We will be interviewing Bryan Litz of Applied Ballistics tomorrow at SHOT Show in Las Vegas. As a sneak preview of some of the topics we’ll cover, here are some highlights of some important, original research conducted by Bryan and his Applied Ballistics team. Bryan wanted to know how much velocity was altered by twist rate. The “real world” test results may surprise you….
The Applied Ballistics team tested six (6) same-length/same-contour Bartlein barrels to observe how twist rate might affect muzzle velocity. This unique, multi-barrel test is featured in the book Modern Advancements in Long Range Shooting. That book includes many other fascinating field tests, including a comprehensive chronograph comparison.
Barrel Twist Rate vs. Velocity — What Tests Reveal by Bryan Litz
When considering barrel twist rates, it’s a common belief that faster twist rates will reduce muzzle velocity. The thinking is that the faster twist rate will resist forward motion of the bullet and slow it down. There are anecdotal accounts of this, such as when someone replaces a barrel of one brand/twist with a different brand and twist and observes a different muzzle velocity. But how do you know the twist rate is what affected muzzle velocity and not the barrel finish, or bore/groove dimensions? Did you use the same chronograph to measure velocity from both barrels? Do you really trust your chronograph?
Savage Test Rifle with Six Bartlein Barrels
Most shooters don’t have access to the equipment required to fully explore questions like this. These are exactly the kinds of things we examine in the book Modern Advancements in Long Range Shooting. In that book, we present experiments conducted in the Applied Ballistics lab. Some of those experiments took on a “Myth Buster” tone as we sought to confirm (or deny) popular pre-conceptions. For example, here’s how we approached the question of barrel twist and muzzle velocity.
Six .308 Win Barrels from Bartlein — All Shot from the Same Rifle
We acquired six (6) barrels from the same manufacturer (Bartlein), all the same length and contour, and all chambered with the same reamer (SAAMI spec .308 Winchester). All these barrels were fitted to the same Savage Precision Target action, and fired from the same stock, and bench set-up. Common ammo was fired from all six barrels having different twist rates and rifling configurations. In this way, we’re truly able to compare what effect the actual twist rate has on muzzle velocity with a reasonable degree of confidence.
Prior to live fire testing, we explored the theoretical basis of the project, doing the physics. In this case, an energy balance is presented which predicts how much velocity you should expect to lose for a bullet that’s got a little more rotational energy from the faster twist. In the case of the .30 caliber 175 grain bullets, the math predicts a loss of 1.25 fps per inch-unit of barrel twist (e.g. a 1:8″ twist is predicted to be 1.25 fps slower than a 1:9″ twist).
Above, data shows relationship between Twist Rate and Muzzle Velocity (MV) for various barrel twist rates and rifling types. From fast to slow, the three 1:10″ twist barrels are: 5R (canted land), 5 Groove, 5 Groove left-hand twist.
We proceeded with the testing in all 6 barrels from 1:8” to 1:12”. After all the smoke cleared, we found that muzzle velocity correlates to twist rate at the rate of approximately 1.33 fps per inch of twist. In other words, your velocity is reduced by about 5 fps if you go from a 1:12” twist to a 1:8” twist. [Editor: That’s a surprising number — much less than most folks would predict.] In this case the math prediction was pretty close, and we have to remember that there’s always uncertainty in the live fire results. Uncertainty is always considered in terms of what conclusions the results can actually support with confidence.
This is just a brief synopsis of a single test case. The coverage of twist rates in Modern Advancements in Long-Range Shooting is more detailed, with multiple live fire tests. Results are extrapolated for other calibers and bullet weights. Needless to say, the question of “how twist rate affects muzzle velocity” is fully answered.
Other chapters in the book’s twist rate section include: · Stability and Drag – Supersonic
· Stability and Drag – Transonic
· Spin Rate Decay
· Effect of Twist rate on Precision
Other sections of the book include: Modern Rifles, Scopes, and Bullets as well as Advancements in Predictive Modeling. This book is sold through the Applied Ballistics online store. Modern Advancements in Long Range Shooting is also available in eBook format in the Amazon Kindle store.
Wouldn’t it be interesting if a major manufacturer of tactical rifles turned its attention to the long-range competition game, specifically F-Class? Well, that is happening. Last year Ashbury Precision Ordnance (APO) rolled out a patriotic Stars and Stripes F-TR rifle, and this year APO has created an impressive new F-Open rifle. APO’s new F-Open rifle is based on the SABER Modular Rifle Chassis System (MRCS), as fitted a new front end. APO’s F-Open rifle features a long, aluminum fore-end with a 3 inch-wide bag-rider section. This provides excellent stability on the bags and offers a “long wheelbase” for improved tracking. At the rear, APO provides a metal bag-rider that runs fore-and-aft under the cheekpiece.
