Rifle accuracy is pointless unless you can see your target and aim precisely. That’s why good optics are so important for precision shooting — from 50 yards out to a mile and beyond. Top quality scopes can be very expensive — you’ll see optics costing $3000 or more on many competition F-Class and PRS rifles. Today’s video showcase covers important “Riflescope Knowledge”, including how to adjust for parallax, and how to properly sight-in your scoped rifle. In addition there’s a helpful video defining Minute of Angle (MOA) plus videos showing how to mount optics correctly (and avoid common scope-mounting mistakes).
Rifle Sight-In Process — Start to Finish
Here Ryan Cleckner shares his process for sighting in a scoped rifle. This helpful video covers the full process: bore-sighting, 25-yard shot confirmation, shooting groups, making adjustments at 100 yards, and finding mechanical zero. Looking for more valuable rifle instruction? Then check out Ryan Cleckner’s book, Long Range Shooting Handbook.
How to Adjust for Parallax
Most precision rifle scopes have parallax adjustment, but what is it and why do you need to adjust it? In this Shooting USA video, John Paul of JP Rifles defines parallax and explains why you need to set parallax correctly for the distance to your target. The video then show how to adjust parallax correctly, a process which should start with the scope’s ocular focus.
Understanding Minute of Angle (MOA)
In this video, Ryan Cleckner explains the measurement term “minute of angle” (MOA) and how to use MOA adjustments on your scope to compensate for bullet drop at varying distances. MOA is an angular measurement, used often in long range shooting, that is 1/60th of one degree of a circle. One MOA represents 1.047″ at 100 yards and 10.47″ at 1000 yards. Want to learn more? Read Ryan Cleckner’s article Understand and Using Minute of Angle.
Scope Mounting: Common Scope-Mounting Mistakes To Avoid
Mounting a scope isn’t a super-complex or highly technical job, but there are ways you can mess it up. This Brownells video explains common pitfalls to avoid when you’re mounting a rifle scope.
1. Make sure the rings don’t touch any part of the turret housing, objective bell, or eyepiece. Any one or combination of those will throw off your shot groups big time. Make sure those rings are clamping ONLY the scope’s main tube.
2. Ensure that the scope rings are properly clamped to the scope base. If you can grasp the scope with one hand and the rifle with the other and there’s play between them, your groups are going to be all over the place! Scope rings come with torque specs for a reason.
3. Make sure there’s clearance between the objective bell and the rifle. No part of the scope should touch the rifle itself. The only nexus between the scope and the rifle should be the scope rings — and they’re not actually part of the rifle. This also applies to a removable lens cover. When it’s on the scope, it should not touch any part of the gun.
4. Don’t mount the scope too low on an AR-15. On most rifles, you do want the centerline of the optic as close to the bore as you can get it. But the AR-15’s stock is on almost the same plane as the top of the receiver, so you need some height on the scope. Otherwise, it’ll be too low for you to look through it.
5. Overtightening the scope rings is VERY BAD. You can actually crush the scope tube and damage the optic beyond repair. Stick to those torque specs! If the rings come with a little wrench, that wrench is all you need to tighten them.
How to Sight In a Riflescope — Vortex Tech Talk
This popular video from Vortex Optics explains how to sight-in a rifle so that the reticle is aligned correctly and the scope is zeroed properly for your intended application/discipline. People need to remember that the sight height established by the rings will affect their zero, as the centerline of the scope is above the centerline of the barrel.
Scope Mounting — Proper Alignment and Torque Values
An improperly installed scope can cost you points at a match. In this video, MDT Pro Shooter Keith Baker explains the simple steps required to ensure your scope is secured properly with the reticle aligned correctly. The video centers on a typical Precision Rifle PRS/NRL optics installation, but the techniques will also work for hunting, varmint, and benchrest rifles.
Share the post "Saturday Movies: Six Flicks about Scope Operation and Mounting"
With barrels, one wonders “Can a little more length provide a meaningful velocity gain?” To answer that question, Rifleshooter.com performed an interesting test, cutting a .308 Win barrel from 28″ all the way down to 16.5″. The cuts were made in one-inch intervals with a rotary saw. At each cut length, velocity was measured with a Magnetospeed chronograph. To make the test even more interesting, four different types of .308 Win factory ammunition were chronographed at each barrel length.
