.300 AAC Blackout Once-Fired Brass for Reloading
Our once-fired .300 AAC Blackout brass is sourced from range-fired ammunition, then mechanically sorted, cleaned, polished, hand sorted, inspected, and packaged for resale to reloaders.
Because this is mixed range brass, individual batches may include factory-manufactured .300 AAC Blackout cases, .223 Remington or 5.56 NATO cases that were previously converted to .300 Blackout, or a combination of both. The composition varies from batch to batch, and no specific percentage of factory-manufactured or converted cases is guaranteed.
The prior history and conversion method of individual converted cases are generally unknown. Converted cases may have been produced commercially or converted by an individual reloader before entering our supply stream. Customers should carefully inspect, resize, measure, and prepare every case before loading.
This brass is sold as mixed headstamp unless otherwise specified. Commercial cases, converted military 5.56 NATO cases, and other headstamps may appear depending on the source and composition of each batch.
Most .300 AAC Blackout brass uses Boxer primer pockets and Small Rifle primers. Spent primers are typically still in place. Primer-pocket crimps may or may not be present depending on the original case and its prior history.
Most once-fired brass orders include approximately 2–3% additional brass. Once-fired brass is a previously used product, and while we work hard to maintain high quality standards, no inspection process is perfect. We also recognize that every reloader's inspection standards and intended use may differ. Please see our Brass Information page for details regarding our overpack policy.
Product Summary
| Specification | Details |
|---|
| Cartridge | .300 AAC Blackout / 300 BLK / 7.62x35mm |
| Brass Type | Once-fired mixed range brass unless otherwise specified |
| Case Origin | May include factory-manufactured .300 Blackout cases, converted .223 Remington / 5.56 NATO cases, or both |
| Factory vs. Converted Mix | Varies by batch; no specific percentage of either type is guaranteed |
| Primer Type | Boxer unless specifically stated otherwise |
| Primer Size | Small Rifle in most cases |
| Headstamp | Mixed unless specifically stated otherwise |
| Primer Crimp | May or may not be present |
| Deprimed | No, unless specifically stated in the selected product option |
| Processing | Mechanically sorted by diameter and height, cleaned, polished, hand sorted, and inspected |
| Reloadable | Yes, when properly inspected and prepared by the reloader |
Common Uses for .300 AAC Blackout Brass
.300 AAC Blackout is a versatile rifle cartridge commonly used for:
- Supersonic rifle ammunition
- Subsonic rifle ammunition
- Hunting
- Target shooting
- Recreational shooting
- Tactical training
- AR-15 style rifle reloading
- Short-barreled rifle and pistol-platform ammunition
- Suppressed-firearm applications
- General-purpose ammunition
- Load development and testing
What Reloaders Say About Our .300 Blackout Brass
Our customers include hobby reloaders, hunters, recreational shooters, tactical shooters, and high-volume reloaders. Customer feedback commonly highlights cleanliness, fast shipping, consistency, and the overall quality of the brass received.
Read Customer Reviews
Quality Standards & Processing (Click to expand)
How We Process .300 AAC Blackout Brass
Our .300 AAC Blackout brass passes through multiple stages of mechanical sorting, cleaning, polishing, hand sorting, and inspection before being packaged for sale.
Incoming brass is first processed to remove loose debris and obvious contaminants. It is then mechanically sorted by body diameter to separate cases that do not belong in the intended sorting group.
The brass is subsequently mechanically sorted by case height. Diameter and height sorting work together to improve caliber separation and remove many incorrectly sized cases before the brass reaches the hand-inspection stage.
Most of our brass is then wet washed, rinsed, and finished in heated corncob media to improve appearance while helping preserve the brass during storage.
After mechanical sorting and cleaning, every batch is hand sorted and visually inspected. During this process, we remove incorrect calibers and cases showing split necks, severe corrosion, major physical damage, severely damaged rims, excessive discoloration, or other conditions that could affect reloadability.
Because factory-manufactured and converted .300 Blackout cases share the same general finished dimensions, both types may remain in the product after sorting. The presence and proportion of converted cases depend on the composition of the incoming brass and may vary considerably between batches.
Our Quality Standard
Once-fired brass is a previously used product, and every case has its own history. This is particularly important with .300 AAC Blackout because an individual case may have been manufactured as .300 Blackout or previously converted from a .223 Remington or 5.56 NATO case.
While no inspection process can identify every possible defect or determine the complete history of every case, our goal is to provide brass that we would be confident using ourselves.
Many inspection decisions rely on practical reloading experience rather than a simple checklist. If a case does not meet the quality standard we expect for our own reloading bench, we would rather remove it than ship it.
