Published: November 2025 | Last updated: June 2026
Disclaimer: All load data referenced in this article is drawn from published manufacturer sources. Always consult a current reloading manual before developing any load. Start below published minimums and watch for pressure signs.
There are single-stage presses designed for general-purpose reloading, and there are single-stage presses designed for the specific loading tasks that other presses handle poorly. The Redding Ultramag belongs clearly in the second category. Its 4-1/8-inch ram stroke, 4-3/4-inch frame opening, compound leverage linkage, and heavy-duty cast iron frame exist to solve problems that arise at the extreme end of the single-stage reloading spectrum: full-length sizing of 50 BMG brass, reforming large-capacity belted magnum cases, forming wildcat brass from parent cases that require significant force, and seating bullets in 338 Lapua Magnum or .408 CheyTac cases with heavy projectiles against stiff necks.
For a reloader whose primary applications sit within those parameters, the Ultramag is the press that handles them with the leverage and frame rigidity to make the work feel manageable rather than exhausting. For a reloader who sizes 308 Winchester or 6.5 Creedmoor for hunting and 9mm Luger for practice, the Ultramag’s capabilities exceed the application by a significant margin – and the money is better spent on the RCBS Rock Chucker Supreme or Forster Co-Ax.
Knowing which side of that line you’re on is the entire purchasing decision.
What’s in the Box
The Redding Ultramag ships with:
- Redding Ultramag press with standard 7/8-14 die threads
- Operating handle with steel shank and ball knob
- Primer arm assembly with large and small primer cups
- Spent-primer catcher with tube
- Printed instructions and warranty information
What’s not included: bench mounting hardware, shellholders, dies, or case lube. This is consistent with premium single-stage press practice – the press ships as a platform, and all caliber-specific tooling is sourced separately. For the Ultramag’s primary applications, the Redding Deluxe Rifle Die Set with a micrometer-adjustable seating die is the natural companion for large caliber work.
The Frame Design: What “C-Frame Access, O-Frame Strength” Actually Means
The Ultramag’s frame is described as combining C-frame access with O-frame strength – a claim that deserves unpacking rather than accepting at face value, because C-frames and O-frames are generally considered to make opposite tradeoffs.
A traditional O-frame is a closed loop: the ram and die head are connected by a rigid loop on both sides, which prevents the frame from opening under load. This geometry is inherently rigid under large sizing forces because the load path is fully enclosed. The drawback is limited visibility and hand access at the die area.
A traditional C-frame opens one side of the loop for better access to the die and shellholder. This visibility advantage comes at the cost of frame rigidity under heavy loads – the open side can spread slightly when the sizing force is high, which affects die alignment.
The Ultramag’s swept-link frame uses a compound linkage arrangement that gives the ram a longer travel path and provides better access to the working area than a conventional closed O-frame – which is where the “C-frame access” part of the description comes from. The frame walls themselves remain substantial cast iron on both sides, which is where the “O-frame strength” part originates. The engineering goal is to give an experienced reloader working with very large cases – 50 BMG, 338 Lapua Magnum, .408 CheyTac – better sight lines and hand clearance while maintaining the frame mass and geometry needed to resist deflection under extreme loads.
The practical result is a press that experienced long-range and extreme-caliber reloaders consistently describe as easier to work with on large cases than conventional O-frame presses, without giving up the rigidity that heavy sizing operations require. A 50 BMG case is 4 inches long and requires the operator to guide it into the die correctly on each stroke – better visibility at the die entry matters in a way that it doesn’t for a 1.5-inch pistol case.
The Compound Leverage System
The Ultramag’s compound linkage is the other engineering feature that defines the press. Standard reloading press handles provide a direct mechanical advantage through a pivot at one point – the force you apply to the handle is multiplied by the handle length relative to the ram travel. The longer the handle and the shorter the ram travel, the higher the mechanical advantage.
The Ultramag’s compound linkage adds an additional mechanical stage to that force multiplication. The linkage connects the handle to the ram through two pivot points rather than one, which increases the mechanical advantage at the critical point in the stroke where sizing force peaks – at the bottom of the downstroke where the case is fully engaged in the sizing die. This is exactly where it’s needed for heavy case forming work.
