CAPACITY OF FIRED 45-GRAIN CASE IN YOUR CHAMBER CASE FILLING RATIO
GRAINS
WATER <60% 14.7
14.8 14.9 15.0 15.1 15.2
-0.10|-12 -0.05| -5 0
+0.05| +5 +0.10|+12 +0.15|+17
CHARGE CORRECTION (GR.) | VELOCITY CHANGE (FPS) 60%-80%
-0.14|-14 -0.07| -6 0
+0.07| +6 +0.14|+14 +0.21|+20
a case holding more than 14.9-grains, increase charge, to get equivalent pres- sure (but more velocity). Loading Techniques and TooLs Forster, Hornady, Lee, RCBS, and
Redding offer Hornet dies. For these tests, I primarily used the following: Lee Collet Neck Sizing die RCBS Gold Medal Seating die These tools proved most useful
as well: Forster Benchrest Full-Length
Sizing Die RCBS APS Priming Tool, press
mounted Redding UltraMag Press RCBS Charge Master Electronic Measure and Scale Hornady Powder Measure RCBS 17-caliber funnel Generally, neck sizing is adequate
for Hornet reloading. Maintaining easy chambering and extraction did not re- quire full-length resizing of cases used in this study, despite repeated reloading and my use of some loads that gener- ated excessive pressure. However, some guns and action types might not be so forgiving. If I ever needed to full-length resize a Hornet case (as when using cases that had been previously fired in a different gun), I would use a full-length neck-bushing sizing die with the thick- est Redding Competition Shellholder that would result in free chambering of the sized case. Alternatively, I would use the excellent Forster Hornet Bench- rest die (the raised expander is a plus) adjusted to size the case only enough to assure free chambering. The latter was precisely the meth-
od I used with cases that I had fired in the Savage before using those in the CZ. The base of the Savage chamber is just slightly larger than the base of the CZ chamber. So, without a bit of resizing, reusing cases in the CZ that I had first
Page 168 Winter 2012
80%-100% -0.18|-15
-0.09| -7 0
+0.09| +7 +0.18|+15 +0.27|+22
>100% -0.20|-16
-0.11| -8 0
+0.11| +8 +0.20|+16 +0.31|+24
fired in the Savage required significant bolt closing effort. I sized and polished the mandrel
in the Lee collet die to 0.222-inch. This increased bullet pull, which usually improves accuracy potential. With proper technique, all tested
propellants meter easily and accurately from any quality measure. I charged each case using a funnel and a technique that engenders a swirl as the charge passes through the funnel because this improves density and granule-packing scheme uniformity within each case and from one case to another and it, therefore, improves ballistic uniformity and accuracy. swirL charging
The goal with this technique is to
deliberately create a swirl within the granule stream as that passes down the funnel, toward the discharge. To do so, locate the pour spout of the pan against the side of the funnel (near the top), with the spout pointing at a 90-degree angle to the funnel discharge. Then pour the charge slowly. Compared to just pouring the charge normally down the middle of the funnel, this technique always improves charge density — typi- cally about 5% with tubular propellants and up to about 8% with some ball-type propellants (actual values depend upon granule shape, case diameter and shape, handloader skill, and funnel and pan being used).
Improved uniformity of granule-
packing scheme is significantly ben- eficial, whether charge is compressed or loose under the bullet. Even with a loose charge, resulting packing scheme uniformity is surprisingly resistant to vagaries of handling, storage, and trans- portation. Actually, short of high-energy vibrations, it is essentially immune. As noted, swirl charging usually improves ballistic uniformity and accuracy. (I
must say “usually,” because in 25 years, during which I have tested hundreds of loads, I have found a single exception but that might have been a fluke.) I have created swirl-charging fun-
nels to use when pouring charges from a pan and when dumping charges from a measure (the latter screws into the measure discharge). If you do not swirl charge or otherwise settle the charge, it is unlikely that you will be able to use many of the listed maximum loads that I suggest here. Specific feasible charge density
with standard pouring and swirl-charge pouring depends upon several factors. First, size and shape of case: Depend- ing upon the relationship between the size and shape of individual granules and diameter of case interior along case length, resulting charge density of any given propellant can vary by sev- eral percentage points. Second, funnel shape: How steep the cone is, diameter of discharge orifice, smoothness of tran- sition from cone to discharge orifice, surface smoothness, etc. Third, specific shape and length of pan pour spout. For data listed here, I used the
RCBS 17-caliber funnel and the pan from the RCBS Charge Master scale. Other funnels and pans will give dif- ferent results.
PercenT FiLL Any charge near a 100-percent
filling ratio is likely to be inaccurate. De- cades ago, the late Mr. Delaney, working as chief ballistician at Hercules, recog- nized this problem. Any such load is apt to create cartridges of two basic types: first, those where the charge settles a bit more than average and where the charge is therefore uncompressed after bullet seating; second, those where the charge settles a bit less than average and where the charge is therefore compressed dur- ing bullet seating. Cartridges from such loads are well-known for shooting into separate groups. This is another proof of just how accuracy-critical consistent granule packing is within the charge in each cartridge and among the charges within a group of cartridges. Depending upon how you charge
the case it is possible that your charge could fall close to a filling ratio of 100 percent. Bulk density of some propel- lants can vary by several percent, due to normal lot-to-lot variation. When this situation exists or seems likely to
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