Regardless of where your brass is purchased, every reloader should thoroughly inspect every case before reloading. This is one of the most important steps in producing safe, reliable ammunition. While we work hard to identify and remove defective cases, once-fired brass is a previously used product and no inspection process can guarantee that every defect will be found. The final inspection should always be performed by the individual assembling the ammunition.
Most once-fired brass orders include approximately 2–3% additional brass. While this helps compensate for the occasional case that may not meet our quality standards or your individual expectations, it should never replace a careful inspection before loading.
For additional information about once-fired brass, inspection, primer crimps, flash holes, safety considerations, and our overpack policy, please visit our Brass Information page.
Technical Specifications (Click to expand)
.300 AAC Blackout Quick Specifications
The following information provides a practical reference for commonly checked .300 AAC Blackout cartridge and case dimensions. Always consult current published reloading data and official standards before loading ammunition.
| Specification | Reference |
|---|
| Cartridge | .300 AAC Blackout |
| Common Abbreviations | 300 BLK / 300 AAC BLK |
| Metric Designation | 7.62x35mm |
| Case Type | Rimless, bottleneck rifle case |
| Bullet Diameter | Approximately .308" |
| Maximum Case Length | 1.368" |
| Common Trim-To Length | Approximately 1.358" |
| Maximum Cartridge Overall Length | 2.260", depending on bullet and load specification |
| Typical Primer Size | Small Rifle |
| Primer Pocket Type | Boxer unless otherwise specified |
| Primer Crimp | May be present in converted military cases or other previously crimped brass |
| Common Parent Case | .223 Remington / 5.56x45mm NATO |
Official SAAMI Reference
For official cartridge and chamber drawings, dimensional tolerances, and pressure standards, consult the current SAAMI specifications for .300 AAC Blackout.
View Official SAAMI .300 AAC Blackout Specifications
Reloading Notes (Click to expand)
Preparing .300 AAC Blackout Brass for Reloading
Proper case preparation is an important part of producing safe, reliable, and consistent ammunition. While every reloader develops their own routine, inspecting, depriming, resizing, measuring, and preparing each case before loading is considered standard practice.
This brass has been sorted, cleaned, polished, and inspected, but it has not been fully processed for loading. Spent primers are typically still in place unless the selected product option specifically states otherwise.
Factory-Manufactured and Converted Brass
Mixed .300 AAC Blackout range brass may include cases originally manufactured as .300 Blackout and cases previously converted from .223 Remington or 5.56 NATO brass.
The amount of each type varies according to the incoming brass available for each batch. Some batches may contain converted cases, while others may contain little or none. No percentage of factory-manufactured or converted brass is guaranteed.
The prior conversion method and history of an individual converted case are generally unknown. Cases may have been converted commercially or by an individual reloader. Every case should therefore be resized, measured, and carefully inspected before loading.
Case Length and Trimming
Case length is especially important when preparing .300 AAC Blackout brass. Cases should be resized and then measured to verify that they remain within current published specifications.
The SAAMI maximum case length is 1.368 inches. Many reloaders use a trim-to length of approximately 1.358 inches, but every case should be measured and current published reloading data should be consulted before trimming.
Converted cases may exhibit greater variation in length than factory-manufactured cases because the original .223 Remington or 5.56 NATO case was cut and formed during conversion. The case mouth should be inspected, chamfered, and deburred as necessary.
Neck Inspection and Converted-Case Considerations
When .223 Remington or 5.56 NATO brass is converted to .300 Blackout, a portion of the original case body becomes the new case neck. Differences in parent-case construction can result in variations in neck-wall thickness.
Reloaders should inspect converted cases carefully and verify that their finished ammunition is compatible with the firearm, chamber, bullet, and loading practices being used. Reloaders who require closely matched brass may choose to sort cases by headstamp or case origin before load development.
Primer Pocket Inspection
Most .300 AAC Blackout brass uses Small Rifle primers. Mixed-headstamp brass should always be checked before priming.
Primer-pocket crimps may or may not be present. Converted cases made from military 5.56 NATO brass may retain a crimped primer pocket, but primer crimps can also be applied during other loading or manufacturing processes.
The presence of a primer crimp is not considered a defect. When present, it generally must be swaged or reamed before a new primer can be seated.
Headstamp Sorting
Our standard .300 AAC Blackout brass is sold as mixed headstamp unless otherwise specified. Headstamps may identify factory .300 Blackout brass or reflect the .223 Remington or 5.56 NATO parent case from which the brass was converted.
Many reloaders successfully use mixed brass for general shooting, hunting, and training. Reloaders seeking greater consistency may choose to sort cases by headstamp, manufacturer, case weight, internal volume, or apparent case origin.
Subsonic and Supersonic Loads
.300 AAC Blackout is commonly loaded with both subsonic and supersonic bullets. These loads can differ substantially in bullet weight, powder selection, operating pressure, firearm function, and intended use.
