Monolithic Stubby
Do you use a rifle chambered in a so-called „big bore” cartridge and are considering switching from lead to monolithic bullets? The market offers only a limited selection in these calibers, but there are some options—such as the XPB bullets from Barnes.
Some hunters swear by so-called „big bore straight-wall" cartridges—those with straight-walled cases that lack a bottleneck and are loaded with heavy, large-diameter bullets. Examples include .450 Bushmaster, .44 Magnum, and .45-70 Government. Due to their pronounced ballistic arc, these rounds are not ideal for long-range shooting. However, they offer advantages such as reduced meat damage, lower penetration depth, and less ricochet risk, making them safer for hunting in certain environments. Their terminal effect is generally “instant” and less dependent on impact velocity than bottlenecked cartridges. While not a universal solution, these cartridges can be a great alternative for driven hunts and other specific hunting scenarios. However, hunters who wish to pair these calibers with increasingly popular monolithic bullets face limited options. The majority of monolithic bullet selections are geared towards .338-caliber rifles and below, while true „big bore" cartridges start at .429 caliber and up. Currently, the only available monolithic bullets for big bore straight-wall cartridges on the market come from the renowned manufacturer Barnes. These include a limited selection of calibers from the Banded Solid RN and TTSX series, as well as a broader range of options from the TAC-XP and XPB product lines, which we will explore in this article.
Additionally, Barnes also offers factory-loaded ammunition featuring XPB bullets, although the selection is limited. Specifically, they offer .44 Magnum 225gr and .454 Casull 250gr, available for purchase at 79 CZK per round (proarms.cz).
Title photo: XPB bullets in .429/225 gr variant.
One of the Few
The XPB designation refers to a line of solid copper monolithic bullets—no lead whatsoever! At first glance, these bullets stand out due to their large expansion cavity, a specialized design marketed by the manufacturer as "X Bullet Technology," and a single crimp groove around the circumference. The crimp groove is notably deep, allowing for a firm crimp on the case mouth without deforming the bullet, which is advantageous for pressure consistency during firing.
The XPB bullets are specifically designed for big bore straight-wall cartridges, as indicated by the available caliber selection. These include: .500 caliber – 375 gr, 325 gr, 275 gr; .475 caliber – 275 gr; .451 caliber – 250 gr, 225 gr, 200 gr; .429 caliber – 225 gr, 200 gr; .410 caliber – 180 gr; .357 caliber – 140 gr. For completeness, it's worth noting that the related Barnes TAC-XP FB bullet line is nearly identical but slightly more optimized for defensive use, covering calibers from .355 to .449.
I tested the XPB .429 caliber, 225-grain bullet in both .444 Marlin, fired from a Marlin lever-action rifle with a 470mm barrel, and in .44 Remington Magnum, fired from a Ruger Blackhawk revolver. The revolver test was primarily conducted to simulate terminal effects at lower impact velocities. These bullets are well-manufactured and can be safely used in lever-action rifles with tubular magazines. The material is extremely strong, ensuring no deformation during reloading or standard handling. The reloading process itself went smoothly, with one minor observation—the crimp groove is quite pronounced, making it difficult to apply a crimp outside of the designated groove. Adjusting seating depth beyond the crimp groove would require increasing overall cartridge length by 1.5mm or more. While this would be acceptable in a revolver, it could be problematic in a rifle, as the bullet might engage the rifling prematurely. To maintain standard cartridge length, my only variable for precision tuning was powder charge. As expected, best accuracy was achieved with near-max loads. My Marlin features a Micro-Groove rifling, which typically performs best at higher velocities. I loaded the cartridge with 40 grains of Lovex D060 powder, achieving a measured average velocity of 727 m/s and an energy of approximately 3,855 J.
The XPB is a monolithic bullet, immediately recognizable by its large expansion cavity.
At 100 meters, I achieved a five-shot group (out of six) measuring 32 mm. While not exceptional on paper, for this caliber, it's an excellent result and more than sufficient for hunting purposes. Outstanding Ballistics
The ballistic coefficient of the tested bullet is only .146, which, considering the caliber, is still slightly above average. In terms of accuracy, at 100 meters, I managed to group five out of six best shots within 32mm. While not exceptional on paper, it is more than sufficient for hunting purposes, and for this caliber, it is actually a very solid result.
