardware stores in the lock/key departments or from laboratory equipment/material suppliers.

This graphite can also be rubbed into/onto surfaces in contact with the powder.

Caution: This powder is extremely fine and will be difficult to get of skin so we strongly suggest using surgical gloves when handling the graphite. Also take care not to spill it on clothes because will be hard to clean. Hard to reach places can be treated with cotton swabs dipped in the graphite powder.

Another option is to rub the inside surfaces of hoppers with antistatic cloths used in cloth dryers

A third will be to earth/ground the loading equipment. Also be aware of the Relative Humidity of the loading area. The ideal is to keep the RH between 50 and 70%. If the RH goes very low the static will become more pronounced and it might be good to invest in a humidifier. The RH must be monitored with an accurate instruments or a wet and dry ball thermometer unit (which is the most accurate).

10. What internal dimension of rifle caliber barrels affects the internal ballistics the most?

The most critical dimensions are those immediately beyond the chamber/case mouth, known as the “Freebore” and “Leade”. This is where the engraving process takes place, which determines the level of resistance which in turn “controls” the combustion process.

This is also the area that experiences the highest and most severe forces and or conditions i.e. Peak-Acceleration, Peak- Pressure and Peak-Temperatures, therefore its also the area that experiences the most erosion and wear which ultimately leads to reduced velocities of a typical worn barrel.

Any change in these dimensions can have significant and sometimes dramatic effects. If the dimensions are tight and short the pressure can rise significantly and the inverse happens when these dimensions are large/long or “loose”.

This also depends on the caliber design and its expansion ratio. If it’s a high expansion ratio caliber such as the 458WinMag 444Marlin etc the effects will be less than that of a low expansion ratio caliber also known as an “overbore” calibers such as the 264WinMag 7mmRem Mag etc. The standard calibers will fall somewhere in-between.

11. What primers should I use?

There is unfortunately no simple solution or recommendation, because the primers of different manufacturers can differ quite substantially even when rated for the same category.

However, as far as safety is concerned for the most general and popular calibers standard primers of most manufacturers will work in both the handgun and rifle categories.

The belief that all spherical powders must be combined with magnum primers is not true. This might have been the case in the early years. However, what is suggested is that as soon as the capacity of a typical rifle caliber goes beyond 70 grains it will be good to use a higher energy “Magnum” rated primer. In the case of handguns its more difficult and as far as our Accurate products is concerned it will be good to use magnum primers when the Chargemass exceeds 20grains in a typical bigger bore caliber such as 44 and larger.

As far as accuracy is concerned, which depends on the intricate/complex interactions of the components and weapon system/platform a change in any one of the major components including primers can have a significant effect, for better or worse. Therefore it will be wise to experiment with different primers if a problematic situation arises.

12. Do Magnum Primers cause higher pressures than standard primers?

Not always, and unfortunately it’s hard to predict and quantify. It depends on the combination of powder-caliber-pressure/performance level. However, in most cases the difference is small especially in the case of rifle calibers. In the case of handgun caliber certain magnum primers can cause higher pressures, however this is more the exception than the rule. Also the number of handgun calibers that really requires a magnum primer is limited to large capacity calibers using relatively slow burning powders.

There are also sometimes big differences between makes of primers which complicates the issue even further.

13. Do the same loads apply for gas-operated Semi Automatic rifles as those used with Bolt Action rifles?

The one fundamental fact and paradigm shift a semi auto or auto rifle reloader must accept and realize is that his system is more of an “engine” than the “one stroke/impulse “ action particular to single action weapon.

However, as far as safety is concerned, in most cases, the same loads will apply and therefore the -10% rule for the start load will remain.

Since semi Automatic or automatic weapons consumes energy to cycle the weapon, there are many factors that can affect this process.

  1. Some weapons have gas systems which fundamental designs are more susceptible to energy loss.
  2. The condition of the gas systems can also affect the functioning.
    1. If the physical tolerances are to loose gas leakage can reduce the effectiveness.
    2. When the system is dirty all kind of “restrictions” can lessen the efficiency of the system, such as higher friction levels or restricted gas passages and channels which impedes the gas flow.
  3. Since the time base (work) of the gas system is limited to a fraction of the total impulse time (usually below 100 micro seconds) depending on the distance between the gas port and the muzzle (muzzle exit = return to atmospheric pressure as well as “opening” the system) it does not take much to affect the functioning of such weapons.

The reloader or ammunition manufacturer must be aware of these issues and parameters and accommodate for that in the loading procedures.

No damage will occur by beginning as usual at the minimum “START” load as recommended in load guides.

The worst that can happen is insufficient energy to cycle or even partially cycle the weapon.

At worst this will manifest in a gun that will not even unlock the breech.

The next is partially unlocking without ejecting.

The next is short cycling = cases are partially ejected or ejected at low energy levels or even caught between breech and chamber.