Always use current published load data that specifically matches the bullet, powder, primer, and firearm configuration being used. Never substitute load data based only on a similar-looking cartridge or bullet weight.
Case Life
The useful life of .300 AAC Blackout brass depends on factors such as chamber dimensions, load pressure, resizing practices, original case construction, prior conversion quality, and overall case condition.
Every case should be inspected before each loading and discarded if signs of failure, cracking, excessive wear, loose primer pockets, severe deformation, or other unsafe conditions are present.
Annealing
Some reloaders choose to anneal bottleneck rifle brass to help maintain consistent neck tension over multiple reloadings. Annealing is optional and should only be performed using proper equipment and accepted procedures.
For additional information about inspecting, preparing, and processing once-fired brass, please visit our Brass Information page.
Cartridge Information (Click to expand)
About the .300 AAC Blackout Cartridge
.300 AAC Blackout was developed to provide .30-caliber performance in the AR-15 platform while using a standard-size AR-15 bolt and magazines. The cartridge is commonly identified as .300 AAC Blackout, 300 BLK, or 7.62x35mm.
Its ability to support both lightweight supersonic bullets and heavy subsonic bullets has made it popular among hunters, recreational shooters, tactical shooters, suppressor users, and reloaders interested in developing ammunition for a wide range of applications.
Common Firearms Chambered in .300 AAC Blackout
.300 AAC Blackout is chambered in a variety of firearms, including:
- AR-15 style rifles
- AR-style pistols
- Short-barreled rifles
- Bolt-action rifles
- Single-shot rifles
- Hunting rifles
- Suppressed firearm platforms
Relationship to .223 Remington and 5.56 NATO Brass
.300 AAC Blackout was designed around a shortened and reshaped case based on the .223 Remington / 5.56 NATO case family. As a result, .223 and 5.56 cases are commonly converted into .300 Blackout brass.
The conversion process generally involves cutting the parent case, forming the new shoulder and neck, resizing the case, and trimming it to the appropriate length. The quality and details of prior conversion work can vary, which is why converted cases should always be carefully inspected and fully prepared by the reloader.
Factory and Converted Case Identification
Factory-manufactured .300 Blackout brass usually carries a headstamp identifying it as .300 Blackout or 300 BLK. Converted cases generally retain the original .223 Remington or 5.56 NATO headstamp of the parent case.
A .223 or 5.56 headstamp on a properly formed .300 Blackout case does not necessarily indicate a problem. It indicates that the case originated as another cartridge before being converted.
Because this product is mixed range brass, batches may contain factory cases, converted cases, or both. The composition varies, and no particular ratio is guaranteed.
Commercial and Military Parent Brass
Converted .300 Blackout cases may originate from commercial .223 Remington or military 5.56 NATO brass. Military parent cases may contain crimped primer pockets, although primer crimps are not exclusive to military brass.
Differences in case construction, internal capacity, brass hardness, neck thickness, and primer-pocket condition can occur between manufacturers and headstamps. These variations should be considered during case preparation and load development.
Subsonic and Supersonic Ammunition
.300 AAC Blackout is commonly loaded in two broad performance categories.
- Supersonic ammunition generally uses lighter bullets at higher velocities and is commonly selected for hunting, general-purpose shooting, and applications requiring greater velocity.
- Subsonic ammunition generally uses heavier bullets at velocities below the speed of sound and is frequently associated with suppressed shooting.
Not every firearm configuration will function reliably with every subsonic or supersonic load. Barrel length, gas-system design, suppressor use, bullet weight, and powder selection may all affect performance.
Preventing Cartridge Confusion
.300 AAC Blackout and .223 Remington / 5.56 NATO ammunition can be used in similar AR-platform magazines, but the cartridges are not interchangeable.
Reloaders and firearm owners should clearly label ammunition, magazines, storage containers, and loading components to prevent a .300 Blackout cartridge from being mistakenly placed into a firearm chambered for .223 Remington or 5.56 NATO.
For additional cartridge history, technical articles, and educational resources, visit our Reloading Knowledge Center as new content becomes available.
Frequently Asked Questions (Click to expand)
Frequently Asked Questions About .300 AAC Blackout Brass
Q: Is this .300 AAC Blackout brass deprimed?
A: No, unless specifically stated otherwise in the selected product option. In most cases, the spent primer remains in place.
Q: Is this factory-manufactured .300 Blackout brass?
A: It may be. Because this is mixed range brass, a batch may include factory-manufactured .300 Blackout cases, converted .223 Remington or 5.56 NATO cases, or a combination of both.
Q: Does this product contain converted .223 or 5.56 brass?
A: It may. The presence and quantity of converted cases depend on the composition of each incoming batch.
Q: What percentage of the brass is factory-made versus converted?
A: The percentage varies from batch to batch. We do not guarantee any specific percentage of factory-manufactured or converted cases.