I had limited opportunities to properly test terminal ballistics in the field, as I didn’t get many chances to hunt wild boar, which is where this type of cartridge naturally excels. However, I did take a roe deer doe at approximately 60 meters, and the result was outstanding. The animal dropped instantly, with a complete pass-through shot. The entry wound was about the size of a coin, while the exit wound was slightly larger with less clean edges but almost no bruising. The heart was practically destroyed beyond recognition.
Minimum Impact Velocity
The manufacturer does not specify a minimum impact velocity required for proper bullet expansion, but testing with a "lightly loaded" .44 Magnum round showed that expansion reliably occurs at 360 m/s. With my .444 Marlin load, this translates to an effective range of at least 250 meters, which is well beyond practical hunting distances. From a ballistics standpoint, if your rifle is zeroed at 100 meters, then at 200 meters, you’ll need to compensate for approximately 320 mm of bullet drop. With experience, this can be done by eye, though a BDC reticle in your scope would provide a more reliable solution. However, beyond 200 meters, bullet drop becomes too significant for practical use. This also comes with a safety advantage—at 350 meters, the bullet drops by more than 2 meters, meaning it will harmlessly embed into the ground much sooner than faster cartridges in common use today. For hunting within 200 meters, as is typical in European hunting regulations, these calibers have clear advantages in specific conditions.
Testing in Clay
For further testing, I used the trusted method of shooting into a sculptor’s clay block. The manufacturer boasts about high weight retention, and I can only confirm this. The recovered XPB and TAC-XP bullets lost barely 1 grain of weight, an insignificant amount. The expansion was textbook-perfect—the bullet opened immediately after impact, with the entire front section splitting into six massive, evenly shaped petals, all the way to the crimp groove. This doubled the bullet’s diameter. The wound cavity was extremely violent, creating a massive spherical void in the clay.
Tested into a block of clay with a cartridge in combination with a 9x19 mm cartridge. The wound profile was nearly identical, though the .44 Mag channel was significantly larger.
Conclusion
When it comes to technical drawbacks, there are very few. The crimp groove makes adjusting overall cartridge length slightly more difficult. Additionally, due to the absence of lead, these bullets are relatively long, which reduces the case capacity. This isn’t an issue in .444 Marlin or .45-70, where there’s plenty of case volume, but in .44 Magnum, especially when you can’t seat the bullet shallower to compensate, it does rob the cartridge of some performance. However, as we’ve seen, in practical use, this isn’t a major problem, and there’s always the option of using a lighter, shorter bullet. Otherwise, these are outstanding bullets. In terms of range performance, they are the best I have tested so far in this caliber.
The main obstacle to wider adoption will likely be the higher price, which ranges from 29.8 CZK per bullet for .375/125 gr, Up to 49.9 CZK per bullet for .500/325 gr. The tested .429/225 gr version costs 38.2 CZK per bullet. The packaging is unusual, as these bullets are sold in packs of 20. However, this is actually a plus, since if your firearm doesn’t perform well with them, you’re not stuck with a costly mistake. For big-game hunting, particularly large wild boar, these bullets will be an excellent choice. However, for high-volume culling of smaller animals, most hunters will likely stick with lead, at least for as long as it remains legal...
The XPB and TAC-XP bullet lines, along with other Barnes bullets, can be purchased at STROBL.cz s.r.o.. More information is available at strobl.cz or on the manufacturer’s website: barnesbullets.com.
Advantages/Disadvantages
+ Near-perfect weight retention
+ Excellent accuracy (for a "big bore" cartridge)
+ Textbook expansion, even at lower impact velocities
+ Best-performing bullet in this caliber that we’ve tested so far
- Higher price
A before-and-after comparison of the bullet. At an impact velocity of 360 m/s, it penetrated 50 cm of clay and embedded itself in a dense stack of magazines. The deformation is simply exemplary.Photo Sources: Author’s archive, manufacturer materials - nosler.com
Author: Tomáš Prachař
The article originally appeared in the magazine Lovec by Extra Publishing