It’s the holiday season — there’s no better time to sit in front of a fire and read a good gun book. Midsouth Shooters Supply now carries the full line of shooting and reloading books from Krause Publications at very attractive prices. Looking for reliable reference works on reloading, or a gift for a shooting buddy? You’ll find something worthwhile among the Krause library of gun books, which includes the respected Gun Digest Shooter’s Guides. Match directors also take note — books make great match prizes. Paperback books cost no more than wood plaques but they will provide valuable information for years instead of just gathering dust in a closet. If your club offers training programs, Krause offers many titles that will help new shooters improve their skills.
Looking to improve your competition skills? The Shooting Sports USA website has scores of informative articles that can help your score higher at your next shooting tournament. You’ll find articles on wind reading, position shooting, match strategies, and much more.
One great Shooting Sports USA article, Shooting is 90% Mental, was penned by Chip Lohman (SSUSA’s former Editor). With the help of two very smart Ph.D types, Judy Tant and Mike Keyes, Lohman examines the mental processes involved in the shooting sports. Chip’s co-authors have impressive credentials. Dr. Judy Tant is a Clinical Psychologist and National Bullseye Pistol Champion. Dr. Michael J. Keyes, is a licensed Psychiatrist and former physician for the U.S. Shooting Team.
Visualization, Brain Function, and Muscle Memory
If you shoot competitively, this is definitely a “must-read” article. The authors examine how the brain functions under stress, how “visualization” can be used to improved performance, how “brain speed” can be enhanced through proper training, and how the brain stores learned routines into “muscle memory.” And that’s just for starters — the article gives many concrete examples of techniques top shooters have employed to improve their “mental game” and shoot higher scores.
Brain Speed and Trigger Control: Research: Scientists believe that the newer frontal lobe may not be able to keep up with “deep” brain signals that transmit at nearly 300 mph. This is explained when athletes talk about “letting go”, rather than over-thinking the shot.
This conscious signal can take up to 0.3 seconds from recognizing the desired sight picture to moving the trigger finger — too long to capture the opportunity for a perfect shot. However, if the signal is initiated spontaneously in the cerebellum where such procedures are thought to be stored through repetition, the reaction speed is much quicker. Signals are processed by the “deep brain” almost twice as fast as the problem-solving frontal lobes.
The First Shot, the CMP’s online magazine, features a well-written article on Prone Shooting Technique by SPC Matthew Sigrist of the U.S. Army Marksmanship Unit (USAMU). The article covers all the major points of gun hold and body position: hand position, elbow position, stock weld, buttstock placement, and sling position/tension.
Keep it Steady — The Elements of a Good Prone Position
Part 1 — Building the Position By SPC Matthew Sigrist
Imagine the following scenario: You are at the last stage of fire in the National Trophy Individual Match, firing at the 600 yard line in the prone position and every point matters. What should you reflect on as you prepare to shoot this final string? As your eyes cloud from sweat, you realize that all you have to rely on is your experience and knowledge of the fundamentals.
During the National Trophy Individual Match, you will fire 60 percent of your shots from the prone position. This article will address the fundamentals of a good prone position and help you learn the techniques required to be successful in both the slow and rapid-fire stages of National Match competition.
This article will be divided into two parts. In part one, we will discuss the elements of a good prone position. In part two, we will cover the techniques you will in the rapid-fire and slow-fire stages.
The Fundamentals
The fundamentals are the building blocks of a position. Much like the framework of a house, a correct application of the fundamentals ensures a solid and stable structure. Since each person’s position will depend on their particular body build and shape, there is no “perfect position” that applies to everyone. Experience, practice and knowledge of the correct fundamentals will dictate the best position for you.
There are six key elements of any position. The purpose for these six points is to achieve a solid platform that allows for consistent sight alignment using the least amount of muscle tension.
1. Placement of the Firing Hand (the hand that pulls the trigger)
The firing hand needs to be placed high on the pistol grip. This high hand position will give you better control of the rifle. Combined with a firm grip there will be a reduced amount of hand movement when pulling the trigger. Wrap your thumb over the three fingers on the pistol grip (excluding the trigger finger). This will help isolate the movement of the trigger finger.