The practical experience from users who work with 50 BMG and very large magnum brass consistently describes the Ultramag’s compound leverage as making those sizing operations feel lighter than the same work on a conventional single-stage press. Sizing a batch of 50 BMG brass on the Ultramag is a sustainable, manageable task. Sizing the same brass on an RCBS Rock Chucker Supreme requires more physical effort to deliver the same force. For a reloader who loads 50 BMG for long-range shooting or 1000-yard competition, that difference in session fatigue over 50-100 cases is real.
Key Specs and Compatibility
| Feature | Specification |
|---|---|
| Frame Type | Cast iron, compound swept-link (C-frame access, O-frame strength) |
| Frame Finish | Powder coat, corrosion and solvent resistant |
| Ram Diameter | 1 inch, steel, hollow for spent primers |
| Ram Stroke | 4-1/8 inches (usable) |
| Frame Opening | 4-3/4 inches |
| Leverage System | Compound linkage |
| Die Thread | Standard 7/8-14 |
| Shell Holder | RCBS, Redding, Lee compatible (standard format) |
| Primer System | Integral arm, large and small primer cups |
| Spent Primer | Through-ram disposal, integral catcher tube |
| Mounting | Three-hole base; quick-change system compatible |
| Max Caliber Covered | 50 BMG (4-3/4″ window confirmed) |
| Warranty | One-year limited against defects under normal use |
| Origin | Redding Reloading Equipment, USA |
The specifications that define the Ultramag’s application niche are the 4-1/8-inch stroke and 4-3/4-inch opening. For reference:
- RCBS Rock Chucker Supreme: 3.75-inch stroke, 4.25-inch opening
- Redding Big Boss II: 4-inch stroke, comparable opening
- Lee Classic Cast: 4-inch stroke, largest opening in the Lee lineup
- Redding Ultramag: 4-1/8-inch stroke, 4-3/4-inch opening
The Ultramag has the largest frame opening in this group by a clear margin. A 50 BMG case is approximately 4 inches long at the cartridge overall length – handling it in the press requires room to manage the case before it enters the die. The 4-3/4-inch opening makes this practical rather than awkward. On a press with a 4-inch or smaller opening, working with 50 BMG is possible but constrained.
The one-year limited warranty is the same limitation noted in the Redding T-7 Turret review – shorter than the lifetime coverage on RCBS, Lee, and Lyman single-stage presses. Redding’s construction quality is high and their service reputation is positive, but the warranty terms should be verified directly with Redding before purchasing.
Where the Ultramag Excels
50 BMG and extreme cartridge loading. This is the application the Ultramag was built for. The 4-3/4-inch frame opening accommodates 50 BMG case length without the case management issues that smaller presses create. The compound leverage makes full-length sizing of 50 BMG brass – which is large, thick, and requires sustained force – manageable across a full production batch. With CCI No. 35 primers and the appropriate die set, the Ultramag handles 50 BMG as a production workflow rather than a physical endurance test.
338 Lapua Magnum and comparable large belted magnums. 338 Lapua Magnum with Alliant Reloder 26, Alliant Reloder 33, or Vihtavuori N570 for long-range hunting and competition. The Ultramag’s frame opening, leverage, and cast-iron rigidity handle the 338 Lapua without the frame flex that affects smaller presses under that caliber’s full-length sizing force. Federal GM210M large rifle match primers and CCI BR-2 are the natural primer choices for this application.
Case forming and wildcat operations. Reforming brass from one case to another – necking down large cases, changing shoulder angles, fire-forming to a new chamber dimension – involves brass flow and die resistance that far exceeds the force of sizing a case to its standard specifications. The Ultramag’s compound leverage and frame rigidity make case forming work that would exhaust a standard single-stage press in a long session manageable over the full batch. For reloaders working with formation brass for wildcat cartridges derived from 300 Winchester Magnum or 338 Lapua Magnum parent cases, the Ultramag is the dedicated forming press.
