Many rifle powders introduced in the past few years contain decoppering agents, and not just the new IMR Enduron line and the recent Alliant Reloder powder 16, 23 and 26. All Vihtavuori rifle powders now include decoppering, though the announcement seems to have been missed amid the appearances of the newer powders.
Why is this happening? One guess might be the increasing popularity of long-range shooting, especially various target games, where a build-up of copper fouling in the bore can affect accuracy.
Then there's high volume varmint shooting, typified by prairie dogs, where several hundred rounds can be expended in one day. For many years the routine among PD shooters was to clean their rifle barrels at least once a day, often in the evening, accompanied by that other essential cleaning solvent, cold beer. This was partly because the job often took a long time, due to a heavy build-up of copper and quite a few cleaning solvents that didn't work all that quickly or well.
Some shooters avoided this by cleaning their bore every 50 rounds or so throughout the day, though often not all that successfully, again because the solvents and routine didn't really remove all the copper, or even most copper. It was more of a feel-good ritual--except for the fact that it often bypassed at 15-30 minutes of PD shooting.
Plenty of Campfire posts still obsess over rifle barrel cleaning, with long threads filled by opinions on the best solvent or cleaning routine. In these threads some shooters adamantly claim they've been using XYZ solvent for decades with perfect satisfaction, while others suggest a combination of 2-3 newer solvents, sometimes mixed together and sometimes applied separately. Then there are arguments over the "proper" bore-brushes and cleaning rods.
It would seem that with l this intense interest in bore-cleaning that many shooters would welcome powders with decoppering agents, yet often somebody expresses skepticism about decoppering powders. This sometimes includes suggesting they may just be another form of "snake oil," an unproven mystery ingredient designed to separate handloaders from their hard-earned money. A little skepticism is healthy for humans, but anybody who thinks decoppering agents are a new fad, or don't work, doesn't know much about the history of smokeless powder and copper.
The first practical smokeless rifle powder was developed in the early 1880s in France, and introduced in the new 8mm Lebel cartridge and bolt-action rifle adopted by the French military in 1886. Soon other countries followed, using variations on the same basic formula. However, all the new smokeless powders resulted in MUCH higher velocities for centerfire rifles than black powder, generally over 2000 fps, which in the next quarter of a century increased to 3000+ fps.
The plain lead bullets normally used with black powder were impractical, due to much of the lead stripping away inside the bore. The solution was a lead core inside a "jacket" of harder metal. The most practical jacket material turned out to be some sort of copper alloy.
However, this did not eliminate bore-fouling, and copper was much harder to remove than lead, especially from military weapons that were fired rapidly and repeatedly, from machine guns to artillery. In large-caliber artillery barrels, strips of copper from the rifling grooves sometimes emerged from the muzzle during a heavy barrage. Obviously this did not help accuracy.
Once again, the French apparently first came up with a solution, discovering that lead wire or foil placed on top of the powder charge vastly reduced or even eliminated copper-fouling. This discovery occurred before World War One, more than a century ago, so no, decoppering agents are not new, or unproven snake oil.
The lead melted from the heat of firing, combining with the copper in the bore, resulting in a brittle alloy that blew out of the barrel during each shot. Or at least that's the primary theory of how decoppering agents function. There may also be some melting of the copper--but the mail point is decoppering agents work, and have for a long time.
However, placing chunks of lead over the powder charge wasn't very practical with ammo fired in smaller rifles. Instead powder companies eventually started including particles of decoppering agents in the granules. Tin proved to have the same effect as lead, and by the 1920's some DuPont rifles powders included tin, denoted by "1/2" after the powder's name. Gun writers of the era sometimes noted that the tin often fouled the bores worse than copper jackets.
However, eventually both tin and bismuth proved to be the most practical decoppering agents, especially after lead became widely considered an environmental poison. (The problem with the early DuPont 1/2 powders wasn't the tin itself, but too much tin in the powder, resulting in the tin fouling.)
Decoppering agents were used in quite a few military powders by World War Two, especially the Ball powders developed by Olin in the 1930's. Ball powders were not only cheaper to make than extruded powders (in fact they could be made from recycled extruded powders) but speeded up production of military ammunition, since they flowed easily and accurately through mechanized powder measures.
Unfortunately, early Ball powders (or spherical powders, as they're generically called, since "Ball" was a trademarked by Olin) also left a lot of residue inside bores, due to the burn-resistant coatings that made slower-burning spherical powders possible. This fouling was relatively abrasive, so tended to rub more copper from bullet jackets, at least somewhat counteracting the decoppering agents.
Many recent powders, both spherical and extruded, tend to burn far cleaner, leaving far less abrasive powder fouling in the bore. As a result, decoppering agents are more effective. Today they're usually bismuth or a tin-bismuth combination, and work very well.