This situation is usually easily rectified by incrementally increasing the Chargemass. The only exception will occur if there are a serious problems with the gas system, or the reciprocating breech assembly, either being “blocked” or seized up, due to some physical/mechanical issue such as high friction levels, due to improper tolerances, or being too dirty and clogged up by whatever residue .

This is were the semi auto reloader have an extra dimension to watch out for as he develops his load, and that is the level of energy observable as the cases are being ejected. This is easily quantifiable by the distance the cases are being ejected. Here an extra observer can also be of great help to determine the ejection energy level.

Also the condition of the ejected cases will show if something is wrong such as “dents” damaged or deformed case-mouths etc which might indicate a too violent action.

These signs can and will occur at different levels for different weapons even from the same manufacturer, depending on the condition of the weapon.

This condition of too high ejection energy can occur before the published maximum load or velocities are reached. If so, then this parameter must then serve as the limiting criteria for a particular weapon-ammunition combination.

If there was one basic guideline we could suggest, is that the selection of powder burn rate for a particular caliber should be such that between 92 and 100% of the case volume is used (loading density). This will ensure the best possible pressure velocity ratio and the highest gas volume and pressure at the gas port, and will result in a”well balanced” round.

However, as always there is one exception namely the M1 Garand system in 30-06 caliber, which can sometimes experience a problem by bending the operating rod if too high a gas port pressure is attained, with too slow a powder.

14. Does barrel length affect the chamber pressure?

 No the peak pressure is reached very quickly and in a short relative displacement. In the case of Rifle calibers the peak pressure is reached within 2inches of projectile movement, and in the case of handgun calibers the Peak pressure is reached while the base of the bullet is still inside the case or just at the point of leaving the case. In extremely large handgun calibers that resembles rifle calibers such as the 460S&W and the 500S&W or even larger which also utilizes extremely slow burning handgun magnum powders or even fast burning rifle powders this displacement might be ½” to 1 inch beyond the case mouth.

15. How does barrel length affect the velocity?

The barrel length does affect the velocity because, it determines time-base of the pressure/work being applied to the base of the bullet. Therefore, the longer the barrel the higher the velocity, and vice versa for shorter barrels. The proportional affect depends on the specific caliber configuration and expansion ratio. Since Rifle calibers usually have long barrels and high velocities, and handgun calibers have short barrels with lower velocities, the differences when expressed in Fps per inch can be very misleading.

It’s important to normalize and compare with the same proportions. Since the velocity change is not linear in that the velocity per length unit will be higher closer to the chamber than the muzzle, the typical figures fps/inch used can only be applied when barrels lengths are kept within the standard “length-envelope” typical to a caliber category.

The typical rifle caliber such as a 308Winchester will loose between 20 and 25 Fps per inch if kept within the approximate typical 22 to 26″ envelope. This means that the velocity will change approximately 0.9% with a 4.2% change in barrel length.

If the same proportional 4.2% change in length is applied to a typical handgun caliber, it will result in a change of between only 0.17 to 0.25 inches. Therefore a typical handgun caliber such as 9mmP at the typical length of ca 4″ will show a difference of ca 1.4% in velocity with a change of 4.2% of the barrel length. If expressed in Fps per inch it will constitute approximately 80 Fps per inch. Please keep in mind that 1 inch approximates between 20% and 25% of a typical handgun barrel length.

16. Does rifling twist affect the internal ballistics such as the peak pressure?

No, within the normal twist envelopes being used in small arms manufacturing, this effect is negligible to insignificant. The twist contributes to the stability of the projectile in flight i.e. external ballistics. A mistake which is often made is that two separate barrels are compared with different twists and when results (pressure and velocity) are obtained it is subsequently ascribed to the twist. (See question below). The only clinical way to determine the effect is to compare two identical bore groove barrels from the same base stock and then cut the chambers with the same reamer. We did this at Western powders lab and the internal ballistics were the same.

17. Why do barrels of the same caliber sometimes differ so much in velocity – especially in the case of rifle calibers?

The difference between barrels is, in most cases due to different internal dimensions of the leade/freebore area of the chamber/bore area. The bore diameter can also have a significant impact on the performance however, that happens less frequently.

18. Does the COL/AOL affect the internal ballistics?

It depends on the specific dimensions and capacity of the caliber and the proportion of the change. In the case of handgun calibers a 0.025”/1.0mm difference can have an affect as severe as 20% on the Peak pressure. However, that same amount in the case of a rifle caliber, which is much longer, will have a very small to insignificant effect.

19. Does COL/AOL affect the accuracy of rifle calibers, and does a longer dimension always result in better/improved groups?

Not always, however since the longer round sometimes improves the alignment of the round to the chamber bore axis it is a good practice to have the bullets ogive close but not touching the lands. A standoff of 0.025” to 0.050” is advised. This dimension is but one of the many parameters that can be adjusted to “tune” or optimize the accuracy of a specific combination.