Heavy magnum hunting load production. 300 Winchester Magnum with Hodgdon H1000 or Hodgdon Retumbo, 7mm Remington Magnum with Alliant Reloder 26 – the Ultramag handles sustained production of large magnum hunting loads at the sizing force level that these calibers require without the fatigue that standard presses develop over a 50-case batch. For pre-season load preparation where a hunter builds 100+ rounds of premium hunting ammunition, the Ultramag’s leverage advantage becomes practical over a long bench session.
Brass prep station for case hardening operations. Annealing and then full-length sizing large magnum brass from work-hardened once-fired cases generates the highest sizing forces in normal reloading practice. The Ultramag is the appropriate tool for this workflow, and its frame capacity keeps the operation controlled and consistent through a full batch.
Realistic Limitations
Overbuilt for standard calibers. 223 Remington, 308 Winchester, 6.5 Creedmoor, 30-06 Springfield – the Ultramag handles all of these, but it’s working at a fraction of its capability range. For a reloader whose calibers don’t push beyond 338 Lapua Magnum class, the Ultramag’s price premium over the RCBS Rock Chucker Supreme or Redding Big Boss II doesn’t buy meaningful improvement in the loaded round’s dimensional quality. The extra leverage is wasted on lighter loads. The extra opening is irrelevant for standard rifle cases.
Price and size. The Ultramag is one of the largest and most expensive single-stage presses available. If bench space is limited or the budget is constrained, the Ultramag’s specific capabilities need to justify both the cost and the footprint. For standard reloading applications, neither is justified.
One-year warranty. As noted in the specifications, Redding’s limited warranty on the Ultramag is one year. This is shorter than the lifetime coverage on the RCBS Rock Chucker Supreme, Lee Classic Cast, and other single-stage alternatives. Verify current warranty terms directly with Redding.
On-press priming sensitivity for heavy calibers. The integral primer arm handles standard primer seating adequately. For 50 BMG large rifle primers and the very large primer pockets of extreme cartridges, many Ultramag users prefer a dedicated hand priming tool – the RCBS Universal Hand Priming Tool or RCBS Hand Priming Tool – for better tactile feedback on primer seating depth. This is the same recommendation that applies to most single-stage presses for precision rifle loading.
Single-stage throughput. One completed case operation per handle stroke is inherent to single-stage design. For a reloader whose application is 50 BMG – where case count per session is typically small – this is irrelevant. For a reloader considering the Ultramag for 9mm Luger or 45 ACP volume work, the single-stage throughput combined with the Ultramag’s overkill construction makes no practical sense.
Setup and Mounting
Bench requirements. The Ultramag transmits very high forces into the bench during 50 BMG and case forming work. This requires the most robust mounting in the single-stage press category. Use 2-inch minimum hardwood, Grade 8 bolts with large-diameter washers through all three mounting holes, and position the press directly over a bench leg or structural support member. A bench that flexes under Ultramag load will reduce sizing consistency and can damage the bench surface over time.
Bolt-through mounting, not lag screws. For extreme case forming applications, lag screws into bench top material are not adequate – they can loosen or pull out under sustained high-force cycling. Bolt through the bench surface with threaded inserts or through-bolts and large washers on the underside. This is the mounting standard for any press doing sustained heavy work.
Die setup. Standard 7/8-14 dies install without adapters. For 338 Lapua Magnum and comparable calibers, the Redding Deluxe Rifle Die Set with micrometer seating die is the natural companion. For 50 BMG, dedicated 50 BMG die sets in standard 7/8-14 thread are available from multiple manufacturers. Use the how to tune a sizing die guide for sizing die position setup. Lock rings should be tightened firmly against the press head face – on the Ultramag with heavy sizing forces, a lock ring that has any play will shift position over a batch.
Primer system. Install the appropriate primer cup – the CCI No. 35 50 BMG primer is a standard large rifle primer that the large cup handles. For 338 Lapua Magnum with Federal GM210M or CCI BR-2 large rifle match primers, the large cup applies. For most users, a dedicated RCBS Universal Hand Priming Tool provides better seating feedback than the on-press arm for large magnum primers in critical hunting and competition applications.