However, one problem that can still compromise their effectiveness is the ratio of decoppering agent to powder. Rifle cartridges vary considerably in their powder capacity to bore ratio, and bullets also vary considerably in how much they contact the bore. Then there's the jacket itself (or these days, the entire bullet), which can be anything from pure copper to pretty hard brass. As a result, while decoppering agents always reduce copper fouling, they may not totally eliminate it in some cartridge/bullet combinations.
Despite pretty long boattails, many of today's high-BC bullets have more contact with the bore, due to often being heavier in weight.
Plus, some barrels copper-foul more than others. I've owned factory rifles with barrels that became about copper-plated within 20 rounds, and other barrels (usually hand-lapped customs) that almost refused to copper-foul. Of course, there are also bore treatments to reduce copper fouling. Since around 2007, many shooters have used Dyna-Tek Bore Coat to fix (or at least tame) rifle barrels that tend to copper-foul.
But using powders with decoppering agents can work at least as well these days, partly because factory barrels have become smoother, even in some very inexpensive rifles. My most recent example is a new Mauser Model 18 in 7mm Remington Magnum, sent to me for magazine reviewing. The 18 is a sort of Euro-version of inexpensive American rifles, real-world retailing for around $500, though the injection-molded stock and easily adjustable trigger are superior to many other "affordable" rifles. Like other recent Mausers I've tested, the hammer-forged bore proved to be very smooth in my Gradient Lens Hawkeye Bore-Scope.
The Model 18 was fired 10 times during its first range-test, using inexpensive factory ammo to get zeroed, and check magazine feeding and other functions. Back home the Hawkeye revealed some copper fouling in the corners of the lands, but probably not enough to affect accuracy, so I didn't bother cleaning the barrel.
I then fired 90 more rounds during three range sessions without cleaning the bore, while trying various new bullets and powders. Three of the powders did not contain decoppering agents, so I alternated those rounds with others loaded with decoppering powders. In total, 14 of the 90 rounds were non-decoppering.
After a total of 105 rounds I used rubbing alcohol to remove the minimal amount of powder fouling from the barrel, then again checked the bore with the Hawkeye. The trace of copper fouling visible after the first 15 rounds was gone, despite around 20% of the rounds fired using non-decoppering powder. Essentially, it was a clean barrel.
I have seen the same sort of thing in several other new factory rifles during recent tests, including Franchi Momentums, Ruger Americans and Sauer 100s and 101s, all of which, like the new Mausers, also feature very smooth hammer-forged barrels. Much of the testing involved newer bullets with very high ballistic coefficients, which despite having long boattails still have plenty of contact with the bore due to their relatively heavy weights.
So do decoppering agents work? Yes, they do, but exactly how well they work in a particular barrels depends on several factors--and a bore-scope is pretty much essential in determining the outcome. You really cannot tell if a rifle's bore is cleaned of all copper by relying on anything else: I have used mine to examine many barrels that in theory should have been perfectly clean, due to a lack of "blue" on cotton patches used with ammonia-based solvents, and still found some copper, often quite a bit. The same has been true of any other cleaning product, whether abrasive, a "lifter," or another kind of copper solvent.
The other question, of course, is how much copper fouling reduces accuracy. Sometimes a moderate amount doesn't seem to hurt, but I have yet to encounter a rifle that really shot well with considerable copper in its bore. This is one reason I started keeping an accurate round-count, including cleaning intervals, on all my rifles many years ago. But in general most rifles, whether factory or custom, do shoot better when unfouled.
I've now had a Hawkeye for over 15 years, the last 2-3 with the latest model with upgraded optics. They're pretty expensive, but when I first purchased mine they were pretty much the only option--and contrary to what many shooters believe, they will not tell you much about whether a barrel will shoot well. Instead a scope is far more valuable in determining how well various cleaning products work, how well a chamber is cut, how much throat erosion is taking place, or how many "fire-lapping" bullets are required to smooth up a rough throat.
Today, however, there are far less expensive digital bore-scopes on the market. So far I haven't tried any that reveal the same level of detail as the Hawkeye, but any will show basic copper fouling.
What I do know is that anybody who dislikes spending time cleaning barrels, instead of shooting, will benefit from decoppering powders. That's exactly why I started experimenting with various techniques that reduce copper fouling many years ago, and why many of the rifle powders I use these days include decoppering agents. Most also tend to be temperature-resistant powders, which also helps in consistent results.
You may not "need" either for the shooting you do (and I certainly don't in some of my rifles, such as my traditional, iron-sighted lever-actions) but with so many 21st-century rifle powders featuring decoppering agents, its pretty easy to find one that works very well in any of today's super-accurate bolt actions, whether factory or custom.
The Mauser 18 shot VERY well with several loads using bullets from 120 to 195 grains, and by very well I do not mean MOA but much better. Which is one reason it's no longer one of the "loaner" test-rifles that regularly reside in one corner of my safe, but belongs to me.