OAL
Variation (inch)
+0.20 +0.15 +0.10 +0.05 0.0
-0.05 -0.10 -0.15 -0.20
Approximate Charge Adjustments OAL COMPARED TO TESTED LOADS Loads at Equal Chamber Pressure
Charge Correction (gr.) | Velocity Change <60% 60%-80% 80%-100% >100%
+0.45 | +76 +0.60 | +91 +0.96 | +106 +1.06 | +115 +0.34 | +58 +0.45 | +69 +0.70 | +80 +0.80 | +86 +0.22 | +40 +0.31 | +47 +0.45 | +54 +0.53 | +58 +0.12 | +22 +0.15 | +25 +0.22 | +28 +0.26 | +29 0
0
-0.12 | -22 -0.22 | -40 -0.34 | -58 -0.45 | -76
-0.15 | -25 -0.31 | -47 -0.45 | -69 -0.60 | -91
Seating Depth Study
Barnes 30-grain Varmint Grenade properly plated with molybdenum-disulfide, seated for various amounts of bullet-to-rifling jump in Remington cases, Alliant Power Pro 300-MP @ 15.6-grains, Federal 100 Primer. Average accuracy at 100 yards for several five-shot groups with each combination. I tested these loads in the CZ.
VARIATIONS IN SEATING DEPTH STUDY Approximate MV Std. Accuracy
BULLET
30-GRAIN VARMINT
Jump -0.005
GRENADE +0.005 (MOLY- PLATED)
+0.000 +0.010
+0.015 fps
3,583 3,580 3,544 3,530 3,582
Dev. (8-shots)(inch) Comments 12
19 28 20 37
0.70 1.65 1.75 1.70 2.25
6 in one hole 7 near 1 inch 5 inside ¾ inch 5 inside ¾ inch 5 inside 1 inch
Point of test: To demonstrate that seating depth matters, which would seem evi- dent, even to a casual observer. Further tinkering with these components might produce better results. No doubt, other primer and propellant combinations with various other bullets would show variations, similar or otherwise.
Moly-Plated versus Naked Bullets
All reported tests represent results
using properly moly-plated bullets. When considering such a tiny cartridge, many handloaders will consider this ex- tra effort to be wasted; however, my ex- perience proves that moly-plated bullets always offer a velocity advantage and a fouling reduction. When varminting, I routinely shoot 300, high-performance loads from my 22-250 or my 5/35 SMc without cleaning and without seeing any indication of accuracy loss. I have fired more than 750 rounds from my (ceramic treated) 17 Ackley Hornet without cleaning and without any accu- racy loss (subsequent cleaning required exactly three soakings with Sharp Shoot R Wipe Out). Is moly worth the effort? It certainly is to me. If you choose to use naked bullets
in your Hornet loads, likely you will find that your maximum loads will be about 0.4 grain less than those listed
Page 164 Winter 2012
here and likely you will see about 25 fps less velocity. Greater differences would not surprise me. However, moly significantly de-
creases bullet pull and limited bullet pull and the resulting premature bullet movement that commonly occurs when the primer blast hits the bullet base de- stroys accuracy and ballistic uniformity. It is likely that the use of naked bullets will make it far easier to find best ac- curacy in the Hornet. Because I hate to clean barrels, I will never know. Bullet seatiNgdePth
I set overall length (OAL) of most
tested loads to give 20/1000-inch bullet- to-rifling jump. All tested loads had enough shank seating depth to assure reasonable robustness but many of those had less than two-thirds caliber (0.149- inch) of bullet shank seated in the case mouth (my preferred minimum seat- ing depth). Your gun is apt to require a shorter OAL to maintain 0.020-inch bullet-to-rifling jump (will increase
0
-0.22 | -28 -0.45 | -54 -0.70 | -80 -0.96 | -106
0
-0.26 | -29 -0.53 | -58 -0.80 | -86 -1.06 | -115
pressure) or will give less jump with the listed load (is apt to increase pressure). Note that if you are loading for a
magazine-fed gun and you prefer to use the magazine, you might have to load your cartridges at a significantly shorter OAL. In that situation, a charge reduc- tion will be needed. The accompanying table suggests approximate charge cor- rections associated with OAL changes. Evidently, this combination works
best with the bullet driven at least slight- ly into the rifling (extracting samples of this load at the longest tested length demonstrated that no tendency existed for the bullet to hang in the rifling). Loading this bullet to a bit longer overall length might result in even better accu- racy. However, the potential for sticking a bullet in the leade would make such a load less desirable for field use. Obviously, 300-MP offers sig-
nificant Hornet velocity, and pressure of these loads was very mild. While I can only guess at actual pressure generated by this load, the tested (pistol) primer showed no hint of flattening. I have seen factory-load Hornet primers showing more evidence of pressure. Because those are rifle primers, likely, pressure generated by this load was similar to, or less than, pressure generated by some standard Hornet factory loads. ProPellaNts tested
In previous K-Hornet testing, I
included almost every propellant that might feasibly produce good velocity along with several popular choices that are not as efficient. That experience suggests to me that readers who are interested in maximum Hornet accuracy and velocity will be best served with the following propellants: 300-MP A1680 H110 Lil’ Gun IMR 4227 2400
Interestingly, but not necessarily
surprisingly, every one of these propel- lants requires a near case-full charge to generate maximum performance. This is one more very good reason to improve the Hornet! In the K-Hornet study, none of the faster propellants that will generate normal pressures without significant charge compression showed enough accuracy or velocity potential to interest me in testing those here. In all
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