CNC-machined from billet aluminum alloy, the fore-end on APO’s F-Open rig features a three-inch wide Catamaran design (with twin “rails” on the underside). This long fore-end can be custom weight-balanced to meet the F-Open class 10kg weight limit. APO’s new F-Open rifle also boasts a rear Bag Rider that replaces the butt hook found on APO’s tactical rigs. The rear buttstock section features adjustable length of pull (via spacer), adjustable cheek piece, and adjustable drop for the Limbsaver®-equipped buttplate.
The SABER F-Open 6.5-284 Competition Rifle is built around APO’s octagonal SABER® LX receiver, which can be supplied with a detachable magazine or single-shot target block. APO’s bolt action receivers take advantage of a unique interlocking design in the Center Chassis Section that provides additional holding strength on both right and left hand models. The trigger is a two-stage, adjustable Tubb T7T trigger set to 1.0-1.5 pounds pull. The barrel is a button-rifled, stainless 4R Heavy Palma contour from MullerWorks. Customers can elect barrel lengths up to 30 inches.
Rifle Available as a Complete Package
The complete 6.5-284 F-Open Competition Rifle package includes a Leupold VX-6 7-42x56mm rifle scope. The base weight of the F-Open MRCS chassis (by itself) is 6.25 pounds and it can be weight-adjusted as desired by the shooter. The SABER F-Open Competition Series MRCS will be available in popular Cerakote finishes as well as hard-anodized colors. “We wanted to build a solid F-Open rifle that a shooter could take right into competition and be competitive”, says Matthew Peterson, Ashbury’s Product Development Coordinator.
Ashbury will showcase its new SABER F-Open competition rifle (chambered in 6.5-284 Winchester) at SHOT Show Booth #31407. To learn more about Ashbury Precision Ordnance’s line of rifle chassis systems, precision rifles, and long range shooting accessories, visit the Ashbury Web Portal.
Are you a 6 PPC shooter who relies on Vihtavuori N133? Or maybe you’re a .45 ACP Bullseye shooter who uses N310 or N320. Or perhaps you favor N150 in your 6mmBR or .308 Winchester. If you are a Vihtavuori powder user (or are considering trying these fine Finnish powders), then check out Vihtavuori’s new FREE mobile App.
The new Vihtavuori Reload App lets you keep track of your favorite reloading recipes, and manage load development. You can log load recipes for as many firearms and cartridge types as you want. The App holds all relevant data — cartridge class, bullet, loads specs. The Vihtavuori Reload App also provides instant access to the latest Vihtavuori Reloading Data as well as other Vihtavuori information. If you want hard copy of your load recipes, just email the recipe(s) to your personal e-mail account and then you can print out the info with a networked printer.
For over 90 years, Vihtavuori has been known for producing high-quality propellants with reliable ballistic performance, long shelf-Life, and a wide selection of burn rates. Vihtavuori powders are manufactured to very high standards, and many world records have been set with Vihtavuori propellants. For more information, visit www.Vihtavuori.com.
As a visual treat for our Daily Bulletin readers, we went back to our Gun of the Week archives to showcase a very special rifle. This humdinger could be the prettiest prone rifle we’ve ever seen. Commissioned for Forum member Corbin S., this is one handsome rifle, built with all-premium components and a stunning Curly Maple thumbhole stock with adjustable cheekpiece. The rifle is chambered in .243 Winchester. It features a custom stainless RBRP action Nesika R action, with keycuts in the bottom instead of recoil lug. A Grünig & Elmiger trigger has been specially modified (milled and pinned) to work with the Nesika action. The barrel is a 30″ Broughton 5R Palma-contour tube, and there is another 30″ Broughton 6BR barrel that Corbin uses at shorter ranges. The trigger guard, fore-arm rail, cheek adjuster, and 4-way adjustable butt assembly are all custom metal, designed by Dan Gleason. The stock is cut from exhibition-grade fiddleback maple (from Cecil Fredi Gunstocks in Las Vegas) with a Gaboon Ebony tip wood and butt-plate spacer.
Very Accurate with Fast-Flyin’ Berger 105s
Corbin tells us the gun will put five shots into the size of a quarter at 300 yards “when he does his part.” Corbin shoots pointed Berger 105gr VLDs and 45.5 grains of H4831SC. That load runs 3180 fps. He can push it faster, but “that’s where the node was and where it shoots best”, according to Corbin.
