change to better accommodate them. The same is true with twist rates which, in some cases, have not been changed to properly stabilize today’s bullets. For example, 22 Hornets should no longer be made with twist rates of 1 turn in 16 inches. One turn in 14 inches, maybe in 13 inches, would be far better. Twist rates become even more important as we move to “GREEN” bullets (bullets without any lead). While on my soap box, I wonder
why American manufacturers don’t, or can’t, make better 22 Hornet cases. As covered earlier, rim thickness has tremendous variations. Is it economics or attitude? I probably will try some foreign-made cases if I ever need to purchase any more. SAD, SAD, SAD! Part of the above deviation ex-
Case shows no indication of any Case Head Separation after two shots with a 0.055 rim and four shots with a 0.058 rim. (Cases had been loaded and fi red four times prior to this evaluation. See Table 1.)
fi rm contact with the case neck is highly debatable. I started to include in this article an in-depth study along with my opinions on this subject, but decided it should be a stand alone article. With regard to opinions, I need to caution you that they are like belly buttons – everyone has one. When talking about bearing sur-
face and full diameter lengths, seating depth must be discussed. Seating Depth (SD) is typically defi ned as “the length of the bullet below the case mouth” or “the distance the bullet is seated in the case.” These defi nitions are adequate assuming you are concerned with the bullet occupying powder space or with the overall length of the loaded cartridge but are of no value if you are concerned with aligning the bullet with the case and/or securely holding it in place. To eliminate this problem I suggest we need two terms with corresponding defi nitions as follows: (1) Total Seating Depth (TSD). The
distance the base of the bullet is below the mouth of the case. (2) Effective Seating Depth (ESD).
The length of the bullet which is in fi rm contact with the inside of the case neck. A review of bullets on hand shows
the difference between TSD and ESD approaches 0.15 inch. It is 0.061 inch for the 40-grain V-Max as loaded in my prepped Hornet cases. The accuracy
Page 136 Spring 2012
load noted earlier has a TSD of 0.183 inch and an ESD of 0.122 inch at a DOL of 0.060 inch. At a DOL of 0.020 inch, which gives the best accuracy in the Hornet being used, the TSD is 0.143 inch (0.183 minus 0.040 and the ESD is 0.082 inch (0.122 minus 0.040). I consider an ESD of 0.122 inch adequate for the intended use of these cartridges but do not consider an ESD of 0.082 inch as adequate. The difference in accuracy with
this rifl e, fi ve shots at 100 yards, for a DOL of 0.020 vs. a DOL of 0.060 inch is slightly less than 0.10 inch. It, like most other rifl es, has more than one sweet spot as determined by shooting numer- ous groups at different DOLs. I suspect it has another sweet
spot at a DOL of something like 0.100 inch and I may have to fi nd out after an additional 0.030 inch of throat erosion occurs. The good news is that it will take approximately 4,300 additional shots for this amount of erosion. The bad news is a sweet spot at a DOL of +/- 0.100 inch probably won’t be quite as sweet as those at 0.020 and 0.060 inch. For what it’s worth, I would like
to see rifl e/barrel manufacturers reduce leade lengths in their products, primar- ily the smaller calibers in which we shoot light bullets with the highest BCs we can fi nd. Bullet shapes have changed in recent years and rifl e barrels need to
plains the 0.060 DOL, part of it covers the need for new terms and their defi ni- tions, and part of it allowed me to get on my soap box. I hope it didn’t bore you too much, I hope you agree with most of it, and I hope it gave you something to think about. Back to the rim thickness evalu-
ation – or just about back. Important things fi rst so you need to check your now warm/empty one and decide if it should be replaced with a cold/full one. OK, now back. Summarizing, I
have an action plan. Cases with three different rim thicknesses have been se- lected, and the accuracy load has been selected. I have carefully loaded the 33 selected cases which have a maximum bullet run-out of 0.003 inch with the vast majority being between 0.000 and 0.002 inch. I am now in a holding pattern waiting for a suitable day to shoot the fi rst 33 rounds. LATE FEBRUARY 2011
I have been in a holding pattern
for some two weeks during which the weather has not been conducive to shooting good groups. I decided to have another deviation and relate a couple of events which you may fi nd entertaining. I love to deer hunt and have done
more than my share of it during the last 25 years. I was a member of the same club for 20 of these 25 years. Members of this club could invite a guest fi ve times a year for evening hunts and most did. One member invited a guest whom I will call Roy. Roy was a friendly, lik- able person who had previously been deer hunting only two or three times.
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