20. How does case volume affect the internal ballistics?

Case volume does affect the internal ballistics, and a smaller volume will produce higher pressures and velocities, and vice versa for a larger volume at any given chargemass. However, it depends what the real difference in volume is.In the case of rifle calibers, this question are most often asked when cases are compared in the two popular calibers which are also “military” calibers i.e. Satellite pictures 223Remington/5.56mmNATO and the 308Win/7.62x51NATO.

Instead of assuming that military brass always has smaller volume, we strongly suggest that a simple volume measurement be done by filling both (or more) cases with water (preferably distilled water) and to weigh the water.

Then reduce or increase the load by the same proportion (%).

Although it can be indication, do not go by the weight of the cases.

From our recent experience the latest generation 5.56mmx45 cases have close to/or similar volumes than commercial cases. In the early years of the 5.56mmx45 ca early 1960’s, some cases were smaller in volume; however those cases have mostly been purged form the market.

In the case of 7.62×51 we have found that “MIL” cases are between 3 to 4% smaller in volume requiring a reduction in chargemass as published in our loadguides.

Please keep in mind that this applies to all calibers and when cases of different manufacturers are used we strongly recommend determining the volume with water.

21. How to load for subsonic ammunition, for RIFLE calibers:

The practice of down loading rifle calibers to subsonic velocity levels must be approached in a special way.


  • At subsonic velocities the chamber pressure is extremely low in most rifle calibers.
  • This means the combustion efficiency is not good.
  • It means that case obturation is bad.
  • Therefore faster more efficient burning powders are required.
  • This leads to low loading densities, which might cause ignition problems.
  • Because the requirement is to have subsonic velocities while maintaining the best possible combustion efficiency, the velocity should be kept as close as possible to the sonic threshold for the specific conditions, preferably between 1025 Fps to 1100 Fps.
  • Projectiles with sharp pointed ogive’s do not make good subsonic projectiles because
  • External and Terminal ballistics at subsonic velocities does not exploit the design features of high BC jacketed SP or HP-BT bullets. Therefore, it is actually a waste /moot point shooting with these designs at subsonic velocities.
  • Subsonic loads using standard components will not cycle high power, semi auto rifles.
  • Warning: — Since fast burning powders are used, it results in very low loading densities; Therefore the possibility of double charging is very high!! —— Please take extra precautions to prevent this from occurring.


  • Use only powders with good ignition characteristics.
  • Use any well-known Cast Bullet Publication, such as Lyman®, Speer® etc as a guide with the above equivalent powders. Begin at the recommended minimum/Start loads and incrementally load lower towards the subsonic range, of between 1025 and 1100 Fps.
  • In most cases extremely fast burning Handgun/Shotgun powders are the better options. However, there are exceptions involving slower burning powders with excellent ignition characteristics such as our Accurate 5744®
  • To ensure the best highest possible loading density, select the bulkiest powder with the lowest bulk density (weight/Volume).
  • Extruded flake, or -tubular or -multi perforated powders, are usually the recommended types, however there are some exceptions utilizing special spherical/Ball® powders.
  • Neck-sizing the cases to ensure proper obturation
  • Adding Fillers to keep the powder on the primer side of the case (Dacron® or Pufflon® – see below).
  • The loading is done inversely to the standard practice with normal loads and is best executed by loading from a higher Velocity usually in the 1300-1400 fps range towards the lower level.
  • Confirm statistically, with proper number of rounds per iteration (min 10 rounds) by measuring the velocity with a chronograph and verify standard deviations and extreme spreads to make absolutely sure that no supersonic “flyers” occur.
  • Make sure that projectile has left the barrel when a blackened/sooted case is extracted.
  • Also be aware when extremely low velocities are recorded < 900 Fps. This is indicative of extremely low pressures which, is an early warning sign that bad ignition "squib" loads = stuck bullet maybe eminent.
  • Use projectiles with the shortest ogive possible, preferably Round nose projectiles. This will ensure better stability due to a more centered COM (center of mass)
  • Use the heavier projectiles for a particular calibre. The higher inertia ensures better ignition and combustion.


  • Whenever inconsistent velocities are detected, it is recommended that a proper filler material be used to keep the powder at the primer end of the case.
  • The following filler materials are recommended:
    • PUFFLON®, which is a dedicated speciality filler product. www.pufflon.com
    • DACRON®. This product comes in various forms, and the “fluffy” version must be used. This must be lightly stuffed and not tightly compressed; the purpose is to merely keep the powder at the bottom of the case against the primer.

Powders recommended for subsonic loading from our own product lines:


  1. Accurate SOLO 1000®, Single base Extruded Flake
  2. Accurate Nitro100® New Formulation. Double base Spherical/Ball®
  3. Accurate no2®, Double base Spherical/Ball®.
  4. *Accurate A-5744®, Double base extruded tubular.

*Caution: This powder will leave some un-burnt powder granules behind, which can cause irritation when “flush-back” occurs into chambers and mechanisms of guns.


  1. Ramshot – Competition. Double base Spherical/Ball®