Powder charging. The Ultramag’s primary calibers use large powder charges – 50 BMG runs 200+ grains of Hodgdon H50BMG per round, 338 Lapua runs 85-95 grains of Alliant Reloder 26 or Vihtavuori N570. The Redding Competition LR-1000 handles large charge bar requirements for magnum and extreme caliber work. For 50 BMG specifically, a dedicated 50 BMG-capable powder measure is required. Automated dispensers like the RCBS Chargemaster Supreme are calibrated for rifle charge weights but may need verification at the high end of their range for 200+ grain 50 BMG charges.
Case lube. For every bottleneck case on the Ultramag’s primary application list – 338 Lapua, 300 Winchester Magnum, 50 BMG – case lube is mandatory. The sizing forces involved in large case full-length sizing without lube are high enough to cause case head separation or die damage. Use case lube consistently on every case, with coverage on both the body and the neck. See the case prep essentials guide for the systematic approach.
Competitors – Four Direct Comparisons
RCBS Rock Chucker Supreme
The RCBS Rock Chucker Supreme is the O-frame single-stage press most often compared to the Ultramag for heavy-duty work. The Rock Chucker has a 3.75-inch stroke and a 4.25-inch opening – adequate for 338 Lapua Magnum and most large magnum calibers, but tight for 50 BMG class cartridges. Its priming system is smoother and better-regarded than the Ultramag’s integral arm. RCBS offers a limited lifetime warranty. The Rock Chucker doesn’t have the Ultramag’s compound leverage, which makes heavy case forming and 50 BMG sizing more physically demanding over a long session. For reloaders whose heaviest caliber is 338 Lapua Magnum or 300 Winchester Magnum, the Rock Chucker handles those calibers, has better warranty terms, and costs less. For 50 BMG and extreme case forming applications where the Ultramag’s larger opening and compound leverage are specifically needed, the Rock Chucker’s limitations become real.
Choose the Ultramag if: you specifically load 50 BMG or do extreme case forming work that requires the larger frame opening and compound leverage advantage. Choose the Rock Chucker Supreme if: your heaviest calibers are 338 Lapua Magnum class or below, the lifetime warranty is a priority, and the Rock Chucker’s 4.25-inch opening is sufficient for your case lengths.
Redding Big Boss II
The Redding Big Boss II is Redding’s precision single-stage press – machined steel frame, tight tolerances, the finest fixed-die runout performance Redding offers. It has a 4-inch stroke, which covers most large magnums, but its frame opening is smaller than the Ultramag’s 4-3/4 inches. The Big Boss II is the Redding precision instrument for the reloader who wants the best possible dimensional consistency from a fixed-die press and whose calibers are within the Big Boss II’s frame opening. The Ultramag is the Redding force instrument for reloaders who need maximum leverage and frame capacity for extreme cases. Between the two, the choice is whether your application requires precision (Big Boss II) or force capacity (Ultramag) as the primary criterion.
Choose the Ultramag if: frame opening for very large cases, compound leverage for extreme force applications, or 50 BMG capability are the priority. Choose the Big Boss II if: maximum precision from Redding’s machined steel construction is the priority and your calibers fit within its stroke and opening.
Lee Classic Cast
The Lee Classic Cast is the budget heavy-duty single-stage press – cast iron O-frame, 4-inch stroke, the largest opening in the Lee single-stage lineup, adjustable handle, and the lowest price in this comparison group. It handles 50 BMG with Lee’s conversion kit and covers the full range of large magnum calibers. What it doesn’t offer is the Ultramag’s compound leverage for heavy case forming work, and its cast iron construction, while solid, doesn’t match Redding’s build quality at the dimensional precision level. For a reloader who needs to work with 50 BMG or large magnums at a budget price, the Lee Classic Cast is a legitimate tool. For a reloader who does sustained high-force case forming work and wants the compound leverage to make that work less fatiguing, the Ultramag’s engineering advantage is real.
Choose the Ultramag if: the compound leverage advantage for sustained heavy case forming justifies the premium over the Lee, and Redding’s construction quality and the larger 4-3/4-inch opening are specifically needed. Choose the Lee Classic Cast if: you need large caliber capability and 50 BMG class work at a significantly lower price point, and the adjustable handle and maximum stroke length are valued over compound leverage.