This is a very useful test is you’re thinking about building a .308 Win hunting rifle, or perhaps thinking of going shorter for your F-TR rifle to save weight.
Test Barrel Lost 22.7 FPS Per Inch (.308 Win Chambering)
How much velocity do you think was lost, on average, for each 1″ reduction in barrel length? The answer may surprise you. With a barrel reduction from 28″ to 16.5″, the average speed loss of the four types of .308 ammo was 261 fps total. That works out to an average loss of 22.7 fps per inch. This chart shows velocity changes for all four ammo varieties:
Summary of Findings:
The average velocity loss per inch, for all four ammo types combined, was 22.7 FPS. By ammo type, the average FPS loss per inch was: 24.6 (Win 147 FMJ), 22.8 (IMI 150 FMJ), 20.9 (Fed GMM 168gr), and 22.5 (Win 180PP).
Interestingly, these numbers jive pretty well with estimates found in reloading manuals. The testers observed: “The Berger Reloading manual says for the 308 Winchester, ‘muzzle velocity will increase (or decrease) by approximately 20 fps per inch from a standard 24″ barrel’.”
How the Test Was Done
The testers described their procedure as follows: “Ballistic data was gathered using a Magnetospeed barrel mounted ballistic chronograph. At each barrel length, the rifle was fired from a front rest with rear bags, with five rounds of each type of ammunition. Average velocity and standard deviation were logged for each round. Since we would be gathering data on 52 different barrel length and ammunition combinations and would not be crowning the barrel after each cut, we decided to eliminate gathering data on group sizes. Once data was gathered for each cartridge at a given barrel length, the rifle was cleared and the bolt was removed. The barrel was cut off using a cold saw. The test protocol was repeated for the next length. Temperature was 47° F.”
CLICK HERE to Read the Rifleshooter.com Test. This includes detailed charts with inch-by-inch velocity numbers, multiple line charts, and complete data sets for each type of ammo. Rifleshooter.com also offers ballistics graphs showing trajectories with different barrel lengths. All in all, this was a very thorough test by the folks at RifleShooter.com.
Much Different Results with 6mmBR and a Longer Barrel
The results from Rifleshooter.com’s .308 barrel cut-down test are quite different than the results we recorded some years ago with a barrel chambered for the 6mmBR cartridge. When we cut our 6mmBR barrel down from 33″ to 28″, we only lost about 8 FPS per inch. Obviously this is a different cartridge type, but also our 6mmBR barrel start length was 5″ longer than Rifleshooter.com’s .308 Win start length (and we ended where Rifleshooter’s .308 started — at 28″). Velocity loss can be more extreme with shorter barrel lengths (and bigger cartridges). Powder burn rates can also make a difference.
Share the post "How .308 Win Velocity Changes with Barrel Cut from 28″ to 16.5″"
by Sierra Bullets Ballistic Technician Paul Box
All of us who have been in reloading and shooting for any period of time have read how sectional density has been regarded as a bullet’s ability to penetrate. Back before high velocity came along and modern bullet design, the easiest way to get more “power” and penetration was by increasing the diameter and mass. After all, a bowling ball will hurt more than a golf ball, right?
Let’s take a closer look at sectional density.
The formula for calculating sectional density is pretty simple and straight forward. Take the bullet weight and divide by 7000. This number is then divided by the bullet diameter squared Two bullets of equal weight and the same diameter will have equal sectional sectional density. No regard is given to the bullet construction. This is where the fly hits the soup in considering sectional density as far as penetration is concerned.
Section Density Formula: (Bullet Weight divided by 7000) divided by Bullet Diameter squared.
Bullet construction is the biggest factor in how it is able to penetrate. The best example I can think of here is to look at the Sierra .224 55 Gr. FMJBT GameKing #1355 compared to the 55 Gr. BlitzKing #1455. Both are .224 and weigh 55 grs. Both have a sectional density of .157. But there is a huge difference in their construction. The FMJ has a thick jacket and is designed to penetrate. The BlitzKing is designed for fast and rapid expansion with little concern for how deep they will penetrate.
