The 45-70 Government was born as a black powder cartridge – 70 grains of black powder behind a 405-grain lead bullet. That is not just a footnote in firearms history. It is a living, breathing part of American shooting culture that thousands of handloaders practice every year. From Trapdoor Springfield owners shooting the cartridge exactly as it was designed, to BPCR (Black Powder Cartridge Rifle) competitors ringing steel at 500 meters, the original way of loading the 45-70 remains deeply relevant.
This article covers the practical side of loading the 45-70 with black powder and Pyrodex – granulation choices, proper case fill, wads, lubricant, load data, and the cleaning protocol that is absolutely non-negotiable if you want to keep your barrel alive. If you have ever been curious about stepping back to the original propellant, this is where you start.
The Original 1873 Army Load Explained
The U.S. Army adopted the 45-70 in 1873 with a straightforward specification – 70 grains of FFg black powder pushing a 405-grain lead bullet at roughly 1,350 fps from a Trapdoor Springfield’s 32.6-inch barrel. That load generated around 1,640 ft-lbs of muzzle energy, which was considered decisive for both military and frontier use. From a modern 22-inch barrel, expect closer to 1,200-1,250 fps, which still delivers meaningful energy for hunting and target work.
What makes this load so enduringly practical is its low peak pressure – approximately 21,000 PSI. That is well within the design limits of original Trapdoor actions, which should never be subjected to modern smokeless loads designed for Marlin or Ruger platforms. If you own a Trapdoor Springfield or a reproduction, the original 70-grain black powder load is not just historically correct – it is the safest and most appropriate ammunition you can feed it. Modern smokeless “Trapdoor safe” loads attempt to replicate this pressure range, but many shooters prefer to simply use the propellant the rifle was built around.
FFg vs. Fg – Choosing the Right Granulation
FFg is the standard granulation for 45-70 black powder loads and has been since the cartridge was adopted. The grain size of FFg produces a pressure curve well suited to the 45-70’s case volume and bore diameter. It ignites reliably, fills the case properly, and delivers consistent velocities without excessive pressure spikes. For the vast majority of 45-70 black powder shooting – whether historical recreation, hunting, or BPCR competition – FFg is the correct choice.
Fg (single F) is a coarser granulation sometimes used in larger bore cartridges and cannons. Some shooters experiment with Fg in the 45-70, and it can work, but it typically produces slightly lower velocities and less consistent ignition compared to FFg. On the other end, FFFg is too fast for the 45-70 and should not be used – it generates higher peak pressures than the cartridge needs and creates more fouling. One critical note for new black powder handloaders – black powder is measured by volume, not by weight. A volumetric measure set to 70 grains gives you 70 grains by volume. The actual weight will vary slightly depending on the brand and granulation, but volume is the correct and traditional method.
| Granulation | Suitable for 45-70? | Notes |
|---|---|---|
| Fg (coarse) | Marginal | Lower velocity, less consistent ignition |
| FFg (medium) | Yes – standard | Correct choice for nearly all 45-70 loads |
| FFFg (fine) | No | Too fast, excessive pressure, more fouling |
Pyrodex RS Loads and Volume Equivalency
Pyrodex RS (Rifle/Shotgun) is the most common black powder substitute used in 45-70 handloading, and it works well for shooters who find true black powder difficult to source or store. The key principle is simple – Pyrodex is loaded by volume to match black powder charges, not by weight. A volumetric charge of 70 grains of Pyrodex RS substitutes directly for 70 grains of FFg black powder. However, Pyrodex is lighter per unit volume, so the same volumetric charge will weigh less on a scale – typically around 55-58 grains by weight. Do not try to match black powder weight charges with Pyrodex. Use volume.
Pyrodex RS produces slightly less fouling than true black powder and generates comparable velocities and pressures when loaded volumetrically. Pyrodex Select is a premium version with tighter lot-to-lot consistency, which matters for competition shooters chasing small groups at long range. One important distinction – while Pyrodex fouling is somewhat less aggressive than true black powder residue, it is still corrosive and hygroscopic. The cleaning protocol remains essentially the same. Do not assume Pyrodex gives you a pass on post-shooting maintenance.
Wads, Lube, and Compressed Case Fill Tips
Compressed loads are completely normal with black powder in the 45-70 – in fact, they are expected and desirable. An uncompressed black powder charge can shift inside the case and lead to inconsistent ignition and erratic accuracy. Most properly loaded 45-70 black powder rounds compress the charge by 1/16 to 1/8 inch when the bullet is seated. A thin over-powder wad – typically a 0.060-inch vegetable fiber or lubricated card wad – sits between the powder charge and the bullet base. This wad serves two purposes: it prevents hot gas from cutting through bullet lube, and it helps scrape fouling from the bore with each shot.
Bullet lubricant is far more critical in black powder cartridges than in smokeless loads. Black powder fouling is a sticky, sulfur-laden residite that builds rapidly and hardens in the bore. Proper lube keeps fouling soft between shots, which is why BPCR competitors can fire 40 or more rounds without cleaning during a match. Look for lubricants specifically formulated for black powder use – SPG, Lyman Black Powder Gold, and traditional tallow-based lubes are all proven choices. The lube must fill every groove on the bullet generously. If you are casting your own bullets, designs with multiple wide lube grooves perform best.