2. Placement of the Non-firing Hand (the hand supporting the rifle).
The non-firing hand should grip the handguard or stock in the flat portion of the hand between the thumb and forefinger. The fingers should curl naturally around the stock, but they should not grip it tightly. The position of the hand on the stock will depend on the physical size of the shooter. Generally speaking, taller shooters with longer arms will grip the rifle further out, near the sling swivel, while shorter shooters will need to pull their hand rearward. This is sometimes referred to as “short-stocking” the rifle.
3. Stock Weld
Stock weld is the contact that the face makes with the stock. It is important because it directly effects your sight alignment. Consistent head placement will help you achieve consistent sight alignment. The human head weighs an average of 8 to 10 pounds. The full weight of the head must rest on the stock. In doing this you achieve two things, a relaxed neck and reduced recoil because of the pressure of the head.
4. Placement of the Rifle (the contact that is made in the firing shoulder)
The rifle butt placement needs to be consistent. If this changes between shots, it effects your sight alignment and the effect of recoil. In the prone position the rifle will sit lower in the shoulder compared to other shooting positions. This allows for a more forward head and a lower position as a whole.
5. Position of the Sling
The sling should be high on the arm, above the bicep. This way the sling will have less leverage on the arm so it doesn’t cut off the circulation.
Demonstration of the placement of the firing elbow (left) and non-firing elbows (right).
6. Placement of both the firing, and non-firing elbows
A guideline for non-firing elbow placement is that there should be 1 ½’’ to 2’’ gap between your non-firing arm and the rifle’s magazine. (NOTE: this references the AR-15 service rifle) Your arm should be almost straight up and down; this will transfer the weight directly down the arm and not to the side (see picture above). Think of the firing arm as only a kind of kickstand, it doesn’t support weight it only holds the firing hand in position.
Variations of the Prone Position
There are two main variations of the prone position; open/spread legged, and bent-legged. The two types will be discussed below.
Open/Spread Leg Position
Demonstration of the Open/Spread Leg Position.
The first position is the open/spread legged position. This is when the shooter spreads their legs shoulder width or more apart. This allows for a more forward pressure on the sling and elbows. This position requires a tighter sling and solid elbow placement. The rifle should sit tight in the shoulder. With this position, your body will be farther behind the rifle compared to the bent leg position, allowing for minimum disturbance from recoil.
Bent Leg Position
Demonstration of the Bent Leg Position.
The bent leg position is when the shooter bends the firing side leg up towards the firing hand making the knee at a rough 90 degree angle to the body. The non-firing leg will remain straight and inline with the body. This will take pressure off the lungs and heart minimizing the pulse from the chest as well as easing the pressure on the lungs which will allow for easy breathing and control.
Summary
You now know the fundamentals of a good prone position, as well as the two types most commonly used. Extensive dry-firing will reveal which is the best position for you. If possible, have a friend take pictures of you in position. This will enable you to better diagnose and correct your errors. Remember, a position must be both fundamentally sound and comfortable. Practice frequently to learn your new position and to develop the conditioning required to endure long days on the range.
At the request of Forum members, we are reproducing this helpful article by gunsmith and Hall-of-Fame benchrest shooter Thomas “Speedy” Gonzalez
How to Reduce Vertical in Your Shot Groups
One of our Shooter’s Forum members recently built a new benchrest rifle. He was concerned because his groups were stringing vertically. This is a common problem that all precision shooters will face sooner or later. In addition to ammo inconsistencies, many other factors can cause vertical stringing. Accordingly, it’s important that you analyze your gun handling and bench set-up systematically.
Hall of Fame benchrest Shooter Speedy Gonzalez has written a helpful article that explains how to eliminate mechanical and gun-handling problems that cause vertical spread in your groups. Speedy’s article addresses both the human and the hardware factors that cause vertical. CLICK HERE to read the full article. Here are a few of Speedy’s tips:
• Front Bag Tension — Vertical can happen if the front sand bag grips the fore-arm too tightly. If…the fore-arm feels like it is stuck in the bag, then the front bag’s grip is too tight. Your rifle should move in evenly and smoothly in the sand bags, not jerk or chatter when you pull the gun back by hand.
• Sandbag Fill — A front sandbag that is too hard can induce vertical. Personally, I’ve have never had a rifle that will shoot consistently with a rock-hard front sandbag. It always causes vertical or other unexplained shots.