The next time you’re choosing a bullet, look at the construction and less at the sectional density number. It’s all about the construction anyway. If you have any questions or would like to discuss sectional density or bullet penetration further, please give us a call at 800-223-8799 or shoot us an email at sierra@sierrabullets.com.
Share the post "Sectional Density of Bullets — What You Need to Know"
Here’s something all shooters need — a smartphone App that calculates bullet-hole group sizes from your own photos. The Ballistic-X App is simple to use. Take a photo of your target, set some values (such as bullet diameter and distance to target), then use the touchscreen to place circles around each hole. The App will calculate group size (in MOA or Mils), distance to point of aim, and provide all the info in an overlay. Then click “save” to record your group for posterity!
This App works well, is relatively easy to set-up, and costs just $7.99. It is available for both Android devices and iOS (Apple) devices. There are other ways to measure group sizes from target images, such as the excellent On-Target program, which we have used for years. However On-Target requires a software installation on a Windows platform desktop or laptop. Ballistic-X is a simple, easy-to-install App with versions for both Android and iOS (Apple) Mobile devices.
The Ballistic-X App has a relatively easy-to-use interface. Of course you can choose either MOA or Milrad group values, and Inch or Metric dimensions. There are various labeling options that provide useful info for Load Development. There is even an ATZ (Adjustment To Zero) feature for adjusting your turrets.
How to Use Ballistic-X App
1. Select Photo Source — Choose Camera to take new photo or get image from Photo Library.
2. Set Reference Values — Select Bullet Diameter and enter Distance to Target.
3. Establish Scale on Image — Mark two points on target photo to set scale. For example, if the target has a 1″-square grid lines, mark two points on grid for 1″ distance.
4. Mark Point Of Aim — Put the central X on the aim point.
5. Designate Shot Locations — Place the green circles around each shot.
6. Finalize Data Display — Position Overlay, select size/color options, and export file.
Android Options — Range Buddy FREE App
Along with Ballistic-X, there is another Mobile App, Range Buddy, that also measures shot groups. Range Buddy is currently offered for Android devices only. It is FREE, but has adverts. Range Buddy isn’t bad, but users complained about the program crashing, and there are compatibility issues with newer phones. We recommend you pay $7.99 and stick with Ballistic-X.
Share the post "Measure Group Sizes Quickly and Precisely with Ballistics-X App"
Do you know which one of your eyes is dominant? It’s easy to determine eye dominance with a simple exercise. Pick an object about 6-10 feet away (a light switch or door knob works well). Make an “OK” sign with your right hand (see photo) and hold that about 18″ from your face. Now, with both eyes open, look through the circle formed by your thumb and index finger. Center the circle on the object, so you can see the object in the middle.
Now, here’s the important part — while still holding your hand up, centered on the object, first close your right eye. If you don’t see the object anymore, then your right eye is dominant. If you still see the object, then repeat the procedure with the left eye shut and right eye open. If you don’t see the object when your left eye (only) is closed, then you are left-eye dominant.
The digital archives of Shooting Sports USA contain many interesting articles. A while back, Shooting Sports USA featured a “must-read” expert Symposium on Eye Dominance, as it affects both rifle and pistol shooting. No matter whether you have normal dominance (i.e. your dominant eye is on the same side as your dominant hand), or if you have cross-dominance, you’ll benefit by reading this excellent article. The physiology and science of eye dominance is explained by Dr. Norman Wong, a noted optometrist. In addition, expert advice is provided by champion shooters such as David Tubb, Lones Wigger, Dennis DeMille, Julie Golob, Jessie Harrison, and Phil Hemphill. NOTE: If the story doesn’t open at the links, go to the ssusa.org home page first, indicate you are over 18, and then CLICK HERE.
Top Rifle Champions Talk About Eye Dominance:
David Tubb — 11-Time National High Power Champion
I keep both eyes open, always. Some use an opaque blinder in rifle or shotgun shooting. If you close your non-dominant eye, you will not get as good a sight picture. If your aiming eye is not your dominant eye, you have even more of a problem to overcome.
Lones Wigger — World, National and Olympic Champion Rifleman
Shooters should try to use the dominant eye unless the vision is impaired and the non-dominant eye has better vision. You should always shoot with both eyes open since this will allow the shooting eye to function properly.