Forum member Jim Hardy has seen (and shot against) this beautiful rifle. He reports:
“A casual observer might think that the trigger guard, cheek plate and butt plate hardware are Anschutz — as the stock takes on the Anschutz prone pattern. However, this is ALL custom metal. The G&E trigger breaks like a glass rod and will makes my BR triggers feel inferior at best. I had the pleasure of holding, shouldering, and lusting over this gun at Camp Perry last year, and it is even more impressive in person. The killer is that there is yet ANOTHER one in a beautiful, dark figured walnut owned by Corbin’s shooting partner. BTW, both guns will hammer at 1000 yards prone.”
AR-platform rifles can be maintenance-intensive beasts. But some AR owners make the situation worse by not regularly cleaning important small parts, or by using too much oily/greasy lubricants in the wrong places. A properly maintained and lubricated AR15 can shoot hundreds of rounds (between cleanings) without a problem. If you learn where (and where not) to apply lubricant, you’ll find that your AR will run more reliably and the task of cleaning the bolt and bolt carrier will be less of a burden.
Here is a good video that explains AR-15 Cleaning and Maintenance. In this 30-minute NSSF video, Gunsite Academy instructor and gunsmith Cory Trapp discusses the proper way to clean and maintain the AR-15 carbine. Very knowledgeable, Trapp provides rock-solid advice for AR owners. Along with cleaning producedures, this video explains how to inspect key components and how to function-test your AR before each shooting session.
Savage Arms, now part of Vista Outdoor, will be offering many new guns for 2016. The big news is the A22, a .22 WMR version of Savage’s popular A17 semi-auto rifle (chambered in 17 HMR). Also debuting for 2016 are more variants of A17 and B.MAG rifle series, plus as all-new Model 42 Takedown shotgun-and-rifle combination gun. Along with the all-new models, Savage will add new chamberings to existing rifle types. For example, Savage AXIS and AXIS II rifles will soon be available chambered for the popular 6.5 Creedmoor.
Savage New Product Highlights for 2016
Savage A22 Magnum in .22 WMR (NEW)
The new A22 Magnum is chambered for .22 WMR (Winchester Magnum Rimfire) and features the same, innovative delayed-blowback, semi-automatic action as the original A17 (which was chambered in 17 HMR). We expect the new A22 to be popular with varminters who prefer to shoot a bigger, heavier bullet, or who find .22-caliber barrels easier to clean.
Savage Model 42 Takedown (NEW) — .410ga and .22 LR
The Model 42 Takedown is a break-open combo gun that fires rimfire rounds from the top barrel and .410 bore shotgun shells from the bottom. It breaks down with the push of one button and includes an Uncle Mike’s Go Bag for transport.
Savage A17 — Wood Stock, Bull Barrel
New-for-2016 A17 target models feature heavy barrels for increased accuracy and gray wood laminate stocks improved feel and handling. We feel the new laminated stock really improves tha A17 as a general purpose varmint gun.
Savage B.MAG — New Stocks, Heavier Barrel Option
Savage’s B.MAG was built around the 3000 fps 17 Winchester Super Magnum rimfire cartridge. For 2016, three new models have been added to the B.MAG lineup: Target Beavertail, Heavy Barrel, and Sporter.
6.5 Creedmoor Chambered Rifles
Savage Arms has added nine new rifles chambered for the popular 6.5 Creedmoor cartridge. They include the new model 16 Lightweight Hunter, AXIS, AXIS LH, AXIS XP, AXIS XP Camo, AXIS XP Stainless, AXIS II XP, AXIS II XP Stainless and AXIS II XP Hardwood.
See New Savage Guns at SHOT Show
Savage’s new-for-2016 products can be viewed during SHOT Show at the Vista Outdoor booth (#14551). Product photos and specs will appear on SavageArms.com after the show.
Hail the Rail. If you are looking to put multiple shots through one hole, the Unlimited Class benchrest gun, aka “Rail Gun”, is the firearm of choice. These heavy Unlimited rigs are the most accurate benchtop shooting machines ever created. Campaigned by ace competitors in the 100/200-yard benchrest game, rail guns are capable of delivering the ultimate in rifle accuracy — multiple 5-shot groups in the ones and zeros.
Watch Video to Learn More about Rail Guns and See Them in Action:
In this video, YouTuber “Taofledermaus” takes a look at high-tech rail guns on display at the Visalia (CA) shooting range. He says: “The Unlimited Class rail guns are indeed the epitome of precision shooting. [These rifles] resemble something out of a ballistics test laboratory. Each [rail gun] weighs about fifty pounds…”
One-Hole Accuracy with Rail Gun
What kind of accuracy can a top-of-the-line rail gun deliver? Check out this target shot by our friend Lou Murdica in January 2015 in Phoenix. Sometimes superlatives really aren’t necessary. Just look at that target. Yes that is FIVE shots (although it truly appears like one hole). And it is centered! This remarkable group measured at 0.039″. Lou drilled this group with one of his 6 PPC railguns. Rounds were loaded with Accurate LT-32 powder and Berger 65gr BT bullets. The target was submitted to the NBRSA as a potential new 100-yard Benchrest record in the Unlimited (Railgun) Class.