Forster Co-Ax
The Forster Co-Ax is the precision alternative in the premium single-stage press category. Its coaxial floating die mechanism produces 0.001-inch runout – the best available from any single-stage press design. The Co-Ax handles 338 Lapua Magnum with its LS jaw set and 3.5-inch stroke, but it doesn’t have the Ultramag’s 4-1/8-inch stroke or 4-3/4-inch opening, and it doesn’t have compound leverage for sustained extreme case forming. The comparison between the Co-Ax and the Ultramag is a comparison between the two different things they excel at: the Co-Ax excels at precision (minimum runout), the Ultramag excels at force capacity (maximum leverage, largest case opening). For a reloader who loads 338 Lapua Magnum for precision long-range competition where runout is tracked, the Co-Ax’s 0.001-inch runout and 338 Lapua capability make it the more appropriate tool. For extreme case forming and 50 BMG, the Ultramag is the right press.
Choose the Ultramag if: maximum force capacity, 50 BMG capability, and sustained heavy case forming are the primary applications. Choose the Forster Co-Ax if: minimum runout through the floating die design is the primary goal and your calibers are within the Co-Ax’s LS jaw range.
Comparison Table
| Feature | Redding Ultramag | RCBS Rock Chucker Supreme | Redding Big Boss II | Lee Classic Cast | Forster Co-Ax |
|---|---|---|---|---|---|
| Frame Type | Cast iron, compound swept-link | Cast iron O-frame | Machined steel O-frame | Cast iron O-frame | Cast alloy, floating die |
| Ram Stroke | 4-1/8 in. | 3.75 in. | 4 in. | 4 in. | 3.5 in. |
| Frame Opening | 4-3/4 in. | 4.25 in. | ~4 in. | 4 in.+ | ~4 in. |
| 50 BMG Capable | Yes | Marginal | Marginal | Yes (with kit) | No |
| 338 Lapua Capable | Yes | Yes | Yes | Yes | Yes (LS jaws) |
| Compound Leverage | Yes | No | No | No | No |
| On-Press Priming | Yes | Yes (better feel) | Yes (best feel) | Yes | Top-mounted |
| Typical Runout | 0.002-0.003 in. | 0.002-0.003 in. | 0.001-0.002 in. | 0.003-0.005 in. | 0.001 in. (floating) |
| Warranty | 1-year limited | Lifetime limited | 1-year limited | Lifetime limited | Lifetime limited |
| Price Range | $$$ | $$ | $$$ | $ | $$$ |
| Primary Strength | Force capacity, 50 BMG | All-round heavy duty | Precision machining | Budget magnum | Minimum runout |
Real-World Use Notes
Reloaders who use the Ultramag for its intended applications – 50 BMG and large magnum case forming – consistently describe the compound leverage advantage as the press’s most impactful feature. Sizing work-hardened once-fired 338 Lapua Magnum brass from a hot barrel session requires force that wears you down on a standard single-stage press over 50 cases. On the Ultramag, the same batch requires noticeably less effort at the handle, and the session fatigue at the end of 50 cases is measurably less.
The visibility at the die entry area – the practical benefit of the hybrid frame design – matters when guiding long 50 BMG cases into the sizing die on each stroke. On a tighter O-frame opening, the operator has to feel the case into the die rather than see it. On the Ultramag’s 4-3/4-inch opening, there’s room to visually confirm the case is starting into the die straight before applying the sizing stroke. Over hundreds of cases, this reduces the “oops” moments of a case starting slightly canted that can damage the die or the case head.
For 300 Winchester Magnum and 7mm Remington Magnum hunters who go through 100+ rounds per hunting season and do a complete brass prep session each year – cleaning, sizing, trimming, and reloading – the Ultramag handles that workflow in one bench session without the fatigue that makes the same session uncomfortable on a standard single-stage. Check the case prep essentials guide for the complete brass prep workflow.
For 338 Lapua Magnum long-range hunting and competition, the Redding Competition LR-1000 handles the 85-95 grain Alliant Reloder 33 charges. Verify every charge on a RCBS Rangemaster 2000 or Frankford Arsenal Platinum Series scale before seating – for the overpressure considerations in large magnum cartridges, charge weight verification is not optional.