Dennis DeMille — National Service Rifle Champion
I close my non-shooting eye initially. Once I pick up my sight picture, it’s not something I focus on. For those that use a patch, I recommend that they use something white to block their view, rather than cover the eye.
Bruce Piatt — 2015 World Shooting Championship Winner
Some shooters, especially those with nearly equal or cross-dominance, will naturally find themselves squinting one eye. When anyone does this, you are also closing your dominant eye to some extent and adding stress to your face.
Share the post "Quickly Determine Your Dominant Eye with This Simple Test"
From time to time, we all encounter a primer that doesn’t go off. It’s normal to attribute the problem to a bad primer. But sometimes there are other explanations. George S., one of our Forum members, experienced a couple failures to fire, but he learned that the issue was his priming TOOL, not his primers. Here’s what George told us. There’s a lesson to be learned:
“I had issues with CCI 450s when I had my first 6BR barreled. I had probably three or four out of 20 rounds that failed to fire. the primers were dented but didn’t fire. I called CCI since I had bought a case of them. The tech was decent enough but had the audacity to tell me I was not seating the primers all the way in the pocket. I proceeded to let him know I had been reloading longer than he had been alive and I knew how to seat a primer.
Turns out that I did and I didn’t! I was using the RCBS primer tool I had used for years and the primers felt just fine to me. I finally decided to check the tool and since I had a new one I took the seating pins out and measured them. The seating pin on the tool I had been using for years was shorter by a few thousandths! I then used the pin from the new primer tool and darned if the primers that didn’t seat down to the bottom of the cup.
I switched to a K&M primer tool for seating the CCI primers and have not had a problem since. It was the combination of harder cup and lack of proper seating. I did call the CCI tech back and apologized for being an idiot.”
Another Forum member witnessed a problem cause by misuse of a priming tool: “I did … see a failure to fire on a Rem 9 1/2 primer only a week ago. That was in the new Rem muzzleloader that uses a primed case to ignite the pellets. After watching the muzzleloader’s owner seat his primers, I believe that it was operator error not the primer. He was seating the primer and then squeezing the priming tool so hard that his hands hurt after a few. We got that corrected.”
Share the post "Having Primer Problems? Check Your Primer Seating Tool"
Tactical competitor Zak Smith stores his elevation and wind drift data on a handy laminated data card. To make one, first generate a come-up table, using one of the free online ballistics programs such as JBM Ballistics. You can also put the info in an Excel spreadsheet or MS Word table and print it out.
Above is a sample of a data card. For each distance, the card includes drop in inches, drop in MOA, drop in Mils. It also shows drift for a 10-mph cross wind, expressed in inches, MOA, and mils. Zak explained that “to save space… I printed data every 50 yards. For an actual data-card, I recommend printing data every 20 or 25 yards.” But Zak also advised that you’ll want to customize the card format to keep things simple: “The sample card has multiple sets of data to be more universal. But if you make your own data card, you can reduce the chance of a mistake by keeping it simple.”
Once you have the card you can fold it in half and then have it laminated at a local office store or Kinko’s. Keep this in your pocket, tape it to your stock, or tie the laminated card to your rifle. If you regularly shoot at both low and high elevations, you may want to create multiple cards (since your ballistics change with altitude). To learn more about ballistic tables and data cards, check out the excellent “Practical Long-Range Rifle Shooting–Part 1″ article on Zak’s website.
Scope-Cover Mounted Ballistics Table
Another option is to place your ballistics card on the back of the front flip-up scope cover. This set-up is used by Forum member Greg C. (aka “Rem40X”). With your ‘come-up’ table on the flip-up cover you can check your windage and elevation drops easily without having to move out of shooting position.
Greg tells us: “Placing my trajectory table on the front scope cover has worked well for me for a couple of years and thought I’d share. It’s in plain view and not under my armpit.
And the table is far enough away that my aging eyes can read it easily. To apply, just use clear tape on the front objective cover.”
A while back, Cal Zant at PrecisionRifleBlog.com did a big muzzle brake comparison test. Along with measuring recoil reduction, Cal’s team recorded sound levels in PRB’s exhaustive muzzle brake field tests. In the PRB archives you’ll find comprehensive muzzle brake sound test results, with hard data on 20 different muzzle brakes.