• Stock Recoil — Free-recoil-style shooters should be sure their rifle hits their shoulder squarely on recoil, not on the edge of their shoulder or the side of their arm. If you shoulder your gun, you need to be consistent. You can get vertical if your bench technique is not the same every shot. One common problem is putting your shoulder against the stock for one shot and not the next.
• Front Rest Wobble — You will get vertical if the top section of the front rest is loose. Unfortunately, a lot of rests have movement even when you tighten them as much as you can. This can cause unexplained shots.
• Stock Flex — Some stocks are very flexible. This can cause vertical. There are ways to stiffen stocks, but sometimes replacement is the best answer.
• Rifle Angle — If the gun is not level, but rather angles down at muzzle end, the rifle will recoil up at butt-end, causing vertical. You may need to try different rear bags to get the set-up right.
• Unbalanced Rifle — If the rifle is not balanced, it does not recoil straight, and it will jump in the bags. If the rifle is built properly this will not happen. Clay Spencer calls this “recoil balancing”, and he uses dual scales (front and rear) to ensure the rifle recoils properly.
• Firing Pin — A number of firing-pin issues can cause vertical. First, a firing pin spring that is either too weak or too strong will induce vertical problems. If you think this is the problem change springs and see what happens. Second, a firing pin that is not seated correctly in the bolt (in the cocked position) will cause poor ignition. Take the bolt out of rifle and look in the firing pin hole. If you cannot see the entire end of firing pin it has come out of the hole. Lastly, a firing pin dragging in bolt or shroud can cause vertical. Listen to the sound when you dry fire. If you don’t hear the same sound each shot, something is wrong.
• Be Consistent — You can get vertical if your bench technique is not the same every shot. One common problem is putting your shoulder against the stock for one shot and not the next.
• Head Position — Learn to keep your head down and follow-through after each shot. Stay relaxed and hold your position after breaking the shot.
• Last Shot Laziness — If the 5th shot is a regular problem, you may be guilty of what I call “wishing the last shot in”. This is a very common mistake. We just aim, pull the trigger, and do not worry about the wind flags. Note that in the photo below, the 5th shot was the highest in the group–probably because of fatigue or lack of concentration.
Tomorrow is October 31st, Halloween (originally called “All Hallows’ Evening”). That means kids in costumes will be ringing doorbells as soon as it gets dark. No doubt some of you proscrastinators will wait ’til the last minute to set out your Halloween decorations and Jack-O-Lanterns. Don’t worry, in the video below, our friend, 3-Gun ace Taran Butler, shows how to carve a pumpkin in just about 5.5 seconds, give or take a tenth. Taran performed this feat of speed-carving with his trusty Infinity handgun, chambered in 9mm Major.
What Are the Origins of Halloween?
Halloween or Hallowe’en (a contraction of “All Hallows’ Evening”), also known as All Hallows’ Eve, is a yearly celebration observed on October 31, the eve of the Western Christian feast of All Hallows (or All Saints). According to many scholars, it was originally influenced by western European harvest festivals and festivals of the dead with possible pagan roots, particularly the Celtic Samhain. Others maintain that it originated independently of Samhain and has Christian roots.
Many of our readers are thinking of trying out PRS-type competition. Tactical matches are becoming more popular every season. Along with F-Class, tactical/practical disciplines are the fastest-growing forms of competitive rifle shooting. Rich Emmons, one of the founders of the Precision Rifle Series (PRS), has written an insightful article about getting started in the tactical game. This will help PRS novices pick the right equipment and understand the game. Here are highlights from Emmon’s “PRS — Intro to Competition” article, originally published on the PRS website. You may also want to read the current PRS FAQ Page.
Precision Rifle Series — Intro to Competition
by Rich Emmons, PRS President
Tactical Shooting with a precision rifle is not like other disciplines, there is no set course of fire or format. That is what makes it so fun!
First, you have to ask yourself what do you want to accomplish. When I was introduced to long range shooting, immediately a light turned on for me, once I saw how easy it was to hit 300–600 yard targets. What I quickly learned from my first competition and the many that followed was there is so much to learn and shooting in competition put everything you thought you knew to the test. So back to the question: “What do YOU want to accomplish?”. The reality is you may not know yet, you just think it is cool to have a bad ass rifle and scope that can make almost any shot. Now if you’ve got that rifle and scope, it’s time to take it to the next level.
