DEVELOPING HORNET LOADS
.22 HORNET LOAD DEVELOPEMENT
By Bryan Armatys
Developing a load for the .22 Hornet is not much different than for any other cartridge---unless your time and patience are valuable to you. The Hornet is a very touchy cartridge, because of it's very small case capacity, and getting it to shoot those magical minute of angle groups can drive a reloader to the brink of insanity.
Many reloaders shoot the Hornet because of the challenge it presents, but in the end, they will have developed a Love/Hate relationship for the round. Here are a few tips (requirements) for getting this jewel to shine.
CASE PREP.
Clean all cases and trim to a uniform length. I trim my cases to 1.395" and tumble them for an hour. Same thing for new cases. Brand new brass can vary by as much as .005" in length. The idea here is to gain control of the only variable you can change: length.
With that done, check for uniform primer pockets and flash holes. Very few cases will fail this check, but check them nonetheless. Discard the ones that can't be fixed, or give them to the schmuk that just reloads for economy. Finally, separate cases by brand.
SEGREGATION.
Weigh at least 3 groups of 5 cases of each brand of case. The first group of 5 may weigh 262.1 grains, the second group 263.9 grains, and the third, 262.8 grains. From this we have determined that the average case weight is 52.6 grains for brand "A" cases. Do the same for brand "B" and "C" etc. Based on case weight average, choose the heaviest brand of cases to continue your load development. There are two reasons for this:
1. If, during load development, you exceed the pressure limits established for the Hornet, the heavier case will likely stand up to the excess pressure better than the lighter case.
2. A safe load in the heavy case will be safe in lighter cases you may want to try in the future.
This all boils down to case capacity (or the lack thereof). If the cases were properly prepped, they will be nearly identical in size and shape after being fired in the same chamber, but the weight of the individual cases will not change! So what's the difference?, you ask? Internal shape and size! Case head, web, and wall thickness variations between cases affect case capacity, and case capacity has everything to do with velocity and pressure.
The heavier case will reach peak pressure with a smaller powder charge than a lighter, larger capacity case. Therefore, a safe load in a small capacity case (higher case weight) can generally be considered safe in a case with slightly more capacity (lower case weight).
Now that we have selected the heavier brand of cases, let's segregate them a bit more. With a balance beam scale set to the average weight for brand "A" cases, I weigh the individual cases and separate them on a "way over, slightly over, slightly under and way under" average basis. You can develop a rhythm of doing this that does not require the beam of the scale to come to a complete stop for each case. Now, again, select the heaviest group of cases. You can continue this process as long as you like....the time is yours, ya know. In the end, you will have assembled a group of cases that are very nearly the same size, shape, and weight--hence, the same internal capacity. Now it's time to start working with things that can be changed.
BULLET SELECTION.
Simple enough. Select a bullet designed for your application. Rapid expansion is not really necessary for target work, and full metal jacket bullets are rarely recommended for hunting prairie dogs. Check out several bullet manufacturer's recommendations, then consult the exterior ballistics tables for the flattest shooting bullet available in your chosen style. The one with the highest ballistic coefficient is the one you want.
POWDER SELECTION.
Select a powder from the manufacturer's data that will propel your chosen bullet at a velocity suited to the intended use, preferrably one that hits that velocity with less than a maximum recommended load.
PRIMER SELECTION.
Pick one. At this time primer selection is not important...you can change primer brands later and see if the load shows improvement.
NOTE: There has been some discussion surrounding the use of small pistol primers in the .22 Hornet. Supposedly, they enhance load uniformity and therefore accuracy. Keep in mind the fact that pistol primers have thinner, softer cups and may puncture at Hornet pressures. If you elect to use small pistol primers, watch closely for signs of primer failure.!!!!!
PUTTING IT ALL TOGETHER.
Neck size your cases only to the point on the neck where the base of the bullet will be when seated to the proper depth. This is determined by several factors. If the firearm is to be used with a magazine, the OAL of the cartridge should be set to SAAMI standards.
Single shot rifles and pistols can use overall lengths up to 1/32" short of touching the rifling. On these, choose a length between that maximum for your firearm, and standard OAL. Again, this can be changed later to determine the impact on accuracy.
NOTE. The Hornet case is very thin and fragile. Neck sizing without proper lubrication of the inside and outside of the neck can cause the case to collapse slightly in the web area. You may not notice the slight extra pressure needed to close the bolt on the rifle, but the extra width of the case will cause difficult extraction that can be misread as excessive pressure. If you are serious about load development and safety, check your sized cases in the chamber of the firearm. If a freshly neck sized case does not easily chamber and extract from the firearm it was previously fired in, SOMETHING IS WRONG!
Seat the primer selected above to a uniform depth, and carefully weigh out a powder charge that is at least 10% less than the maximum recommended, or 10% less than the charge specified for the velocity you are looking for. I normally load 10 rounds at this level, and 10 more at .1 grain more, and head to the range. If the second load is more accurate and has more consistent velocity, and there are no signs of excessive pressure, I will load 10 more at .1 grain over the second load and another 10 at .1 grain higher again. This is done till I see signs of pressure or arrive at the maximum recommended load-whichever comes first. Then analyze the groups and the chronograph data. If a particular charge is more consistent and accurate, I home in on it, concentrating on internal ballistics. I'll back the charge down a bit and substitute a different brand of primer, and work back up to the best load specs. After doing this with several different primers, I select the best performing one and move on to bullet seating depth. Normally, I start with a short OAL on the above testing and after finding the best primer, I start to seat the bullet out .010" at a time till I find the most accurate combination. By now, I have found that with case "A", primer "B", and charge weight "C", my chosen powder and bullet can be expected to shoot groups of size"X", when loaded to an OAL of "Y".
Is it good enough? If it is, congratulations on a job well done. If not, move on to the external ballistics end of things and try your second choice bullet, leaving primer and powder choices the same. Again, start with a conservative charge and work up. Then start changing seating depth again. If the second choice bullet produced better accuracy than the first, good--that is real progress. If the accuracy fell off, we have some hard decisions to make. Was the first bullet load really bad enough to warrant continuing this process, or is it really a load that satisfies the original intent? The next step in this process is to start all over again with the original primer, the original bullet, and a new powder.
Are you beginning to hate the Hornet? That small capacity case just magnifies the effect of changing primers, powder charges and bullet seating depths. I love the Hornet because I love to "tinker" with things. I love the challenge. If I didn't, I wouldn't own one.
Bryan Armatys
Last Modified: January 3, 2012