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Developing Pet Loads

Developing Pet Loads

Finding the bullet/powder combos your rifle likes is not as difficult as you might think.

By John Haviland

When a new rifle comes out of its box all bright and shiny, your first thought is to shoot it. Go ahead and scratch that itch. But your next move should be to develop loads tailored to the rifle that deliver its best accuracy and hunting potential.

The first step in selecting pet loads is to decide how the rifle will be used. A rifle chambered for a large magnum cartridge will probably fire a full-power hunting load. These cavernous cases can make reduced-velocity practice loads difficult to assemble. However, cartridges like the .270 Win, .30-06 Spfld and the new 25 WSSM are very versatile and can be loaded right up to the maximum for big game hunting, short-range small game or accurate target practice.

My newest rifle is a Cooper Model 22 chambered in .22-250 Rem. The rifle weighs 10 pounds with a Nikon 4-12x scope, so it will be primarily used from a rest for informal target shooting and short- and long-range shooting at ground squirrels and prairie dogs. For the Cooper to shoot its best at those targets requires the best possible accuracy in both maximum and reduced-velocity loads.

A tiring and expensive method of developing those loads would be to shoot every possible combination of powder and bullet that's suitable. With this approach, though, some magnum cartridges might wear out
the barrel bore before the right loads are found.

Bullets

Developing Pet LoadsHowever, there's a shortcut. That work has already been done, and the results are readily available in reloading manuals. Not only that, bullet companies like Sierra devote sections of their reloading manuals to the best uses for each of their bullets and the cartridges that shoot them best.

I decided on a 55-grain bullet as a maximum-range varmint load for the Cooper .22-250. This weight bullet with a plastic tip, such as the Hornady V-Max, Nosler Ballistic Tip and Sierra BlitzKing, retains velocity well and readily expands at long range. All three brands of these bullets are very accurate and would make a good target load, too. I chose the Nosler 55-grain Ballistic Tip.

For a reduced-velocity load, I wanted to duplicate the velocity of the .221 Fireball and .22 Hornet. At this slower speed, a lighter-weight bullet would still upset on prairie dogs at 200 yards or so. I picked the Nosler 40-grain Ballistic Tip for this load.

Powders

Developing Pet LoadsReloading manuals also include loading tips and suggestions for the best powders for each cartridge. Every loading manual I consulted recommended Hodgdon Varget as an excellent powder for the .22-250. Additional suggestions included Reloder 15, IMR-4895, N140, TAC, IMR-4064 and Benchmark.

While powders within a certain burning rate work well in a cartridge, there is really no magical "best" powder to use. No powder will improve the inaccuracy caused by an improperly bedded receiver and barrel or a rough and heavily fouled bore. About any suitable powder should shoot fairly well in a properly tuned rifle.

Further refining the selection of powders requires making sure a powder nearly fills the case and delivers the intended bullet velocity. A full case keeps the powder tight against the primer flash hole and contains no air pockets. That contributes to consistent velocities. A powder charge that only partially fills a case, though, settles every which way and can lead to an inconsistent powder burn and wide swings in velocity.

When choosing a powder, also consider that cases that aren't full to overflowing with powder are also easier to handle. For example, maximum amounts of powders like Varget and Benchmark fill a .223 Rem case right up to the top of the mouth. Some loads even require repeatedly tapping a case to settle the powder so a full load fits in it. Often while these cases are handled or the cases rotate to the next station on a progressive press, some of the powder spills.

A powder that measures precisely through a powder measure can also save hours at the loading bench. If you're going to load several thousand cartridges for a summer campaign in the prairie dog towns, weighing each powder charge would take a month of Sundays. Ball powders like Ramshot TAC or extruded powders with small granules, like Hodgdon Benchmark, measure precisely through a powder measure and can be dispensed right into the case.

Subscribe Today!I picked six powders to load with the Nosler 55-grain bullet. The first charge weights were about 2 grains less than the maximum stated in several reloading manuals. Those were fired to make sure they developed no indications of excessive pressure and grouped fairly well. The second batch of reloads was increased by about 1 to 2 grains of powder, which were the peak loads listed in the manuals.

These maximum loads were scrutinized for signs of excessive pressure. The slightest resistance of opening the bolt, cratering of the firing pin dent on primers and flattening of primers are all signs of too much pressure. Then again, a load may develop excessive pressure and show no signs of it. That is, until a case splits or powder gas blows through a primer pocket. That's why it's smart to never exceed the pressure tested loads listed in reloading manual.

All of the maximum loads shot fine through the Cooper rifle. I fired a three-shot group with each load. A three-shot group is not the best indication of a load's accuracy, but it can be a sign of inaccuracy. If a load tends to string or throw three bullets here and there on a target, it's a pretty sure bet two more or five more bullets will fly just as wild.

Records and Shooting Conditions

Every step of the way, I kept records. Without them, all the work of preparing loads and shooting would have been wasted. Without complete records, assembling the same load again or troubleshooting a good load that has gone sour is impossible.

When I first bought a chronograph, I haphazardly wrote down bullet and powder weights and average velocities. Looking back at the incomplete data, I realized I needed a host of other information, like the exact gun the loads were fired from, case and primer brands, overall loaded cartridge length and group size. Comments such as a gun's trigger-pull weight, how often a barrel required cleaning to maintain its accuracy and shooting conditions would have also been helpful. Write down everything. You never can tell when the information will come in handy down the line.