Watch PRS 2016 Championship
Getting Started — What to Expect
If you’re reading this, you have probably already have been bitten by the long range shooting bug. It can seem quite intimidating to just jump in with a new bunch of shooters you don’t know and shooting lingo you don’t quite understand yet. But here is the key — show up and shoot! I guarantee you if you show up to a match as a new shooter, other experienced shooters will guide you along and give you help on anything you need.
AUDIO: Click Button to hear Rich Emmons Talk about the Precision Rifle Series.
Now, a couple things you should just expect. You’re not as good as you think you are. Don’t expect to come into your first match and beat all the veterans. That just doesn’t happen unless you have had some really good coaching or other shooting competition experience to get you ready for this type of competition. If possible, find a local rifle club that has monthly long range matches, or any type of match will help prepare you for a larger PRS event. Getting involved with a rifle club and starting out shooting monthly matches is definitely the way to jump into competition shooting.
The Gear You Need
The first question that many ask is: “What kind of rifle/caliber/scope do I need?” The easiest answer to this is, the best you can afford. It’s no secret the gear is expensive. It took me several years of buying sub-par gear and eventually trading up to figure this out. Now, a guy can get a real sense of pride of doing it on the cheap, or with a factory rifle. I’ve seen many old Savage 10FPs take down custom rigs that cost 10 times as much. And if that’s all you can afford, then eventually you will learn the limitations of yourself or your gear. As for choice of cartridge/caliber, the respected Precision Rifle Blog has analyzed four years worth of match results from the best tactical shooters in the nation. CLICK HERE to read a PRB article that reveals what the “top guns” use.
Craig Arnzen of Area 419 has created a useful article reviewing the gear PRS shooters need, including support bags, hearing protection, and other key accessories such as muzzle brakes. This helpful article also covers factory ammunition options.
Making Good Ammo
Producing quality reloads is something you have to master. It’s not hard at all, you just have to pay attention to detail, and eventually you are going to do something stupid like mis-priming your brass, or skip a row of brass when dumping your powder. Everybody has their own horror story of some reloading failure that cost them a stage or even a match. So load to perfection, work with your rifle to find what load it likes the best, then start your practice.
Practice Makes Perfect
You want to become ONE with your rifle, learning everything you can about its functionality. Getting comfortable with the operation of your rifle is key. Learn the feel of your trigger, dry-firing until you wear the paint off your bolt handle. Learn how the rifle works best — pay attention to little things like the sound and feel of the bolt feeding a round from the mag (or when it doesn’t). Learn how to remove a jammed round quickly, learn how to reload a magazine quickly. Learn to scan across a field and find targets in a quick manner, seeing the targets with your eye and coming into the scope on target. These are some of the basic practices that separate the new shooters from the seasoned ones.
Here’s a cool contest courtesy of Pyramyd Air. Win a pick-your-own prize package worth up to $3000.00. The winner selects any combination of products from Pyramyd Air’s entire inventory — air rifles, scopes, pellets, targets — you name it. You can even choose a set of products that cost more than $3000 — you just pay the difference. Act soon — the entry deadline is November 10, 2018.
This Backyard Brawl contest is a bit unusual. To enter you need to shoot a set of mini silhouettes and then make a video. The silhouette targets are free with code BRAWLER (shipping extra). Once you receive the targets, knock ‘em down with your airgun, and upload a video to YouTube or Vimeo.
How to Enter Backyard Brawlin’ Contest
Order Air Venturi Airgun Slynger Metal Silhouette Targets, FREE with promo code BRAWLER (shipping extra). Then upload a video of you shooting the targets with an air rifle or air pistol. Contest ends November 10, 2018. Limit one entry per person. All entrants will receive $5 in Bullseye Bucks at Pyramyd Air. Winner will be announced the week of November 12, 2018.
Backyard Brawl Contestant Videos
Here are two videos recently uploaded by Backyard Brawl contest entrants. You’ll see some pretty good shooting with interesting airguns. Can you make a more entertaining video?
Here Matt Coulter shoots a .22 Caliber Royale with JSP Express Jumbo pellets at about 580 fps.
In this video, UpNorthAirGunner shoots a Benjamin Marauder .177 Field & Target, a Broom-Handle Mauser clone full-auto BB Pistol, and a Seneca “Dragon Claw” .50 caliber air rifle.