Troubleshooting
Stuck case during extreme case forming. This is the most severe failure mode for any heavy-duty single-stage press and is most likely to occur with the Ultramag’s application because case forming involves the highest forces of any normal reloading operation. Prevention is the only reliable solution: apply case lube to every forming case, re-apply between every stroke if forming requires multiple passes, and never attempt to form a case dry. If a case sticks, stop immediately. The extraction force available through the handle should not be used to attempt removal – it’s high enough to damage the case head. Contact Redding for guidance on stuck case removal on the Ultramag’s specific frame geometry before attempting any extraction.
Sizing inconsistency on large cases. Check bench mounting first – a bench that flexes under Ultramag load introduces sizing variability that the compound leverage mechanism can’t compensate for. Verify all mounting bolts are torqued properly. Second check the die lock ring is bearing firmly on the press head face without any float. Third verify case lube is applied consistently to every case – inconsistent lube application changes the sizing resistance and can affect the depth to which the die fully resizes the case.
Primer arm not reaching correct depth. For very large primer pockets – 50 BMG large rifle primers have dimensional tolerances different from standard large rifle – verify the primer arm depth adjustment is appropriate for the primer size. On the Ultramag, the primer arm position adjustment for extreme caliber primers may require more setup time than for standard rifle calibers. Most Ultramag users in this application use a dedicated hand primer tool and skip the on-press arm entirely.
Handle stiffness at the bottom of the stroke. The compound linkage’s geometry means the handle travel at the maximum force point feels different from a conventional single-stage press. If the handle feels rough rather than stiff, check the pivot pin lubrication. The compound linkage has multiple pivot points – all need regular light oil to cycle smoothly. Wipe the linkage area clean of powder residue and re-oil every session.
What to Buy with It
Die sets for primary calibers. For 338 Lapua Magnum, the Redding Deluxe Rifle Die Set with micrometer seating die is the Redding-ecosystem choice. The RCBS Competition Die Set is a compatible alternative. For case forming applications with Forster Bushing Bump Die Kits or similar bushing-controlled neck sizing dies, standard 7/8-14 thread compatibility means everything works on the Ultramag.
Hand priming tool. The RCBS Universal Hand Priming Tool for standard large rifle primers in 338 Lapua and 300 Winchester Magnum. For 50 BMG primers, a hand priming tool capable of handling the large rifle primer size delivers better seating feedback than the on-press arm.
Case lube system. A quality lube pad and RCBS Case Lube 2 or Hornady One-Shot for standard large magnum cases. For 50 BMG, a more thorough lube application method covering the full case body is important for consistent forming.
Powder measure for large charges. The Redding Competition LR-1000 handles charges above 50 grains appropriate for 338 Lapua and 300 Winchester Magnum at volume. For 50 BMG charges of 200+ grains, a dedicated 50 BMG powder measure is required. For automated dispensing, the RCBS Chargemaster Supreme handles standard rifle charge ranges.
Powder scale. The Frankford Arsenal Platinum Series Digital Scale or RCBS Rangemaster 2000 for charge verification. Every charge, every session, at the Ultramag’s primary caliber weights.
Concentricity gauge. For 338 Lapua and comparable precision long-range ammunition, a runout gauge confirms that case forming and sizing are producing consistent concentricity before bullets are seated.
Quick-change bench plate. If the Ultramag shares bench space with other equipment, a quick-change mounting plate allows it to be removed and reinstalled without re-bolting.
FAQ
Can the Ultramag actually load 50 BMG? Yes. The 4-3/4-inch frame opening accommodates 50 BMG case length, and the compound leverage handles the sizing force for that caliber. Dedicated 50 BMG die sets in standard 7/8-14 thread are available from multiple manufacturers. The CCI No. 35 50 BMG primer is a large rifle primer that the press’s standard primer arm handles.
Is the Ultramag worth its price for 308 Winchester and 6.5 Creedmoor loading? No. For 308 Winchester and 6.5 Creedmoor, the Ultramag’s capabilities exceed the application by a large margin. The RCBS Rock Chucker Supreme, Redding Big Boss II, or Forster Co-Ax are better-matched tools for those calibers at better price-to-capability ratios.
