The Barra 400e is the most accurate BB gun ever tested by HAM. And now the company has introduced 400e barrel kits as a new upgrade option for this selective fire plinker.
In fact, there’s two kits: Standard and Precision Barrel Kits. These kits let you swap your rifle’s performance, whether that means optimizing for speed and accuracy with the Precision Barrel Kit or maximizing compatibility with bulk ammo using the Standard Barrel Kit.
Why Barrel Kits Matter
The Barra 400e has gone through a few different internal setups since its original launch. Over time, the company has shipped rifles with two different barrel types, each designed with a specific purpose in mind:
1. Standard Barrel. This is designed to be more forgiving with ammo, meaning it will reliably cycle a wide variety of steel BBs, even if they have slight differences in size, shape, or surface finish. Barra says this barrel is intended for casual plinking, long shooting sessions, and using bulk or mixed-brand BBs without worrying about jams.
2. Precision Barrel. Built to tighter internal tolerances, this delivers improved accuracy and higher velocity potential. However, these exacting specs mean it’s more sensitive to BB imperfections. Barra explains that – for best results – it should be paired with the company’s own Barra Zinc-Plated .177 Cal / 4.5mm BBs, which are precisely machined and polished for this barrel.
How to Know Which Barrel You Have Now
Because the 400e’s internals have changed over time, your current barrel type depends on both the model and when you purchased your rifle:
400e Metal
– May 2022 – June 2025: Came with Precision Barrel.
(This was the configuration tested by HAM.)
– July 2025 and later: Comes with Standard Barrel.
400e Polymer
– October 2024 – June 2025: Came with Precision Barrel.
– July 2025 and later: Comes with Standard Barrel.
But Aren’t All BBs The Same?
Well, actually, they’re not! Back in 2022, Hard Air Magazine ran a major, three-part series on BB accuracy. This included an investigation of the range of diameters and weights for multiple BB brands.
For this investigation, HAM Tester Doug Wall weighed and measured no less than 250 individual BBs from five different types. Thanks Doug!
The smallest diameter BB measured 4.35 mm in diameter. The largest 4.43 mm. That’s a difference of 1.8%.
The big difference actually came in the weights. The lightest BB weighed was 4.98 Grains, while the heaviest was 5.46 Grains. That’s a significant difference of 9.6%.
For example, here’s the weight distribution chart for the Crosman Copperhead BBs.
With a cyclic firing rate of 500 – 600 rounds per minute for the Barra 400e, it’s easy to see that such variations in BB size and weight – let alone surface finish – could have a big impact on the potential for jamming.
Hence the reason for Barra offering the two 400e Barrel Kits and their own BBs that are designed specifically for full-auto BB guns. (Sadly these were not available at the time the HAM survey was undertaken).
Most of the comparative BB weight and diameter data is included in Part Two of this series. Please check it out there for additional details.
Why 400e Barrel Kits Are Worth Considering
Barra says that, by matching your barrel type to your shooting style, you can:
– Avoid jams and feeding issues
– Improve accuracy if precision is your goal
– Expand ammo options if flexibility is your priority
– Customize the feel and performance of your rifle without replacing the whole gun
The kits are easy to install and come complete with written instructions. There’s also video instructions that you can see on the Barra site.
Where To Buy
Barra 400e Barrel Kits are available for $25.00 in the Barra online store.
Barra “full auto” BBs are $15.00 for a 6,000-count bottle in the Barra store.
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