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The Ultimate Reloading Manual
Wolfe Publishing Group
  • alliant reloading data
  • reloading brass
  • shotshell reloading
The Ultimate Reloading Manual
load development

Modern Handloads for the Classic .218 Mashburn Bee

Author: Patrick Meitin
Date: Nov 15 2022

The .218 Mashburn Bee test rifle was a Birmingham Small Arms (BSA) Martini single shot rebarreled with a heavy, 26-inch barrel and furnished with a gorgeous walnut forearm and buttstock.

The .218 Mashburn Bee is an “improved” version of the standard .218 Bee cartridge, including less case taper, lengthened chamber, sharper shoulder and shorter neck. These features increase velocity to the tune of 10 to 15 percent. Art Mashburn, a respected Oklahoma City gunsmith and owner of Mashburn Arms & Sporting Goods from 1941 to 1972, created the Mashburn Bee. Mashburn cases are fireformed from .218 Bee cartridges fired in a .218 Mashburn Bee chamber. Using fresh, factory ammunition or handloading new brass before fireforming minimizes shoulder and neck splits, though annealing older cases also does the trick. Factory .218 Bee ammunition and handloading cases are available from Hornady and Winchester, with Hornady seemingly the more reliable source today. Fireformed Winchester cases held about 17.1 grains of water filled to the brim, Hornady cases 19.2 grains. Mashburn case length matches the .218 Bee, at 1.340 inches. After fireforming you will likely find cases a touch short, but not to worry, they will function just fine.

Shown for comparison from left to right are; the .22 K-Hornet, Winchester .218 Bee, .218 Mashburn Bee and .221 Remington Fireball.

Load data for the .218 Mashburn Bee can prove scarce, with recipes including newer powders essentially nonexistent. Yet, .218 Bee data is commonly available. My basic approach was to begin with published .218 Bee data, creating my ladder chart, then adding 10 percent to each charge. Powders such as Alliant 2400, Hodgdon H-4198 and H-110 and IMR-4227 commonly appear in Bee data, while I added Vihtavuori N110 and N120, Hodgdon Lil’Gun and CFE BLK, Accurate 1680, Alliant Reloder 7 and Shooters World Blackout. For dependable temperature stability, I favor powders like H-4198 (a Hodgdon Extreme Series powder), CFE BLK (including a copper fouling eraser), the Vihtavuori formulas and Accurate 1680. Blackout charges were extrapolated from previous work conducted with the .218 Bee and that data was extrapolated from .300 Blackout/Accurate 1680 data.

Bullets used to test the .218 Mashburn Bee include, left to right,
Midsouth Shooters Supply 34-grain Varmint Nightmare,
Speer 40-grain Varmint Spire SP, Berger 40-grain Flat Base Varmint,
Sierra 45-grain Varminter Hornet SP and Hornady 50-grain Varmint SP SX.

While the Birmingham Small Arms Company (BSA) Martini test rifle certainly has a stout, and reliably safe single-shot action, their extractors are notoriously weak. This leads to sticky cases while shooting maximum loads. For this reason, listed powder charges remain conservative, with a few exceptions. Most of these loads could no doubt be pushed a bit farther from a solid bolt action – perhaps even this single shot – though I still encourage starting with the listed start loads and working upwards, while watching carefully for pressure signs. Remember, chamber dimensions can differ slightly in older wildcats such as the Mashburn Bee, resulting in wildly disparate chamber pressures.

The .218 Mashburn Bee test rifle was shot atop a sturdy
portable bench, supported by an MTM Case-Gard K-Zone Shooting Rest.

The British Empire made these rifles by the millions, and they were

The tightest group assembled with the 34-grain
Midsouth Shooters Supply Varmint
Nightmare bullet measured .93 inch
at 2,742 fps, using 13 grains of IMR-4227.

even used as reserve weapons in various colonies into World War II. This Martini was rebarreled with a heavy 26-inch barrel (.83 inch at muzzle) with, as best I can determine, a 1:14 rifling twist. The forearm and buttstock were created from fine, checkered walnut, with a thin rubber buttplate to provide an average 13½-inch length of pull. The forearm was carved wide to sit well on a rest, and the butt included a high, rollover comb. The trigger broke at crisp 1.75 pounds. A Hi-Lux SPG416x44MD (4-16x 44mm) scope mounted on a one-piece Weaver base was used during testing. The finished weight was 14 pounds.

I have shot many rebarreled Martinis, most relinquishing respectable varmint-grade accuracy. This, unfortunately, was not one of them. The rifle struggled to break an inch in most cases, with 1.5-inch groups deemed acceptable in this round of testing.

The tightest group of the entire Mashburn Bee test measured
.44 inch at 2,977 fps, using 16.5 grains of Alliant Reloder 7.

Cases were formed from WW-Winchester brass, and Winchester WSR primers were seated. Dies came from C-H Tool & Die/4-D Custom Die Company and an Area 419 ZERO Reloading Press was used to press all loads. All powder charges were carefully trickled onto a RCBS beam scale for maximum uniformity.

Bullets were chosen for small-varmint hunting, starting with Midsouth Shooters Supply 34-grain Varmint Nightmare and moving to Speer’s 40-grain Varmint Spire Soft Point, Berger’s 40-grain Flat Base Varmint, Sierra’s 45-grain Varminter Hornet and Hornady’s 50-grain SP SX (Soft Point, Super eXplosive). Ballistic coefficients are irreverent, as these squat bullets were designed to provide dismantling impacts on burrowing rodents at the velocities generated by this class of cartridge and its 250-yard maximum range.