Sound can be a tricky subject, but Cal Zant, the editor of PrecisionRifleBlog.com, presents everything an informed shooter should know about muzzle brake noise in a straightforward and practical way. Most sound tests are measured from the side of the muzzle, in accordance with mil-spec standards, and Cal did that. But he also measured the sound level of each brake from behind the rifle, closer to the shooter’s position. This provides a more accurate indicator of the actual sound levels gun owners encounter while shooting.
Muzzle brakes ARE really loud — that’s something most active shooters have observed. But this study finally gives us some hard data and makes objective comparisons. The difference between brakes was quite significant. Some brakes were ear-splitting — more than twice as loud as other brakes tested.
As a bonus, Cal also provides data on how the Ultra series suppressors from Thunder Beast Arms Corp (TBAC) compare in terms of sound level behind the rifle.
Here are some really smart tips for hand-loaders compiled by Sierra Bullets. These suggestions were submitted by Sierra’s Facebook fans — and some are very valuable indeed. Some of these tips will help you load more accurate ammo. Other selections will help you stay SAFE — which should always be your #1 priority. For example, we concur with the advice to “Check and Double Check. Everything. Every Time”. Also definitely keep “One powder on the bench at a time” — that could be a life-saver. You may want to print these “words of wisdom” and place them on a wall in your loading room.
Reloading Safety Tips — Sound Advice
ALWAYS START LOW: “Just because a load manual says X grains of X powder with X bullet is max, your rifle could reach max pressure a grain or two before what the book says. Start low and work up.” — Walter Coats
BE SAFE and CAREFUL: “Check and double check. Everything. Every time. Only one type of powder on the bench at a time.” — Glen Lundgren
DON’T RUSH: “Be patient, don’t be in a hurry, have fun and find your rhythm. Just tell your family you’re putting yourself in ‘time-out’. They will understand.” — Erik Dyal
POWDER RULE #1: “One powder on the bench at one time, it might save your life.” — James A. Kimery
STAY FOCUSED: “Relaxed but concentrated attention. Have fun enjoying a great hobby and pastime but stay focused.” — Jim Caldwell
POLICE LOADING AREA: “Keep your reloading bench area clean and put items away ASAP.” — Eric J. Ford
BE PATIENT: “Focus, Focus, Focus — be patient — it AIN’T a race.” — William Stanley
RECORD YOUR LOADS: “Write down on a small card what you’re loading – bullet weight, powder weight, type of powder, and primer. And put it in the powder hopper. I am unloading .45 FMJ because I forgot what type powder was in the hopper.” — Michael Conniff
HAVE a PROCEDURE for INTERRUPTIONS: “If, for any reason, you have to leave the bench while in the process of dropping powder charges, turn the next case to be charged upside down in the loading block so you know where you left off.” — Bill Tinsley
LABEL EVERYTHING: “OCD is a good habit to have with your loading bench. CLEARLY label everything!” — Andy Pynckel
HAVE a GOAL: “Never start reloading or developing a load without a specific goal in mind. Second keep meticulous records.” — Peter Eick
RESEARCH THE JOB: “Read all you can about it before you start!” — Keith Shively
KEEP TRACK of the Brass: “I put all my primed brass upside down (primer up) and as I charge the casing, I (of course) flip it primer down.” — Mark Ewing
Click to Watch Hodgdon Pistol Reloading Video:
Share the post "Smart Tips for Reloaders from Sierra Bullets"
Will you be traveling (with firearms) to other states this year? Are you concerned about the laws that might apply when you are transporting guns across state lines? Or are you puzzled about the requirements for obtaining a carry permit in your own state? If you have any of these questions, you should definitely get expert guidance on State statutes and regulations controlling firearms. To do that, you can purchase Attorney Scott Kappas’s Traveler’s Guide to the Firearms Laws of the 50 States (2025) for just $16.95 from the publisher or $19.95 on Amazon. You can also get an eBook version for $15.95 (or $23.90 for eBook/Print combo). The latest 2025 edition includes 100+ updates since last year.
This very popular resource has sold over 2,000,000 copies since it was first released in 1996. The 2025 Edition just started shipping on 2/10/2025 — so this book is up to date. The print book is just $16.95 with FREE Shipping, or $20.95 with first-class shipping for quicker delivery.
