I had been itching to shoot a 6mm Dasher for years, with my interest being inspired by its stellar reputation for accuracy and something I had read involving a 2.6872-inch, 10-shot group shot from 1,000 yards by Jim Richards in 2014, at the Deep Creek Range near Missoula, Montana. That set a world’s record for the Light Gun class. So, I contacted Phil Cashin, owner of Masterpiece Arms (MPA) and maker of chassis rifles so accurate, they serve to set a benchmark for any precision cartridge tested.

The rifle Cashin ultimately delivered was a MPA Matrix Pro PMR Rifle designed to meet the Production Class requirements of the 2023 Precision Rifle Series, better known as PRS. This rifle was based on the company’s new Matrix Pro II chassis, holding a barreled action also used on MPA’s PMR Series rifles. It was fitted with a 26-inch, 1:7 twist MPA/Spencer barrel cut from 416RQ stainless steel and included a heavy match contour. MPA barrels are stress relieved and hand-lapped before undergoing video borescoping and inspection with a Sheffield air gage to guarantee specifications within .0001 inch. The chamber is indicated within less than .0001 inch to the rifle bore. The chamber was reamed specifically for Petersen’s Cartridge brass and an MPA DNS muzzle brake was added to the 5/8x24 threads. The Curtis Custom action includes a three-lug bolt that runs slickly, an integral recoil lug and 20 MOA Picatinny rail. The three-piece bolt includes spiral fluting, black nitride coating, a mechanical extractor, and a quick release firing pin assembly that allows quick, toolless cleaning.

The chassis is milled from 6061 aluminum and includes a V-bedding system with clearance for glass bedding the action and straight section of the barrel. The comb and buttplate are adjustable for fit via thumb wheels (length of pull - 12.75 to 14 inches) and a bag rider hook is included. Incorporated features included a night vision bridge, Picatinny rail, Arca Swiss Rail and RAT systems, built-in inclinometer bubble level, Matrix EVG grip and thumb ledge. The trigger was MPA’s Bix N Andy Tac Sport Pro Custom, which broke at slightly more than 1 pound. The 10-round Accurate Mag fed reliably. The rifle was delivered in a basic Plano case.

MPA guarantees 3/8-inch accuracy.

A Zero Compromise Optic ZC 840 8-40x 56mm was mounted in an Austrian-made Zero Compromise Block Mount one-piece base, which included a swing-out level. This is unequivocally as fine a precision long-range scope as money can buy, all parts are manufactured in Austria and assembled in Orofino, Idaho. It included pop-up locking turrets (mil in this case) and an MPCT 2X illuminated reticle. The Austrian glass is ultra-sharp and bright, even after twisting magnification all the way up to 40 power. The full rundown on this scope is featured in Wolfe Publishing’s Rifle No. 335 (July – August 2024) magazine. The Matrix Pro PMR Rifle weighed 16 pounds out of the box, and 20.86 pounds after mounting the scope. The rifle’s not-insubstantial heft, DNS muzzle brake and mild-mannered 6mm Dasher chambering made shooting extremely pleasant.

Jim Richard’s Light Gun Class world’s record was no accident, as the 6mm Dasher was designed for just such tasks. The 6mm Dasher now has an unprecedented list of 600- and 1,000-yard benchrest records to its name. It was purpose built to launch bullets with high-ballistic coefficients at 2,900-3,000 feet per second (fps) and provide less drop and recoil than cartridges like the 6.5 Creedmoor. This has made it the choice of many serious PRS shooters.

Dan Dowling and Al Ashton created the 6mm Dasher in 1999 by blowing the shoulders of the 6mm BR .100-inch forward, creating a 40-degree shoulder and .260-inch neck during fireforming. This resulted in a 10 percent increase in case capacity and 100 to 130 fps increases in velocity over the parent cartridge (with 105-grain bullets). The Dasher sits between the 6mm BR Norma and 6mm Creedmoor in powder capacity, with competitive barrel life normally spanning 2,500 to 3,000 rounds. Professional powder favorites include Alliant Reloder 15 and Hodgdon Varget.

The Dasher is technically a wildcat, as it is still without the Sporting Arms and Ammunition Manufacturers’ Institute (SAMMI) blueprints, but is a decidedly domesticated one. I say this because ready-made brass can be purchased from Norma, Alpha Munitions and Peterson Cartridge – the latter used for testing here. Peterson cases hold small rifle primer pockets with .060-inch flash holes requiring a slim decapping pin. Peterson based case dimensions on specifications found in Sierra, Berger and Lyman handloading manuals, including .0013-inch-thick neck walls that require no turning, 1.53-inch overall loaded length, plus proper headstamps and harder heads than most brass brands.