If you buy one book about Long Range Shooting, this should be it. Based on sophisticated testing and research, this 356-page hardcover from Applied Ballistics offers important insights you won’t find anywhere else. Modern Advancements in Long Range Shooting – Volume II, the latest treatise from Bryan Litz, is chock full of information, much of it derived through sophisticated field testing. As Chief Ballistician for Berger Bullets (and a trained rocket scientist), author Bryan Litz is uniquely qualified. Bryan is also an ace sling shooter and a past F-TR National Champion. Moreover, Bryan’s company, Applied Ballistics, has been a leader in the Extreme Long Range (ELR) discipline.
AUDIO FILE: Bryan Litz Talks about Modern Advancements in Long Range Shooting, Volume 2. (Sound file loads when you click button).
Volume II of Modern Advancements in Long Range Shooting ($39.95) contains all-new content derived from research by Applied Ballistics. Author Bryan Litz along with contributing authors Nick Vitalbo and Cal Zant use the scientific method and careful testing to answer important questions faced by long range shooters. In particular, this volume explores the subject of bullet dispersion including group convergence. Advanced hand-loading subjects are covered such as: bullet pointing and trimming, powder measurement, flash hole deburring, neck tension, and fill ratio. Each topic is explored with extensive live fire testing, and the resulting information helps to guide hand loaders in a deliberate path to success. The current bullet library of measured G1 and G7 ballistic coefficients is included as an appendix. This library currently has data on 533 bullets in common use by long range shooters.
Bryan tells us that one purpose of this book is to dispel myths and correct commonly-held misconceptions: “Modern Advancements in Long Range Shooting aims to end the misinformation which is so prevalent in long range shooting. By applying the scientific method and taking a Myth Buster approach, the state of the art is advanced….”
Bullet Dispersion and Group Convergence
Part 1 of this Volume is focused on the details of rifle bullet dispersion. Chapter 1 builds a discussion of dispersion and precision that every shooter will benefit from in terms of understanding how it impacts their particular shooting application. How many shots should you shoot in a group? What kind of 5-shot 100 yard groups correlate to average or winning precision levels in 1000 yard F-Class shooting?
Chapter 2 presents a very detailed investigation of the mysterious concept of group convergence, which is the common idea that some guns can shoot smaller (MOA) groups at longer ranges. This concept is thoroughly tested with extensive live fire, and the results answer a very important question that has baffled shooters for many generations.
Part 2 of this Volume is focused on various aspects of advanced hand-loading. Modern Advancements (Vol. II) employs live fire testing to answer the important questions that precision hand loaders are asking. What are the best ways to achieve MVs with low ES and SD? Do flash hole deburring, neck tension, primer selection, and fill ratio and powder scales sensitivity make a difference and how much? All of these questions are explored in detail with a clear explanation of test results.
One of the important chapters of Part 2 examines bullet pointing and trimming. Applied Ballistics tested 39 different bullet types from .224 through .338 caliber. Ten samples of each bullet were tested for BC in each of the following configurations: original out of the box, pointed, trimmed, pointed and trimmed. The effect on the average BC as well as the uniformity in BC was measured and tabulated, revealing what works best.
Part 3 covers a variety of general research topics. Contributing author Nick Vitalbo, a laser technology expert, tested 22 different laser rangefinders. Nick’s material on rangefinder performance is a landmark piece of work. Nick shows how shooters can determine the performance of a rangefinder under various lighting conditions, target sizes, and reflectivities.
Chapter 9 is a thorough analysis of rimfire ammunition. Ballistic Performance of Rifle Bullets, 2nd Edition presented live fire data on 95 different types of .22 rimfire ammunition, each tested in five different barrels having various lengths and twist rates. Where that book just presented the data, Chapter 9 of this book offers detailed analysis of all the test results and shows what properties of rimfire ammunition are favorable, and how the BCs, muzzle velocities and consistency of the ammo are affected by the different barrels.
Chapter 10 is a discussion of aerodynamic drag as it relates to ballistic trajectory modeling. You will learn from the ground up: what an aerodynamic drag model is, how it’s measure and used to predict trajectories. Analysis is presented which shows how the best trajectory models compare to actual measured drop in the real world.
Finally, contributing author Cal Zant of the Precision Rifle Blog presents a study of modern carbon fiber-wrapped barrels in Chapter 11. The science and technology of these modern rifle barrels is discussed, and then everything from point of impact shift to group sizes are compared for several samples of each type of barrel including standard steel barrels.
