#Cartridges

Welcome to another of TFB’s Wheelgun Wednesday! In this week’s edition, we’ll touch on the 57 modern revolver cartridges that are in current production along with revolvers to shoot them. We always want to hear from our readers, but as the title suggests, we also want to hear what your favorite revolver cartridge is, so please join in on the comment section! Let’s explore the diversity of the 57 modern revolver cartridges.

If you are a precision rifle shooter, there should be very few reasons that shooters should have to pay over several dollars for a single piece of unfired brass. Unless you are a reloader that is. One of the really neat niches that I came across at SHOT 2018 was a company called RCC Brass based in Amarillo, Texas. RCC Brass machines cartridges from brass, instead of the traditional annealing process that shapes typical brass cartridges used throughout the entire world. They do this by taking a cold hammer forged 12-foot brass rod, cutting it to spec, and then machining the pieces of brass into the contours and specifications of whatever cartridge is required. One of the advantages is that there is no annealing that takes place throughout this entire process or is needed during the course of reloading the fired cartridges.

It’s not just the Yanks that are getting improved ammunition: Our friends across the pond have developed their own firepower upgrade for 5.56mm and 7.62mm weapons alike. Jane’s has a modest article on the subject, while The Register provides a quite good overview of exactly what the new rounds are and what they mean for today’s Tommy:

Today on an extra special episode of Historical Intermediate Calibers, we’ll be taking a look at one of the most controversial experimental military rounds, one that many believe should have become the standard for the Western World at the beginning of the Cold War. That round is the .280 British, also known as the 7x43mm, and beginning in 1947 it competed head-to-head against the caliber that eventually became the 7.62 NATO in trials to become the standard infantry small arms caliber of the free world. The .280 British has, in the almost 70 years since its invention, become one of the great “might-have-beens” of the small arms ammunition world. Many small arms enthusiasts wonder how firearms history might have been changed if this brilliantly designed British 7mm round had been adopted by NATO instead of the overlarge and too-powerful US-designed 7.62mm.

At this point we’ve looked at the data for seven intermediate calibers currently on the market, each of which is – one way or another – influencing the discussion around the question of what next generation military rifle caliber will be. Those rounds were: The 5.56mm NATO, the 7.62x39mm Soviet, the 6.8x43mm SPC, the 6.5x38mm Grendel, the .300 AAC Blackout, the 7.62×40 WT, and the .25-45 Sharps. Initially, I intended for this series to be limited to just these seven, and I picked them as a cross section of different concepts and schools of thought regarding the intermediate caliber problem. Now, however, I have decided to expand this discussion to other calibers, including the latest developments outside the West. I figure I’ll just handle the extra clunk this introduces by breaking up the final comparative discussion into segments, that way all the data is presented clearly, and there are more posts for my readers to chew on. Everyone is happy.

The paradigm was established by the 1870s: Future infantry combat would focus on a combination of entrenchment, and long-range concentrated fire from well-drilled units to defeat the enemy beyond his own effective range. The arms race for a smaller-caliber, lighter-weight cartridge accelerated, but it was the Americans and the British that would discover a need for an even higher performance round that could outmatch any fielded by their enemies. Two key conflicts were the Second Boer War, fought between the British Empire on one side and the Transvaal Republic and the Orange Free State on the other, and the Spanish-American War, fought by the United States versus the Kingdom of Spain, most importantly in Cuba and the Philippines. These two conflicts shared one common feature: The opposing sides of each were chiefly armed with advanced quick-loading 7x57mm caliber Mauser rifles, firing high-sectional density 173gr round-nosed bullets at a nearly 350 ft/s muzzle velocity advantage versus the .303 and .30 caliber rounds fired by the British and Americans.

Almost four decades before the invention of smokeless powder, the advent of the Minié ball bullet made practical the standard infantry rifle, and with it the elongated projectile. This changed the fundamental physics of infantry weapon ammunition design, allowing longer ranged weapons firing oblong, high sectional density projectiles of smaller and smaller caliber. The arrival of smokeless powder in the mid 1880s accelerated this arms race: New projectiles, clad, or “jacketed”, with a hard metal to withstand the forces of acceleration generated by a high-velocity smokeless gun, took these principles to their extreme. By the late 1880s, infantry weapon caliber had shrunk from the ~0.69″ of the roundball-firing smoothbore muskets to less than a third of an inch (~0.30″), and smaller calibers were continuing to be adopted as the arms race to the bottom accelerated.

One thing that seems apparent from the ARDEC presentation on the CTSAS program is the excessive capability and weight of the 6.5mm CT ammunition, as well as its use of lead-cored projectiles as opposed to more modern (and less dense) EPR-type projectiles. Further, the 6.5mm configuration explicitly uses the same case as the 7.62mm CT round, to allow for shorter development times. These facts together indicate that the 6.5mm CT round demonstrated in the ARDEC presentation is not well optimized for minimum weight. For this post, we’ll create an estimate of a new, lighter round that still should be powerful enough to replace both 5.56mm and 7.62mm as a universal caliber. As mentioned in the previous post, we’ll call it the “LW 6.5mm CT” to differentiate it from ARDEC’s 6.5mm CT round.

Recently, I wrote an editorial regarding the LSAT/CTSAS team’s NDIA presentation on their 6.5mm cased telescoped carbine and machine gun concepts. There was a lot to say about the history of Army programs and the pitfalls facing that team, but today I want to get down to brass tacks and explore the weight savings and/or penalty of issuing to the infantry platoon the 6.5mm CT cartridge Phillips’ team proposed. Like in my November of 2013 article on the general purpose cartridge concept, I will be using the loads reported in the paper The Modern Warrior’s Combat Load, released in 2003. That paper is a little dated, unfortunately, but it’s the most comprehensive survey of the platoon’s loadout of which I am aware.

One of the most criminally ignored elements of military small arms ammunition in the casual discourse is weight. Despite being one of the most important elements from a logistical and human factors perspective, the subject of weight rarely comes up in discussions about ammunition, with those conversations tending towards sexier topics like muzzle energy, caliber, and “flash figures” like bullet weight and muzzle velocity.

A few years ago I found myself embroiled in an ammo debate – okay, an argument – with someone about .40 S&W versus 10mm. No, this was not a discussion involving name-calling of the .40 S&W or a talk about wound cavities, recoil, or, well, anything. It actually had to do with the cartridges themselves and the dimensions of the barrels of guns chambered in them. I finally abandoned the argument, but I’ve never forgotten. You guys have undoubtedly had numerous “discussions” about ammo and its interchangeability – or lack thereof – over the years, with varying degrees of success.

Those who frequent AR-15.com’s ammunition section or the IAA forums probably already know about poster wolfganggross and his excellent ammo cutaways, but for the rest, you’re in for a treat. Below are some samples of his high quality cutaways, exposing the innards of common and uncommon rounds alike:

The metallic cartridge case underwent significant – though difficult to see – changes in the period between 1860 and 1945. Case metallurgy, manufacturing methods, priming configurations, and even the basic configuration of the metallic case changed and matured during those years. One of the now antiquated methods for making cartridge cases is the subject of a recent Historical Firearms Blog post, featuring plates illustrating the process of drawing brass from a disk into a tubular cartridge case:

IAA Forum user PaulSmith  received several x-ray images of ammunition, and was able to take photographs:

Good news for hunters who want to stay quiet and don’t want to handload. SilencerCo, who achieved e-fame with the “Wizard Staff”, “Johnny Dronehunter”, and “The Silencing” promotional videos (and who also make silencers) have announced their own line of subsonic hunting ammunition, called simply “Harvester”. From the press release: