Published: May 2026 | Last updated: May 2026
The CCI No. 35 exists for one cartridge: the 50 BMG. Everything about this primer – its physical size, its output energy, its cup thickness, its priming compound charge – was engineered around the ignition requirements of a cartridge that operates at 55,000 PSI with case capacity measuring in the hundreds of grains of water. There is no other primer in civilian reloading that does what the No. 35 does, and there is no substitute that safely delivers equivalent performance in the 50 BMG application.
For most reloaders, the 50 BMG is a peripheral curiosity. For the community of long-range precision shooters, military-surplus equipment hobbyists, and extreme long-range competitors who actually reload this cartridge, the CCI No. 35 is not a specialty item – it is a consumable that belongs on the loading bench alongside the powder scale and the seating die. This article covers what the No. 35 is, why the 50 BMG requires its own primer format, and how to select and use it correctly.
Technical Specifications
| Feature | Specification |
|---|---|
| Manufacturer | CCI (Vista Outdoor, Lewiston, Idaho) |
| Primer Size | 50 BMG (0.315-inch diameter) |
| Category | Large Rifle – 50 BMG Specific |
| Output Level | High (designed for large case volume) |
| Cup Diameter | 0.315 inch |
| Packaging | 500-count boxes |
| Intended Cartridge | 50 Browning Machine Gun (50 BMG / 12.7x99mm) |
| Not Suitable For | Any other cartridge; no civilian non-BMG application |
| Related CCI Primers | CCI 200, CCI 250, CCI BR-2 |
The 0.315-inch cup diameter of the No. 35 is physically larger than any standard rifle primer. Standard Large Rifle primers measure 0.210 inches in diameter. The No. 35 is 50 percent larger in diameter – it will not fit in any standard primer pocket, and attempting to seat it in a standard case would damage the case and create an unsafe condition. This is not a primer that can be accidentally used in the wrong cartridge; it simply will not seat.
CCI packages the No. 35 in 500-count boxes rather than the 100-count trays standard for other primer sizes. This reflects the nature of 50 BMG loading: serious users load in volume, and primer-per-round costs are a fraction of the cost of the brass, powder, and projectile.
Why the 50 BMG Needs Its Own Primer
The 50 BMG is not merely a large cartridge – it represents a fundamentally different scale of ballistic engineering from any standard rifle cartridge. Understanding why it requires a unique primer requires understanding the ignition challenge it presents.
A 308 Winchester case holds approximately 56 grains of water. A standard CCI 200 primer provides enough energy to reliably ignite 40-50 grains of powder in that case volume. The 50 BMG holds approximately 290 grains of water – more than five times the case capacity. Maximum powder charges in published 50 BMG data run from 230 to 260 grains of powder. Slow-burning powders specifically formulated for the 50 BMG application – Hodgdon H50BMG, Hodgdon US 869, Alliant Reloder 50 – require substantial initial energy to ignite completely and uniformly in a case this large.
A standard Large Rifle Magnum primer – the CCI 250 or Federal 215 – produces several times more energy than the standard CCI 200. The CCI No. 35 produces substantially more energy still, specifically calibrated to the ignition demands of 250+ grain powder charges in a case with nearly 300 grains of water capacity. An underenergized primer in a 50 BMG load does not just produce inconsistent ignition – it can leave partially burned powder in the case, create significant pressure variations between rounds, and in worst cases produce a hangfire where the charge ignites after a delay that the shooter may not recognize as abnormal.
The No. 35’s cup thickness is also engineered for the 50 BMG’s operating pressure and the mechanical requirements of military-derived actions. M2 and M107 platforms, Barrett rifles, and similar semi-auto designs have firing pin geometry that requires a primer capable of handling both the firing pin strike and the sustained pressure of a 55,000 PSI round without cratering or piercing. The No. 35 meets that requirement at a scale no standard primer cup is designed for.
50 BMG Powder Pairings
Published 50 BMG recipe data specifies the CCI No. 35 as the reference primer across all major data sources. There is no meaningful choice between primer brands in this category – the No. 35 is functionally the only civilian 50 BMG primer available in the North American reloading market.
| Powder | Charge Range (grains) | Notes |
|---|---|---|
| Hodgdon H50BMG | 225-250 | Purpose-built for 50 BMG; primary powder choice |
| Hodgdon US 869 | 220-245 | Slow spherical; excellent metering; popular choice |
| Alliant Reloder 50 | 225-255 | Designed specifically for 50 BMG |
| Alliant Reloder 33 | 215-240 | Very slow extruded; 50 BMG application data available |
| Vihtavuori 24N41 | 230-255 | Finnish slow powder; clean-burning; precision applications |
| Vihtavuori 20N29 | 235-260 | Very slow; Vihtavuori’s dedicated 50 BMG powder |
| Hodgdon Retumbo | 215-235 | Slower magnum powder; some 50 BMG data available |
| Hodgdon H1000 | 200-220 | Faster than purpose-built 50 BMG powders; verify data |
| Ramshot LRT | 220-245 | Long-range taper powder; 50 BMG data published |
| IMR 8133 Enduron | 225-250 | Temperature-insensitive Enduron; growing data availability |
Always start 10 percent below published maximum charge weights and work up, watching for pressure signs. 50 BMG pressure signs – primer cratering, flattening, case head expansion – are the same signs monitored in any rifle cartridge but at a scale that makes them easier to see. At 250+ grain charges, a pressure excursion is not subtle.
Hodgdon H50BMG is the most purpose-designed powder for this cartridge and the one with the deepest available recipe data. Hodgdon US 869 is the spherical alternative favored by reloaders who use rotary or drum-style powder measures, as it meters more consistently than extruded powders at large charge weights.
50 BMG Reloading Considerations
Loading the 50 BMG differs from standard rifle reloading in several practical ways that affect how the CCI No. 35 is used.
Press Requirements – Standard single-stage presses are not rated for 50 BMG sizing and seating forces. A purpose-built 50 BMG press or a heavy-duty single-stage rated for the application is required. The primer seating station on these presses handles the No. 35 natively; do not attempt to seat a No. 35 in a standard primer-size seating punch.
Primer Pocket Preparation – 50 BMG brass from Lake City, Hornady, and other manufacturers is produced with tight primer pockets to military specifications. New brass may require primer pocket reaming or swaging before the No. 35 seats correctly. An improperly prepared pocket produces inconsistent seating depth, which directly affects ignition consistency.
Seating Depth – Seat the No. 35 flush to 0.005 inches below flush, consistent with standard primer seating practice. The scale of the primer makes seating depth variation more visible than with standard primers – use a dedicated gauge if loading for precision applications.
Semi-Auto Platforms – Barrett M107 and similar semi-auto 50 BMG platforms have free-floating firing pins by design, similar to AR-15s. The No. 35’s cup is designed to handle this application, but verify that your specific platform and load combination produces no slam-fire indications during break-in loads. Military surplus brass may have crimped primer pockets requiring swaging or reaming before the No. 35 seats properly.
Case Preparation – 50 BMG brass is expensive relative to standard rifle brass. Thorough case preparation – primer pocket cleaning, flash hole deburring, case length trimming, and neck annealing at appropriate intervals – is standard practice for serious 50 BMG reloaders. The CCI No. 35‘s consistent output is partly wasted if primer pockets are not uniformed to consistent depth across a batch.
Ballistic Context
The 50 BMG cartridge produces approximately 13,000 to 15,000 foot-pounds of muzzle energy with 647-750 grain projectiles at 2,700-2,900 fps from a 29-inch barrel. At 1,000 yards it retains more energy than many hunting cartridges produce at the muzzle. It is primarily used in three civilian applications:
- Extreme long-range target shooting – 1,000 to 2,000+ yard competition and informal long-range shooting
- Military surplus platform shooting – M2 Browning, M107, and similar semi-auto rifles in sporting and collector use
- Anti-materiel applications – where legal, for targets that require terminal performance beyond standard rifle cartridges
Reloading for any of these applications begins with the CCI No. 35 and one of the purpose-designed 50 BMG powders. There is no shortcut in the primer selection: the wrong primer in a 50 BMG case produces either unreliable ignition or a pressure condition. The No. 35 is the correct primer, it is widely available, and it should be the only primer considered for this application.
FAQ
Is there any other civilian 50 BMG primer besides the CCI No. 35?
The CCI No. 35 is the standard civilian 50 BMG primer in North America. Some competitive long-range shooters have used military surplus 50 BMG primers from demilled components, but these are not commercially available in the standard reloading supply chain. For practical reloading purposes, the No. 35 is the answer.
Can I use a large rifle magnum primer like the CCI 250 in 50 BMG brass to save money?
No. A standard Large Rifle Magnum primer will not fit in a 50 BMG primer pocket – the pocket diameter is 0.315 inches versus 0.210 inches for standard large rifle primers. The No. 35 must be used. There is no workaround and no substitute.
Does the CCI No. 35 work in all 50 BMG brass brands?
It is compatible with all major 50 BMG brass including Lake City, Hornady, and commercial headstamps. Military brass frequently has crimped primer pockets that must be swaged or reamed before seating. Always prepare primer pockets to consistent dimensions before loading.
What is the shelf life of the CCI No. 35?
Standard primer storage conditions apply: cool, dry location in original packaging. CCI primers stored correctly have demonstrated reliable ignition after decades of storage. The No. 35 is no different from other CCI primers in this regard.
Is 50 BMG reloading cost-effective?
The economics are favorable compared to factory ammunition at typical 50 BMG retail pricing. Factory 50 BMG ammunition ranges from $4 to $10 or more per round. Handloaded ammunition using once-fired brass, the CCI No. 35, and purpose-designed powder can reduce per-round cost significantly at volume. The initial investment in a compatible press and dies is substantial, but amortizes quickly for active shooters.
Conclusion
The CCI No. 35 is a purpose-built component for a purpose-built cartridge. There is nothing general-purpose about it, no adjacent application it might serve, and no substitute for it in the 50 BMG loading context. What it provides is reliable, consistent ignition of the massive powder charges that make the 50 BMG the cartridge it is – charges that no standard primer format approaches in energy requirements. For the reloader who loads this cartridge seriously, the No. 35 is a non-negotiable starting point and an entirely dependable one.
Editorial note: Originally published May 2026. This article was written from scratch as a new addition to the primer section of myreloading.com. Sections cover CCI No. 35 specifications and the physical uniqueness of the 50 BMG primer format, an engineering explanation of why the cartridge requires its own primer category, a ten-powder pairing table covering all major 50 BMG powders, 50 BMG-specific reloading considerations including press requirements and primer pocket preparation, ballistic context for the cartridge’s three primary civilian applications, and a five-question FAQ.