Quick Checklist for Black Powder 45-70 Loading
- Use FFg black powder or Pyrodex RS measured by volume
- Seat a vegetable fiber or card wad over the powder charge
- Ensure the powder charge is lightly compressed when the bullet is seated
- Use a black powder-specific bullet lubricant – not standard smokeless lubes
- Use soft lead or lead alloy bullets – no jacketed bullets with black powder
- Verify no air gap exists between powder and wad
- Start with the historical 70gr FFg / 405gr load as your baseline
- Clean the bore the same day you shoot – no exceptions
- Store black powder in its original container, away from heat and sparks
- Keep a dedicated set of loading tools for black powder to avoid contamination
Common Mistakes With Black Powder 45-70
Even experienced smokeless handloaders make errors when transitioning to black powder. The propellant behaves differently and demands different habits.
- Measuring Pyrodex by weight instead of volume. This is the most common and most dangerous mistake. A weight-equivalent charge of Pyrodex will significantly exceed safe pressure levels. Always use volumetric measurement.
- Leaving an air gap in the case. Unlike smokeless powder, black powder must fill the case completely. An air gap between the powder charge and the bullet base can cause a dangerous pressure spike or a ringed chamber.
- Using smokeless bullet lubricant. Standard smokeless lubes do not keep black powder fouling soft. After a few shots, fouling hardens and accuracy collapses. Use lube designed for black powder.
- Neglecting same-day cleaning. Black powder fouling is hygroscopic – it pulls moisture from the air. A barrel left uncleaned overnight will show visible rust and pitting. Left for a week, the damage may be permanent. This is not an exaggeration.
- Using jacketed bullets. Black powder does not generate enough velocity to properly engage jacketed bullets, and the fouling buildup creates dangerous bore obstructions. Use plain lead or lead alloy bullets only.
- Assuming Pyrodex does not require cleaning. Pyrodex fouling is corrosive. The cleaning timeline is the same as true black powder – clean the same day, ideally within a few hours of shooting.
- Using FFFg granulation. Too fast, too much pressure, too much fouling. Stick with FFg.
Mandatory Cleaning Protocol
Clean your barrel the same day you shoot black powder or Pyrodex – within hours, not the next morning. Start with a hot water flush through the bore, which dissolves the water-soluble salts in black powder fouling. Follow with wet patches of a black powder solvent or a simple solution of hot water and dish soap. Run a bore brush, then dry patches until clean. Wipe down the bolt face, chamber, and any exposed metal that contacted fouling. Finish with a light coat of rust-preventive oil. This process takes 15-20 minutes and saves your barrel from irreversible damage.
FAQ – Black Powder and Pyrodex in 45-70
Can I shoot black powder loads in a modern Marlin or Henry 45-70?
Yes. Modern lever actions are built to handle pressures well above what black powder generates. The loads are safe in any firearm chambered in 45-70. The only consideration is that black powder fouling requires prompt cleaning, and lever action internals have more surfaces to clean than a single-shot rifle.
How do I know if my powder charge is properly compressed?
When you seat the bullet to the correct overall length, you should feel slight but firm resistance as the bullet base contacts the wad and compresses the powder column. Compression of 1/16 to 1/8 inch is typical. If the bullet drops in freely with no resistance, your charge is too light or you are missing a wad.
Is Pyrodex safer to store than black powder?
Pyrodex is classified differently for shipping and storage because it requires a hotter ignition source to detonate. It is somewhat more forgiving in storage than true black powder, but it should still be kept in a cool, dry location away from heat sources and open flame. Follow all manufacturer storage guidelines.
What velocity should I expect from the original 70-grain load?
From a 22-inch barrel, expect approximately 1,200-1,250 fps with a 405-grain bullet. From a longer 28-32 inch barrel typical of original Trapdoors and BPCR rifles, velocities climb to 1,300-1,350 fps. Chrono your loads – individual rifles vary.
Can I use black powder in 45-70 brass that has been fired with smokeless loads?
Yes, as long as the brass is clean and properly resized. There is no chemical incompatibility. Just ensure no smokeless powder residue remains in the case before loading with black powder.
What is BPCR competition and how do I get started?
Black Powder Cartridge Rifle silhouette is a competitive discipline where shooters engage metallic silhouettes at 200, 300, 385, and 500 meters using black powder cartridges. The 45-70 is one of the most popular chamberings. The annual Quigley Match in Montana is the largest and most well-known event. Local BPCR clubs exist across the United States and Canada – the NRA and BPCRA websites list affiliated matches and clubs where new shooters are welcome.
Quick Takeaways
- The original 70gr FFg / 405gr lead load remains safe, practical, and historically correct for any 45-70 firearm
- FFg is the standard granulation – do not use FFFg in the 45-70
- Pyrodex RS substitutes volume-for-volume for FFg black powder – never match by weight
- Compressed loads with an over-powder wad and proper black powder lube are essential for accuracy and bore health
- Clean your barrel the same day you shoot – black powder fouling causes pitting within hours if left unattended
- BPCR competition is a growing discipline and a natural home for 45-70 black powder shooters
- If you are shopping for supplies, look for dedicated black powder lubricants, vegetable fiber wads, and a reliable volumetric powder measure