Have you ever wondered how Olympic-class position shooters hold their aim so steady? Those bulky shooting coats help, but there is a lot of bio-mechanics involved also. Top shooters employ their body structure to help support the weight of their rifles, and to steady their aim. This interesting video, produced by GOnra Media, demonstrates rifle hold and body alignment for prone, standing, sitting, and kneeling positions. Olympic Gold Medalist Jamie Corkish (formerly Jamie Gray) demonstrates the proper stance and position of arms and legs for each of the positions. Ideally, in all of the shooting positions, the shooter takes advantage of skeletal support. The shooter should align the bones of his/her arms and legs to provide a solid foundation. A shooter’s legs and arms form vertical planes helping the body remain stable in the shooting position.
Jamie Corkish, London 2012 Gold Medalist in Women’s 3 X 20, has retired from top-level competitive shooting. However, Jamie remains involved in the shooting sports as a Public Relations/Marketing representative for ELEY, a leading maker of rimfire ammunition. Jamie also works with shooting clubs and educational institutions to promote smallbore target shooting.
Images are stills from GOnraMedia video linked above.
On LongRangeHunting.com, you’ll find a good article by Shawn Carlock about wind reading. Shawn is a veteran law enforcement marksman and a past USPSA national precision rifle champion. Shawn offers good advice on how to estimate wind speeds and directions using a multitude of available indicators — not just your wind gauge: “Use anything at your disposal to accurately estimate the wind’s velocity. I keep and use a Kestrel for reading conditions….The Kestrel is very accurate but will only tell you what the conditions are where you are standing. I practice by looking at grass, brush, trees, dust, wind flags, mirage, rain, fog and anything else that will give me info on velocity and then estimate the speed.”
Shawn also explains how terrain features can cause vertical wind effects. A hunter on a hilltop must account for bullet rise if there is a headwind blowing up the slope. Many shooters consider wind in only one plane — the horizontal. In fact wind has vertical components, both up and down. If you have piloted a small aircraft you know how important vertical wind vectors can be. Match shooters will also experience vertical rise when there is a strong tailwind blowing over an up-sloping berm ahead of the target emplacements. Overall, Shawn concludes: “The more time you spend studying the wind and its effect over varying terrain the more successful you will be as a long-range shooter and hunter.”
This Editor, as a life-long sailor, also has some suggestions about wind. Many folks may not realize that wind can cycle, both in direction and in speed (velocity). If you are patient, you should be able to sense the timing of the cycles, which will help you predict shifts in wind direction and velocity. While it is tempting to shoot in the lulls, sometimes the true wind vector (angle + speed) may be most constant when the wind is blowing stronger.
Another tip for hunters is to orient your shot, when possible, in alignment with the wind direction. Try to face into the wind, or have the wind at your back. This is especially effective when shooting in a varmint field. Use a string of tape on a pole to show wind angle. Then shoot directly into the wind or with the wind directly at your back. This will minimize horizontal deflection caused by the wind.
Research: Scientists believe that the newer frontal lobe may not be able to keep up with “deep” brain signals that transmit at nearly 300 mph. This is explained when athletes talk about “letting go”, rather than over-thinking the shot.
• Front Bag Tension — Vertical can happen if the front sand bag grips the fore-arm too tightly. If…the fore-arm feels like it is stuck in the bag, then the front bag’s grip is too tight. Your rifle should move in evenly and smoothly in the sand bags, not jerk or chatter when you pull the gun back by hand.
Tomorrow is October 31st, Halloween (originally called “All Hallows’ Evening”). That means kids in costumes will be ringing doorbells as soon as it gets dark. No doubt some of you proscrastinators will wait ’til the last minute to set out your Halloween decorations and Jack-O-Lanterns. Don’t worry, in the video below, our friend, 3-Gun ace 
Part 2 of this Volume is focused on various aspects of advanced hand-loading. Modern Advancements (Vol. II) employs live fire testing to answer the important questions that precision hand loaders are asking. What are the best ways to achieve MVs with low ES and SD? Do flash hole deburring, neck tension, primer selection, and fill ratio and powder scales sensitivity make a difference and how much? All of these questions are explored in detail with a clear explanation of test results.
