June 20th, 2017

Tactical Twins: Micarta-Stocked PRS Rigs for SFC Brandon Green

SFC Brandon Green PRS Rifle Micarta Foundation Stocks

What does a two-time High Power National Champion choose for PRS comps? A set of twins. Twin rifles that is. SFC Brandon Green of the USAMU is one of America’s best marksmen. He’s excelled in Service Rifle and High Power disciplines, and now he’s getting very serious about the Precision Rifle Series (PRS). Brandon recently took delivery of “Twins” — two impressive rifles optimized for PRS competition. Green told us: “The Twins are ready for business! The silver one is a 6XC and the black one is a 6.5×47 Lapua”. Both rifles feature Impact Precision actions (with AICS-type mags), 24″ Proof stainless barrels, and Fat Bastard muzzle brakes. Rifle work was done by Stuteville Precision (Wade Stuteville) and Exodus Rifles (Joe Walls).

SFC Brandon Green PRS Rifle Micarta Foundation Stocks
In the 6XC, Brandon runs Berger 105gr VLDs in Norma 6XC brass. For the 6.5×47 Lapua he shoots 140gr Berger Hybrids or 143gr Hornady ELD-Xs in Lapua brass. Both rifles have stainless steel Proof barrels, but the 6.5x47L has a matte black Cerakote finish.

Brandon loves his new Twins. He said he likes the “feel” of the guns with the Foundation stocks: “These rifles weigh around 17 pounds with optics. They feel very solid under recoil — without the ‘tuning fork’ vibration you can get with a metal-chassis gun. They feel like a good wood-stocked gun, but the material is stronger and more rigid than wood. I’ve heard that guys are having success with these Foundation stocks with the actions installed without pillars or conventional bedding.” Currently Brandon is running both guns without action-screw pillars. He did have one skim-bedded, but he doesn’t think that was really needed. “Both rifles hammer now”, Brandon tells us.

Green Runs Vortex Razor HD Gen II 4.5-27x56mm FFP scopes on both rifles:
SFC Brandon Green PRS Rifle Micarta Foundation Stocks

High-Tech Micarta Stock Material
At first glance, those stocks may look like wood, but they are actually a special “Micarta” material that is strong, durable, and stable. Micarta, often used for knife handles, is a “a brand name for composites of fiberglass, carbon fiber, or other fabric in a thermosetting plastic.” The stock-maker, Foundation Stocks, says Micarta offers some distinct advantages over laminated wood or conventional fiberglass: “The solid block of material gives us a dense, homogenous material that is absent of any voids or air pockets commonly found in composite stocks. The high compression strength of the material allows us to build an action/DBM specific stock that requires no bedding or pillars. The material is very durable and stable in extreme environments. We use advanced CAD software to design and model our stocks, working in conjunction with action manufacturers and rifle builders to provide exact fitment.”

Here is a close-up of a Foundation Stock showing the distinctive Micarta texture:
SFC Brandon Green PRS Rifle Micarta Foundation Stocks

Tactical Competition vs. NRA High Power Competition
Brandon says PRS competition is tough: “PRS can be pretty humbling, but it’s been a lot of fun and a great challenge. For a shooter (like me) with a Service Rifle/High Power background, the variations in stages combined with the time limits can be very challenging. And the unusual shooting positions put a new spin on things. PRS is definitely a different ball game, but I really enjoy it. After the National Championships this summer I hope to shoot three or four PRS matches in September and October.”

SFC Brandon Green 2015 High Power National Championship
SFC Brandon Green honored as the 2015 High Power National Champion.

Life before the Twins… Here is Brandon, with his previous PRS rig, at the MasterPiece Arms Precision Rifle Shootout, a PRS event at the CORE Shooting Solutions Range in Florida:

SFC Brandon Green PRS Rifle Micarta Foundation Stocks

Permalink Gear Review, Gunsmithing, Tactical 12 Comments »
June 20th, 2017

Tangent vs. Secant vs. Hybrid — Bullet Ogive Geometry Explained

Secant and Tangent Ogive Bryan LitzWe know many of our readers aren’t 100% clear on the difference between a secant ogive bullet and a tangent ogive bullet. Add the “blended” or “hybrid” ogive into the design equation and you add to the confusion. In this article, Berger Ballistician Bryan Litz, explains the characteristics of the three popular ogive types: tangent, secant, and hybrid.

In discussions of ballistics, you’ll see references to “tangent” and “secant” bullet shapes. For many readers, these terms can be confusing. To add to the confusion, bullet makers don’t always identify their projectiles as secant or tangent designs. This article provides a basic explanation of tangent and secant designs, to help you understand the characteristics of both bullet shapes.

Tangent vs. Secant vs. Hybrid
Most match bullets produced today use a tangent ogive profile, but the modern VLD-style bullets employ a secant profile. To further complicate matters, the latest generation of “Hybrid” projectiles from Berger Bullets feature a blended secant + tangent profile to combine the best qualities of both nose shapes. The secant section provides reduced drag, while the tangent section makes the bullet easier to tune, i.e. less sensitive to bullet seating depth position.