This is a file photo with Lou Murdica with a different rail gun (not the one that shot above target).
Story/video tip by Boyd Allen. We welcome reader submissions.
Here’s a “spy photo” of the new scope. Price and release date are yet to be determined.
If you’ve been planning to purchase a premium, high-magnification, variable-power competition scope this year… you may want to hold off for a few weeks. We just learned that Schmidt & Bender will be introducing an all-new, “super-zoom” optic for 2016. Schmidt & Bender’s impressive new 5-45x56mm PM II High Power, offers a remarkable 9X zoom ratio. That makes it suitable for a wide variety of shooting disciplines. A tactical competitor can dial back to 5-power for a wide field of view on close-in targets. Or, for 1000-yard shooting, crank the scope all the way up to 45-power. S&B says the scope is intended for “tactical ultra-long-range shooting”. With its ultra-bright, ultra-sharp German glass, this new scope could also become popular with F-Class competitors — if it is priced reasonably. We called Schmidt & Bender USA, but we were informed that no further product details or pricing information could be released prior to SHOT Show.
In addition to the new 5-45X comp scope, Schmidt & Bender plans to introduce six other new scope models in 2016. There will be two Polar T96 models, a 3-12X and a 4-16X. The current 2.5-10X Polar T96 boasts an industry-leading 96% light transmission. S&B claims this is the “brightest low-light hunting scope in the world”. For 2016, S&B will also introduce two PM II models with digital reticle display features, the 3-27X and 5-25X “Digital BT” scopes. Finally, two new PM II “Ultra-Bright” scopes will be added to the lineup. We believe these will be a 3-12X and a 4-16X.
Need a gun safe? Well now there’s a modular vault option from “Big Red”, Hornady Manufacturing. Hornady has acquired SnapSafe, manufacturer of modular safes. Delivered in sections and assembled on site, SnapSafe vaults combine steel-walled security with ease of mobility and installation. The heaviest segment of a SnapSafe is typically under 100 pounds so one adult male can lift and move the safe sections up stairs (or anywhere else). SnapSafe vaults feature 9-gauge steel walls, 8 chrome steel 3/4″ locking bolts, and a one hour (2,300°) fire rating.
SnapSafe modular gun vaults are delivered on a pallet right to your door and can be assembled in minutes. The assembly process is illustrated in the video above. Basically the safe bolts together — it’s a bit like assembling an IKEA cabinet. In addition to conventional safes, SnapSafe also manufactures lock boxes and auxiliary safes that can be stored in trunks, under beds, or in walls. SnapSafe products will be on display at booth #2119 at Shot Show, January 19-22. For more information on SnapSafe products, visit www.Snapsafe.com.
Our friend Erik Cortina told us that Jim Borden of Borden Accuracy has developed a new “wide-body” action, the Borden BRMXD. Erik is building a rifle around this action to shoot at the 2016 Berger SW Nationals. The new BRMXD is Borden’s first venture into action bodies larger than 1.350″ in diameter. The round BRMXD action measures a stout 1.470″ in diameter and comes standard with bottom recoil lug. If the customer prefers, Border can deliver the action with a conventional recoil lug on the front. We like the looks of Borden’s new BRMXD, and we bet this new stainless action will be a smooth runner.
Borden BRM-XD Action Specifications:
• Action: BRM-XD
• Length: 8-1/8″
• Outside Diameter: 1.470″
• Port Length: Single Port: 2.750″
— Dual Port w/ Mini Port for BR / PPC: 2.750″ Loading & 1.8″ Eject Port
— Dual Port w/ x47 Family Port: 2.750″ Loading & 1.9″ Eject Port
— Dual Port w/ .284 Family Port: 2.750″ Loading & 2.4″ Eject Port
• Weight: 42.6 oz for Single Port
• Price: $1325.00 with bottom lug for a single port – $1400.00 for a dual port + shipping
• Price: $1250.00 for no lug (Glue-In Only)
Borden Accuracy will also offer a 0.215″ spacer for shooters who wish to use their current PANDA barrels with a new BRMXD action. This hardened steel spacer will cost $50.00 (introductory price).
This is just a brief synopsis of a single test case. The coverage of twist rates in Modern Advancements in Long-Range Shooting is more detailed, with multiple live fire tests. Results are extrapolated for other calibers and bullet weights. Needless to say, the question of “how twist rate affects muzzle velocity” is fully answered.
Savage A22 Magnum in .22 WMR (NEW)