Free State Law Summaries Online
If you don’t want to spend the money on the book, there is a FREE alternative. There’s a very helpful set of State Law Summaries on the web, presented by PewPewTactical.com. Despite the silly name, the PewPewTactical website has an abundance of information that is particularly beneficial for pistol shooters and CCW holders.
One of the best features of PewPewTactical.com is the Gun Laws by State online reference guide. We looked through four of these State Law Summaries and were impressed by the depth of the coverage. But we caution — if you have specific legal questions, particularly with recently-enacted statutes, you should consult a licensed attorney for your state (or the state to which you will travel). In addition, many of the State Law Summaries have not been updated for 3-5 YEARS! But they are still a good place to start. Below are links to state law articles from PewPewTactical.com. To access any State summary, simply click the State name below:
Above is a sectioned barrel showing an 80gr Sierra that was fired in a .223 bolt action with a cleaning rod in the bore. Both the bullet and the rod are still in the bore.
A Negligent Shooter Gets Lucky
“Here we have a story so filled with negligent acts that I can only marvel that the shooter survived the experience. The photo and narrative were provided by the gunsmith who took in the repair job, my comments are in italics. It’s worth reading, we can’t get enough safety warnings in our hobby.” — GS Arizona, Rifleman’s Journal
Description of Incident (with Commentary)
The shooter had a stuck case in his .223 chamber. The stuck case was actually a loaded round that didn’t fire. It wouldn’t extract because it was a .222 case that got mixed in with his .223 brass. [He had loaded the wrong brass.] I saw the loaded round with an 80gr bullet in it and a light primer strike. Negligent Act #1: Wrong brass was mixed in with the brass being reloaded.
The shooter removed the stuck case with a 3-piece aluminum rod. Negligent Act #2: Hammering out a loaded round with a cleaning rod. People have been killed doing this as the round can fire and drive the cleaning rod right into you. I remember one such incident about 5 years ago, the shooter was pounding out a stuck round, the cleaning rod went right through him, he didn’t survive.
The shooter didn’t notice only two segments of the cleaning rod came out when he removed it. Negligent Act #3: If you put anything at all down the barrel of a rifle you’d better make darn sure you got it all out before doing anything else!
He then chambered another round and fired it. Negligent act #4: If you’ve had a barrel obstruction of any kind, and if you’ve put something in the barrel, look through the barrel before proceeding! Within the past two years I know of an incident in which a benchrest shooter was killed in exactly this manner. The pressure built up and the rifle bolt came out of the receiver and into his chest.
The shooter is ‘OK’, but did not escape unscathed. He said there was a huge explosion and after regaining his senses found he was bleeding heavily from his forehead. The blood was thick enough that it ran in his eyes and he couldn’t see. In his words “I thought I was going to die”.
He has what looks like a pretty deep cut about an inch long on the side of his head, right in line with his right eye starting where the eye socket turns out to the side of the skull. And no telling what he’s got in the way of brass particles embedded in his forehead.
He was shooting on private property, and was alone when this happened. Negligent Act #5: Don’t shoot alone! Accidents happen, this is just one more example. If we could predict accidents, we wouldn’t have them. Always shoot with at least one other person.
He managed to get the bleeding stopped, or at least under control, packed his car and drove himself home without seeking immediate medical attention. Negligent Act #6: This one could have cost him his life after being lucky enough to survive the incident. There’s no way to know what’s happened just after an incident like this. He should have been at a hospital getting checked for shrapnel in the head.
The rod and slug could not be driven out. Since the barrel had a high round count there was no point in trying to salvage it. Note that the aluminum rod is expanded to a tight fit in the bore for the first couple inches. The base of the bullet is a little over 2″ from the mouth of the chamber.
What we’ve seen here is negligence and an absolute indifference to the established rules of safe reloading and gun handling, from start to finish, capped off with the shooter’s foolish avoidance of medical treatment. This shooter is lucky to be alive, but he’s surely used up all his luck. Don’t assume you’ll be so fortunate.