Berger Bullets ballistician Bryan Litz explains tangent and secant bullet ogive designs in a glossary section of his Applied Ballistics website, which we reprint below. Bryan then explains how tangent and secant profiles can be combined in a “hybrid” design.

How Bullet Ogive Curves are Defined
While the term “ogive” is often used to describe the particular point on the bullet where the curve reaches full bullet diameter, in fact the “ogive” properly refers to the entire curve of the bullet from the tip to the full-diameter straight section — the shank. Understanding then, that the ogive is a curve, how is that curve described?

LITZ: The ogive of a bullet is usually characterized by the length of its radius. This radius is often given in calibers instead of inches. For example, an 8 ogive 6mm bullet has an ogive that is a segment of a circular arc with a radius of 8*.243 = 1.952”. A .30-caliber bullet with an 8 ogive will be proportionally the same as the 8 ogive 6mm bullet, but the actual radius will be 2.464” for the .30 caliber bullet.

For a given nose length, if an ogive is perfectly tangent, it will have a very specific radius. Any radius longer than that will cause the ogive to be secant. Secant ogives can range from very mild (short radius) to very aggressive (long radius). The drag of a secant ogive is minimized when its radius is twice as long as a tangent ogive radius. In other words, if a tangent ogive has an 8 caliber radius, then the longest practical secant ogive radius is 16 calibers long for a given nose length.”

hybrid bullet

Ogive Metrics and Rt/R Ratio
LITZ: There is a number that’s used to quantify how secant an ogive is. The metric is known as the Rt/R ratio and it’s the ratio of the tangent ogive radius to the actual ogive radius for a given bullet. In the above example, the 16 caliber ogive would have an Rt/R ratio of 0.5. The number 0.5 is therefore the lowest practical value for the Rt/R ratio, and represents the minimum drag ogive for a given length. An ogive that’s perfectly tangent will have an Rt/R ratio of 1.0. Most ogives are in between an Rt/R of 1.0 and 0.5. The dimensioned drawings at the end of my Applied Ballistics book provide the bullets ogive radius in calibers, as well as the Rt/R ratio. In short, the Rt/R ratio is simply a measure of how secant an ogive is. 1.0 is not secant at all, 0.5 is as secant as it gets.

Berger Hybrid bullet, .308 30 CaliberHybrid Bullet Design — Best of Both Worlds?
Bryan Litz has developed a number of modern “Hybrid” design bullets for Berger. The objective of Bryan’s design work has been to achieve a very low drag design that is also “not finicky”. Normal (non-hybrid) secant designs, such as the Berger 105gr VLD, deliver very impressive BC values, but the bullets can be sensitive to seating depth. Montana’s Tom Mousel has set world records with the Berger 105gr VLD in his 6mm Dasher, but he tells us “seating depth is critical to the best accuracy”. Tom says a mere .003″ seating depth change “makes a difference”. In an effort to produce more forgiving high-BC bullets, Bryan Litz developed the hybrid tangent/secant bullet shape.

Bryan Litz Explains Hybrid Design and Optimal Hybrid Seating Depths

Story sourced by Edlongrange.
Permalink - Articles, Bullets, Brass, Ammo 1 Comment »
June 20th, 2017

Major Brand Factory Second Bullets Sale at MidwayUSA

Factory seconds blemished blem bullets 6mm 7mm .308 MidwayUSA Nosler Hornady Sierra

MidwayUSA is running a big sale on Factory Second and Blemished Bullets. These bullets normally perform just as well as regular bullets, but they may have water spots or other cosmetic defects. MidwayUSA has a very large selection of seconds/blem bullets on sale for both rifles and pistols. Here are some of the best deals we found among the quality varmint and match rifle bullets. All these selections are discounted 30%:

.224 Caliber (5.56mm) 50gr Polymer Tip Spitzer, $13.49/100 (30% Off)
.224 Caliber (5.56mm) 52gr HPBT Match, $13.29/100 (30% Off)
.224 Caliber (5.56mm) 53gr Polymer Tip BT Varmint, $13.29/100 (30% Off)
.224 Caliber (5.56mm) 77gr Nosler HPBT Match, $18.89/100 (30% Off)
.243 Caliber (6mm) 65gr Polymer Tip Spitzer Varmint, $16.09/100 (30% Off)
.264 Caliber (6.5mm) 123gr Polymer Tip BT Match, $20.29/100 (30% Off)
.264 Caliber (6.5mm) 140gr HPBT Match, $21.69/100 (30% Off)
.308 Caliber 155gr Polymer Tip Spitzer BR Match, $20.99/100 (30% Off)
.308 Caliber 168gr Polymer Tip Spitzer BT Match, $21.69/100 (30% Off)
.308 Caliber 195gr BTHP Match, $24.49/100 (30% Off)
.308 Caliber 208gr Polymer Tip Spitzer BT Match, $25.89/100 (30% Off)

Factory seconds blemished blem bullets 6mm 7mm .308 MidwayUSA Nosler Hornady Sierra

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