The 34-grain Varmint Nightmare was selected as a short-range option to use in settled areas where ricochets might prove disastrous. They include a flatnose hollowpoint tip and are quite explosive on small varmints even from my .22 Hornet Taurus raging Hornet revolver. This bullet was paired with Vihtavuori and Hodgdon H-110 and IMR-4227, averaging a disappointing overall group size of 1.88 inch. All loads are loaded quite conservatively, as I viewed this as a short-range bullet. Vihtavuori’s N110 did best with a “maximum” load of 11 grains, printed 1.21 inches at 2,936 feet per second (fps), while H-110 did a little better with its 12-grain “start load,” printing 1.03 inches at 2,739 fps. IMR-4227 groups tightened with added powder, the “maximum” load of 13 grains produced the smallest group with this bullet; .93 inch at 2,742 fps.

Vihtavuori N120 with 13.5 grains, combined with a Speer 40-grain
Varmint Spire SP bullet produced this 1.13-inch group at 2,739,
the best with this bullet.

The Speer 40-grain was also paired with IMR-4227, with Hodgdon Lil’Gun and Vihtavuori N120 was added, producing a better overall group average of 1.60 inches. These loads were intentionally kept light, as I wished to compare relative accuracy to the hotter loads paired with the next 40-grain slug. Near 1-MOA groups were the best I would get out of this bullet, despite the lower overall group average. Lil’Gun proved unsurprisingly fast, posting velocities from 3,280 to 3,635 fps using 13 to 14 grains of powder – though the maximum load proved a touch sticky during extraction. Only the 13.5-grain charge produced a worthwhile group; 1.21 inches at 3,503 fps. IMR-4227 provided velocities matching the 34-grain bullet, 12 and 12.5 grains of powder producing groups close to an inch at velocities of 2,508 and 2,618 fps, respectively. Vihtavuori N120 gave a velocity boost, the 13.5-grain “start load” produced the best group with this bullet; 1.13 inches at 2,739 fps.

This .92-inch group was produced by 15.5 grains of Hodgdon
CFE BLK and Hornady’s50-grain Varmint SP SX
bullet. That group measured .92 inch at 2,810 fps.

Berger’s Flat Base Varmint was the most modern bullet design in the lineup, one of my favorites for ground squirrels with rounds like the .221 Remington Fireball. Accurate 1680, Vihtavuori N120 and Alliant Reloder 7 served as fuel, averaged 1.14-inch groups overall; heavily weighted by a fluke .44-inch group. As mentioned, these loads were pushed to higher velocities, hoping to get a better feel for this rifle’s performance preferences. Picking up the pace with the pointed bullet certainly reaped rewards. Fifteen grains of N120 produced a 1.21-inch group at a screaming 3,064 fps, while Accurate A-1680 broke an inch using a maximum load of 15.5 grains at 2,988 fps. The best group of the entire test resulted from a compressed load of 16.5 grains of Alliant Reloder 7 at .44 inch at a respectable 2,977 fps (the maximum load of 17 grains hitting 3,021 fps with a 1.22-inch group).

Sierra’s 45-grain Varminter Hornet SP seated over
16 grains of Hodgdon H-4198 produced the
best results with that bullet; .80 inch at 3,093 fps.

The heavier Sierra 45-grain Varminter Hornet introduced slower-burning Hodgdon 4198 and CFE BLK and a return to Lil’Gun. Combined, those powders averaged 1.51-inch groups. I seem to have cut back a bit too far with the Lil’Gun with this bullet, as it lost its velocity edge. Velocities of 2,603 to 2,731 were produced by 10 to 11 grains of powder, with the best group breaking an inch at 2,603 fps. Hodgdon’s CFE BLK produced excellent velocity, topping out at 3,092 fps with a maximum load of 17 grains and at least one decent group; 1.02 inches at 2,933 fps using the 16-grain “start load.” H-4198 also provided stellar velocity of 2,891 to 3,093 fps – the maximum load also producing an excellent .80-inch group.

Fifty grains are as far as I care to push cartridges in this class, though the thin-skinned 50-grain Hornady SP SX should offer ample varmint expansion at Mashburn velocities. The 50-grainer was paired with three “.300 AAC Blackout” powders; Accurate 1680, Shooters World Blackout and Hodgdon CFE BLK. All assembled groups averaged 1.72 inches. The heavy bullet produced some worthwhile groups, but also some of the test’s worst. A-1680 struggled with this bullet, with 1.29 inches at 2,594 fps its best effort, with things going off the rails with added powder. Shooters World Blackout deserves more experimentation, as it turned in some near-1-MOA to 1.20-inch groups with 15 and 15.5 grains of powder at 2,723 and 2,770 fps, respectively. CFE BLK proved the way to go with this bullet weight, printing .92 inch at 2,810 fps and 1.02 inches at 2,840 fps with 15.5 and 16 grains (maximum load) of powder.

My choices for combined maximum velocity and accuracy with this cartridge would be H-4198, Reloder 7 and CFE BLK, with A-1680 and Blackout and perhaps Lil’Gun deserving more attention.

It is always fun to experiment with previously untried cartridges, but in all honesty, the .218 Mashburn Bee seems like an answer to a question no one was asking. The Hornets remain the darlings of the mini-cartridges and will always remain so. Too, scrounging .218 Bee parent brass is becoming increasingly difficult. All in all, the .221 Remington Fireball makes more sense, offering slightly more velocity, more reliable accuracy and an inexhaustible supply of .223 Remington parent brass. Still, having more rifles is much more fun than having only a few, and the Mashburn Bee is certainly a fun option.