While shooting the Cooper .22-250, accuracy started to fall off slightly after firing 20 or so rounds. A few solvent-soaked patches pushed through the bore, 20 strokes with a brush followed by a couple of wet, then dry patches returned the accuracy. That was noted in my records.

Good shooting conditions are essential when developing pet loads. Winds of varying speed and directions can throw bullets all over the place. Strong winds can also buffet a rifle and shooter and ruin any hope of accuracy in a target rifle. One November, I shot a dozen loads through a Ruger MKII all-weather bolt-action rifle during a blizzard. The rifle shot all the loads into about 1.5 inches at 100 yards. The rifle's accuracy didn't receive a fair shake because of the nasty weather. But then again, that's exactly the type of conditions in which the rifle would be used.

Developing Pet LoadsThe wind was calm on the days I shot the Cooper rifle. Not even the peach fuzz in my ears moved. Following is what the various loads from the Cooper Model 22 .22-250 wearing a Nikon 4-12x scope set on 12x delivered for average velocity 5 feet from the muzzle and group size at 100 yards (see chart).

The Cooper rifle presented the pleasant problem of having to pick a couple loads from all these great groups. The TAC/32.8 load was the pick for a target load. Its group was triangle-shaped, which indicated my shooting ability (or lack of it) caused what little spread there was. Then again, the Benchmark/33.5 group was not all that much larger than the TAC load. The Benchmark's standard deviation of 14 also indicates the load was very constant.

The Benchmark maximum powder load is the long-range varmint load. It developed 100 feet per second higher bullet speed than any other load, and its accuracy was within a hair's width of the best. Plus, Benchmark's fine kernel size produces consistent charge weights when dispensed through a powder measure.

All that remained was to load TAC and Benchmark again and fire two or three five-shot groups to confirm the initial results.

Reduced Loads

All the sizzle of a maximum load from a .22-250 is pretty much wasted when ranges are short. Reducing the velocity of the .22-250 to the mild level of the .22 Hornet or .221 Fireball saves powder, recoil and muzzle blast. Correctly loaded, these reduced-velocity rounds are just as accurate as full-power loads.

Reducing the charge of relatively slow-burning powders like H4350, H4831 and Reloder 22 much below 10 percent of maximum can lead to a dangerous rise in pressure. Ron Reiber, a ballistician for Hodgdon Powder, said this rise in pressure occurs in cartridges with a large powder capacity compared to their bore diameter, like the .243 Win, .25-06 Rem and small-bore magnum cartridges.

"What happens is the reduced amount of powder leaves a lot of air space in the big case and the powder doesn't ignite properly," Reiber said. "Some of the powder will ignite first and break down, and then the flame will jump across the air space and finally ignite the rest of the powder." The pressure from the powder that has burned first moves the bullet into the throat of the barrel. When the rest of the powder burns, the bullet stuck in the throat has no running start to even out the rising pressure. That causes a sharp increase in pressure.

"I've never been able to reproduce this condition in the lab with a rifle with a new barrel," Reiber noted. "But I have been able to do it with a barrel chambered for an overbore cartridge that has a rough throat, like say a .243 Winchester that has been fired 500 times. You need both the reduced amount of slow-burning powder and a rough bore to make it happen. And that combination can raise pressure so high, it will lock a rifle bolt shut."

Reiber said he has never had much luck with reduced loads in small-bore magnum cartridges. "Say you're shooting a 140-grain bullet at 3,200 feet per second from a 7mm magnum. You can switch to H4895 powder to reduce velocity to 2,600 fps, and that will work okay because the powder still takes up about 60 percent of the powder space. But to reduce the velocity of magnum cartridges slower than that, down to say 2,000 fps, it's difficult to get uniform velocities."

Generally speaking, with standard-size cartridges like the .30-06 on down to the .223 Rem, the slower the velocity desired, the faster-burning powder the handloader should select. For example, the .25-06 Rem accurately shoots full-power big game loads with 120-grain bullets and slow-burning H4831 or H1000 powders. For practice and small game shooting out to 250 yards, the 85-grain Nosler Ballistic Tip and H4985 shoots accurately at a reduced-velocity of 2,900 fps. Even faster-burning H4198 shoots the Speer 87-grain bullet well at 2,600 fps. And way down at 2,100 fps, even faster-burning H4227 accurately shoots the Speer 87-grain bullet. That's because each of these powders delivers its best ballistic performance within a certain pressure range. The faster a powder's burning rate, the lower the pressure range at which it works best. 

Developing Pet LoadsFor the .22-250's reduced-velocity loads with the Nosler 40-grain Ballistic Tip, I chose three powders and received the following results (see chart).

The widest spread in velocity was 65 fps with IMR4895 powder. Both of the H4198 loads had spreads of about 50 fps and shot very well. Even 748 powder shot fairly well, producing velocity similar to a .22 Winchester Rimfire Magnum. The H4198/23.0 looks like the choice, though, for accuracy and right level of velocity.

My time was well spent at my loading bench and at the shooting-range bench developing pet loads for my Cooper .22-250. With these loads, the Cooper and I are going to have a lot of fun together for a long time.

Reprinted from the November 2005 issue of Buckmasters GunHunter Magazine. Subscribe today to have GunHunter delivered to your home.

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