Q: Who converted the .223 or 5.56 cases?
A: The prior history of individual range cases is generally unknown. Converted cases may have been produced commercially or converted by an individual reloader before entering our supply stream.
Q: How can I identify converted .300 Blackout brass?
A: Converted cases generally retain the original .223 Remington or 5.56 NATO headstamp. Factory-manufactured cases commonly carry a .300 Blackout or 300 BLK headstamp.
Q: Is converted .300 Blackout brass reloadable?
A: Yes, converted cases can generally be reloaded when they have been properly formed and are carefully inspected, resized, measured, and prepared. The final determination of whether an individual case is suitable for reloading must be made by the reloader.
Q: Is this brass sorted by headstamp?
A: No. Our standard .300 AAC Blackout brass is mixed headstamp unless the individual product title or description states otherwise.
Q: Is this brass Boxer primed?
A: Yes, unless specifically stated otherwise in the selected product option.
Q: What primer size does .300 AAC Blackout brass use?
A: Most .300 AAC Blackout brass uses Small Rifle primers. Reloaders should inspect each case and verify primer-pocket condition before priming.
Q: Will this brass have crimped primer pockets?
A: Primer-pocket crimps may or may not be present. Converted cases made from military 5.56 NATO brass may contain crimps, but crimps can also result from other manufacturing or reloading processes.
Q: Has the primer crimp been removed?
A: No crimp-removal service should be assumed unless the selected product option specifically states otherwise. Customers should inspect each primer pocket and swage or ream any crimp that is present.
Q: How is this .300 Blackout brass sorted?
A: It is mechanically sorted by body diameter, mechanically sorted by case height, then hand sorted and visually inspected before packaging.
Q: Has this brass been resized?
A: No, unless specifically stated otherwise. Customers should resize the brass using appropriate .300 AAC Blackout reloading dies before loading.
Q: Does .300 Blackout brass need to be trimmed?
A: Every case should be measured after resizing and trimmed when necessary to remain within current published specifications. Converted cases may exhibit greater initial case-length variation than factory-manufactured cases.
Q: What is the maximum case length for .300 AAC Blackout brass?
A: The SAAMI maximum case length is 1.368 inches.
Q: What is the common trim-to length for .300 AAC Blackout brass?
A: Many reloaders use a trim-to length of approximately 1.358 inches. Always consult current published reloading data and measure cases before trimming.
Q: Do converted cases require special inspection?
A: All once-fired cases require careful inspection. With converted brass, reloaders should pay particular attention to case length, shoulder formation, neck condition, neck-wall thickness, primer-pocket condition, and overall case dimensions.
Q: Can .223 Remington or 5.56 NATO brass be converted into .300 Blackout?
A: Yes. The .223 Remington / 5.56 NATO case is commonly used as the parent case for converted .300 Blackout brass. Proper conversion requires suitable tools, measurements, and case-preparation procedures.
Q: Can I use .223 Remington dies to resize .300 Blackout brass?
A: No. Finished .300 AAC Blackout cases should be resized using dies specifically intended for .300 AAC Blackout.
Q: Can I use .300 Blackout ammunition in a .223 Remington or 5.56 NATO firearm?
A: No. The cartridges are not interchangeable. A .300 Blackout cartridge must never be fired in a firearm chambered for .223 Remington or 5.56 NATO.
Q: Should I separate factory and converted cases?
A: Many reloaders use mixed brass successfully for general-purpose ammunition. Reloaders seeking greater consistency may choose to sort cases by headstamp, manufacturer, case weight, internal volume, or apparent case origin.
Q: Can this brass be used for both subsonic and supersonic loads?
A: Properly inspected and prepared .300 AAC Blackout brass may be used with published subsonic or supersonic load data. Always follow current data that matches the specific bullet, powder, primer, firearm, and intended application.
Q: How many times can .300 AAC Blackout brass be reloaded?
A: Case life varies according to the firearm, chamber dimensions, load pressure, resizing method, brass manufacturer, prior conversion history, and case condition. Every case must be inspected before each loading and discarded when signs of unsafe wear or damage are present.
Q: Why do you include extra brass?
A: Most once-fired brass orders include approximately 2–3% additional brass. Once-fired brass is a previously used product, and while we work hard to maintain high quality standards, no inspection process is perfect. We also recognize that every reloader's inspection standards and intended use may differ. Please see our Brass Information page for details regarding our overpack policy.
Q: Should I inspect every case before reloading?
A: Yes. Every case must be carefully inspected before loading, regardless of whether the brass is new, once-fired, factory-manufactured, or converted. The final inspection is the responsibility of the individual assembling the ammunition.
Q: Where can I learn more about once-fired brass?
A: Visit our Brass Information page for more information about inspection, primer crimps, flash holes, case preparation, safety, and our overpack policy.