This article originally appeared in the Rifleman’s Journal website, which is no longer available. The Rifleman’s Journal site was created by German Salazar, who, sadly, has passed. He was a great shooter who helped this website in many ways. RIP German.
Share the post "Beware Barrel Bore Obstructions — They Can Cause Accidents"
Editor: Many new barrels will deliver higher velocities with the same load after 100-150 rounds through the bore. The exact reasons for this speed-up are not 100% certain, and velocity increases (if any) will vary from one barrel to the next. But this “speeding up” phenomenon is common, so be prepared if this happens with your next barrel. If you do experience a significant velocity increase you should probably re-tune your load AFTER the velocity stabilizes at the higher level.
From the Sierra Bullets Newsletter Article by Mark Walker, Sierra New Product Development Director
In a previous post, I discussed a couple of methods to tune a load to your barrel to help achieve the best accuracy possible. People most often work on load tuning if they get a new rifle or have a different barrel installed. In both instances, the barrel is new and has not been fired very much. According to most competitive shooters, this is the most accurate your barrel will ever be, so getting it tuned and shooting accurately is a priority.
The Speed Up Phenomenon After 100-150 Rounds
Even though after you work up a load and your new barrel is shooting great, a lot of shooters notice that at around 100 to 150 rounds their rifle may stop shooting as accurately. I had this happen to a rifle and I was confused as to why something that worked so well to begin with would all of a sudden quit shooting. I decided to break out the chronograph to do another load work up to see what was going on. To my surprise, the velocity had increased around 80 fps over the original velocity! After performing another ladder test and adjusting the seating depth, the rifle was once again shooting well.
There are several thoughts on why this may happen, however, you can rest assured that it does happen. One thought is that as the barrel breaks in, the tooling marks in the throat of the chamber smooth out and allow less resistance to the bullet as it exits the bore thereby increasing speed. Another idea is that the throat area starts to get a little rough which in turn causes more resistance which increases pressure and therefore more velocity. I’m sure there are some out there who have a better understanding as to why this happens, but it can definitely affect the accuracy of your rifle. So be aware and never be afraid to rework a load to keep your rifle in tune.
Experts Confirm That Barrel Speed-Up Is Common Two respected shooters have observed an increase in velocity with new barrels, typically after 100 rounds. Gunsmith and Hall-of-Fame benchrest shooter Thomas “Speedy” Gonzalez has documented barrel speed-up with testing. Moreover, Speedy’s bore-scope barrel inspections revealed a smoothing of the barrel lands. Jim See, a top PRS competitor, has encountered barrel speed-up many times. Accordingly, he re-tunes his load at 150 rounds.
“Alex Lipworth and I documented this phenomenon about four years ago and I have told all my customers about this. My son Mikee would shoot 100 rounds through all new barrels we planned on shooting before we would begin to do load development. We had a shooting snail that caught all the bullets set up in front of an indoor bench. We called it a wear-in process because upon careful examination of the bore when the ‘Speed Up’ takes place the cut-rifled bore resembles that more of a button-rifled barrels with the lands taking on more the softer look of a buttoned bore.” — Speedy Gonzalez
“Seen it [barrel velocity increase] too many times to count. All my match barrels get a ‘generic round’ loaded for them, which has worked well in barrels historically. After I hit 150 rounds I fine-tune the load and never look back, until the tube starts to slow down at it’s life end.” — Jim See
Share the post "Why Barrels May Deliver Higher Velocity after 100-150 Rounds"
Do you know which one of your eyes is dominant? It’s easy to determine eye dominance with a simple exercise. Pick an object about 6-10 feet away (a light switch or door knob works well). Make an “OK” sign with your right hand (see photo) and hold that about 18″ from your face. Now, with both eyes open, look through the circle formed by your thumb and index finger. Center the circle on the object, so you can see the object in the middle.
Scope-Cover Mounted Ballistics Table
Two respected shooters have observed an increase in velocity with new barrels, typically after 100 rounds. Gunsmith and Hall-of-Fame benchrest shooter Thomas “Speedy” Gonzalez has documented barrel speed-up with testing. Moreover, Speedy’s bore-scope barrel inspections revealed a smoothing of the barrel lands. Jim See, a top PRS competitor, has encountered barrel speed-up many times. Accordingly, he re-tunes his load at 150 rounds.