How does the compound leverage actually feel compared to a standard single-stage? Users consistently describe the Ultramag’s compound leverage as making heavy case forming feel noticeably lighter than the equivalent work on a standard single-stage press. At the bottom of the stroke – where sizing force peaks – the additional mechanical advantage reduces the handle force required for the same die work. Over a batch of 50-100 large magnum cases, the difference accumulates into measurably less session fatigue.
Why is the warranty only one year? This is Redding’s stated limited warranty for the Ultramag against defects in materials and workmanship under normal use. It’s the same one-year term as the Redding T-7 Turret. Redding’s construction quality is high and the Ultramag is built to outlast the warranty period by decades of normal use, but the warranty terms should be factored into the purchase decision alongside the press’s capabilities.
Can the Ultramag do case forming operations that would damage a lighter press? Yes, within the range of what’s physically achievable through a die. The Ultramag’s compound leverage and frame rigidity handle forming operations – necking large cases down to smaller diameters, changing shoulder angles, forming wildcat brass from large parent cases – that would be fatiguing and potentially damaging to lighter-duty single-stage presses under sustained high-force cycling. The key principle remains: lube every case, every time.
What’s the correct mounting approach for 50 BMG work? Bolt through the full bench surface with large-diameter washers on both top and bottom. 50 BMG sizing generates enough force that surface-screw or lag-bolt mounting is inadequate. Through-bolt mounting with backing hardware provides the clamping force and lateral resistance that sustained 50 BMG sizing demands.
Is the Ultramag compatible with Redding’s die sets? Yes. All Redding Deluxe Rifle Die Sets in standard 7/8-14 thread are compatible with the Ultramag without adapters. Redding’s bushing dies and neck sizing die sets are also directly compatible.
Conclusion
The Redding Ultramag is a press with a clear mandate and a specific audience. The compound leverage linkage, 4-1/8-inch stroke, 4-3/4-inch frame opening, and heavy-duty cast iron construction exist for reloaders who work at the extreme end of the single-stage press application spectrum: 50 BMG loading, sustained case forming at maximum force, large magnum brass preparation from work-hardened once-fired cases. For those applications, the Ultramag delivers what no other press in its price category provides.
For reloaders outside that specific application, the Ultramag is genuinely overbuilt. The RCBS Rock Chucker Supreme handles 338 Lapua Magnum and below with a lifetime warranty at a lower price. The Forster Co-Ax delivers 0.001-inch runout for precision-first applications in the same price tier. The Redding Big Boss II provides Redding’s precision machining with better warranty terms for standard large caliber work.
The Ultramag is not trying to be those presses. It’s trying to be the press that does what those presses can’t – and within that specific niche, it succeeds.
Choose the Redding Ultramag if you load 50 BMG, do sustained case forming work at the extreme end of the force spectrum, or regularly work with very large belted magnum cases where the compound leverage advantage and 4-3/4-inch frame opening represent a practical workflow improvement over conventional single-stage designs.
Choose the RCBS Rock Chucker Supreme instead if your heaviest caliber is 338 Lapua Magnum class or below, the lifetime warranty is a priority, and the Rock Chucker’s opening and stroke cover your case lengths.
Choose the Redding Big Boss II instead if Redding’s precision machining is what you want and your applications fit within the Big Boss II’s stroke and opening.
Choose the Lee Classic Cast instead if 50 BMG capability and large magnum work are needed at a budget price, and compound leverage is not a specific requirement.
Choose the Forster Co-Ax instead if minimum runout for precision long-range loading is the primary goal and your calibers are within the Co-Ax’s LS jaw range.
Editorial note: Originally published November 2025, revised June 2026. The revision expanded all sections from list-format to full prose, added a dedicated section explaining the compound swept-link frame design and what “C-frame access, O-frame strength” actually means mechanically, added specific explanation of the compound leverage system and its practical effect on session fatigue for heavy case forming, expanded all competitor comparisons with four head-to-head analyses and specific “Choose X if” guidance, and added full internal linking throughout including powder pages, primer pages, caliber guides, Redding die and measure pages, and related press reviews.
