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Rocky’s Reloading Room |
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Blue Dot in Rifle Loads
One of the most attractive aspects of the .22-caliber centerfires is their wonderful versatility. With the same .224 diameter bullets, different cartridges run the gamut from small game to 500-yard heavy varmints and even, where legal, some big game. This spread is achieved by selecting cartridges with more or less powder capacity, governed by case size. From the diminutive .22 Hornet to the booming .220 Swift, plus a pride of large and small wildcat cartridges, every imaginable niche is filled. But to cover both large and small ends of the niche, must we select different cartridges? Surprisingly, the answer is no!
There is another avenue. Downloading the large and medium cartridges will produce the same results as the smaller cartridges. Lower velocity is often accompanied by lower muzzle blast, reduced recoil, lessened reloading expense, and longer barrel life; but, thankfully, equal accuracy. The traditional way to accomplish reduced loads is to simply throw smaller powder charges using traditional powders for the cartridge. Useful to a point, this method can only be followed until chamber pressures decline to a level where combustion is no longer uniform.
Beyond that point, as powder charges are reduced, combustion becomes erratic and incomplete. Velocities vary widely, and so does accuracy. With powders appropriate for full charge loads, then, there is a floor below which load reduction is futile. But what about using non-traditional powders?
Before I say one word more, let me give credit where it is due. I would perhaps never have thought of this approach had it not been for James Calhoon, maker of those excellent and eponymously* named bullets. In an article published in the July 1999 issue (#31) of The Varmint Hunter Magazine, he discusses the basics of the method that follows. As they say, I owe all this to him.
If the object is to produce reduced velocity loads while still maintaining sufficient gas pressure to insure full combustion and repeatable accuracy, why not move to a powder with a faster burn rate? In his article, James suggested two: IMR 800X and Alliant Blue Dot. Although he had previously worked with 800X, James wrote that it had several drawbacks. Namely, it was difficult to dispense evenly and burned dirty. Nonetheless, he reported loads that ranged from .22 Long Rifle speeds all the way to near normal in the .223. But his latest shining star powder was Blue Dot, which took speeds far beyond the earlier experiments, burned very clean and flowed through a powder measure with ease. I was instantly intrigued.
Calhoon’s loads just might be the answer to a perplexing dilemma I had often faced. As a varmint hunter, I had often found myself either over- or under-gunned. I’d be shooting ground squirrels with a .22 Magnum, and a badger waddles through. Or I’d be coyote hunting with a .223 when I chance upon a tasty cottontail. In either case, the rifle in my hands would either be too weak for a humane shot or too powerful to preserve any edible meat. What’s more, it’s a situation that happens to us all. About the only thing I can count on some days is that I won’t have the right gun for the game that appears. A golf cart full of rifles is most definitely not the answer. But what if I had merely to switch ammo to answer the shot at hand? What if different loads could give me the equivalent of two or even three rifles? Townsend Whelen was right. No rifle is complete unless it has both full power and reduced loads worked up for it.
Enter the Blue Dot theory. Because it is rated as a medium-slow powder for pistols and shotguns, Blue Dot is specially formulated to meter well in small doses, ignite easily and burn completely in capacious cases with very high expansion ratios (translate that as big-bore, straight cases if you like). In a rifle case, with reduced charges, it bulks up fairly well, ignites without a burble and burns down to the last flake. In so doing, it produces a very sharp, fast pressure rise but considerably less gas volume than a charge of rifle powder. The result is a load that produces nearly normal pressures, but which burns all its powder very quickly. The pressure drops almost as rapidly as it rises, and the reduced gas volume can’t continue to accelerate the bullet down a long bore.
In effect, the bullet gets a very hard, but quick shove, then coasts out the barrel. With a heavy bullet, this could result in dangerous pressures and terrible ballistics, but with light bullets, the result is reduced velocity, much reduced muzzle blast and recoil, less barrel heat and erosion, and a heckuva neat solution to our “wrong gun” problem.
Enough theory; let’s get to some shooting! I started experimenting with the .223 for two reasons: it’s my favorite varmint round, and it’s the one for which James Calhoon developed data. I loaded up a batch of military brass with standard small rifle primers, backed off of the maximum 14.0 grain load in the article by a full grain and seated some 37 grain Calhoon hollowpoints. In short, the exact load listed in the article, but reduced by one grain or about seven percent. He reported 3,240 fps from a 24” barrel. My 21” Rem 788 tripped the Oehler 35 at 3017, while my 14” Contender managed 2950. Groups? I was astounded to measure consistent half-inch five-shot clusters at 100 yards from both guns.
This load therefore achieves almost the exact performance I get from a Hornet/K-Hornet/Bee rifle with the same bullet, with accuracy that’s measurably better. Drop the charge another grain, and the accuracy stays just under an inch while velocity drops down to 2800. Case expansion, which is a reasonably accurate way to monitor relative pressure, shows that these loads deliver from three-quarters to full load levels. The big difference is in muzzle blast and recoil. They shoot and sound like a Hornet.
In addition to their valuable role in rifles, these loads are perfect for all-round use in the Contender, or other short-barreled guns. The fact that they deliver nearly the same accuracy and velocity as full-power loads is great, but their reduced blast and recoil are the real benefits here. I love to varmint hunt with a Contender, but the muzzle blast from some cartridges, and with some powders, will peel paint. Trigger a normal rifle load of H335 in the .223 from a 14” Contender, and you’ll see - and feel - what I mean: a fireball the size of a hot air balloon and a blast like a Weatherby with a muzzle brake! It hurts!
So far, I’ve tried .223 loads with bullets in the 35 to 50 grain bracket. I see no reason to try heavier bullets. With reduced speeds, a heavier bullet may not be stabilized. Here are some .223 loads that I like:
35-37 gr bullets 13.0 Blue Dot 3000 fps 40-45 gr 12.0 2800 - 2700 50 gr 11.5 2500
Want to make your Hornet into a .22 Mag? Try these:
35 gr bullets 7.0 Blue Dot 2400 fps 45 gr 6.0 2100
As always, the usual reloading precautions apply. These loads are normal to warm in my guns, but should be worked up for your use. Use no more than 0.3 grain charge increases after backing down one full grain for start loads. Standard small rifle primers in all loads, although small pistol primers may also be tried. Good shooting!
Addendum:
I have received several email messages adding to the data about Blue Dot loads. In the .22-250, several readers have reported that a good load uses 45-grain Hornet bullets over 14.0 grains of Blue Dot. This yields 2600 fps.
If you perform some similar experiments, I would be happy to pass along your reports! Thanks!
Update 2007: In correspondence with another avid reloader and Blue Dot user, I’ve gotten the following rule of thumb. To determine the maximum charge of Blue Dot in most cartridges, simply fill a cartridge with Blue Dot, weight that amount and multiply it by 0.6. That means that 60% of a case-full is the approximate maximum charge. If you back off at least 10% more for a Start Load, you should be fine. Please understand that I have NOT tested this in very many cartridges, so you are strictly and completely on your own if you want to try Blue Dot in your custom .347 Magnosterone. |