BruceB
08-18-2006, 04:34 PM
Anyone with a chronograph knows that velocities in loading manuals are more "indications" of what we MIGHT expect, rather than cast-in-stone bedrock figures.
I've been using personal chronographs intensively since 1970, and I know this to be a true statement. However, I DO expect a reasonably-close correlation between "theirs" and "mine" when shooting one of their recipes.
Last week, I took some .45-70 loads to the range for testing in my 30" Shiloh, among which were a series based on 2-grain increments of RE-7 powder. The series, using the 429-grain SAECO #021, started at 40.0 grains and went through 42.0, 44.0, 46.0, and 48.0 grains, ten rounds at each charge weight.
Lyman's handbook also started at 40.0/RE-7, and quoted a speed of 1493 fps from either a 24" UR or 26" Winchester barrel. I pretty much know how this Sharps feels with various levels of loads, and when the first round of 40.0 grains went off, my mind said "Holy Sheep!" (or words to that effect). A peek at the chrono showed a speed of exactly 1700 fps, or 207 fps above the Lyman velocity. I fired four more rounds, and the average for the five was 1691 fps.
Also, it was very uncomfortable. With the rifle set up with a long-range vernier Axtell sight, there's no way to get one's thumb safely over the stock to help control the recoil, and likewise with the minimal fore-end nestled into the rest, there's not much to hang onto out front, either.
I immediately decided to abandon the entire series of loads, except for a single five-shot "curiosity" string with the 46.0 load. My rifle turned in 1869 fps average, with extreme spread of just 11 fps. For this same 46.0/RE-7 load, Lyman used a 28" barrel in their Universal Receiver ("Ruger chamber") and reported 1687 fps.
There's NO way that just two extra inches on my Sharps' is gonna generate almost 200 fps extra speed!
Pressures were perfectly safe, but I think this is one more valid reason for owning a chronograph. The particular differences in this instance are among the most extreme variances I've ever seen in my personal experience with Manual-derived loadings.
I've been using personal chronographs intensively since 1970, and I know this to be a true statement. However, I DO expect a reasonably-close correlation between "theirs" and "mine" when shooting one of their recipes.
Last week, I took some .45-70 loads to the range for testing in my 30" Shiloh, among which were a series based on 2-grain increments of RE-7 powder. The series, using the 429-grain SAECO #021, started at 40.0 grains and went through 42.0, 44.0, 46.0, and 48.0 grains, ten rounds at each charge weight.
Lyman's handbook also started at 40.0/RE-7, and quoted a speed of 1493 fps from either a 24" UR or 26" Winchester barrel. I pretty much know how this Sharps feels with various levels of loads, and when the first round of 40.0 grains went off, my mind said "Holy Sheep!" (or words to that effect). A peek at the chrono showed a speed of exactly 1700 fps, or 207 fps above the Lyman velocity. I fired four more rounds, and the average for the five was 1691 fps.
Also, it was very uncomfortable. With the rifle set up with a long-range vernier Axtell sight, there's no way to get one's thumb safely over the stock to help control the recoil, and likewise with the minimal fore-end nestled into the rest, there's not much to hang onto out front, either.
I immediately decided to abandon the entire series of loads, except for a single five-shot "curiosity" string with the 46.0 load. My rifle turned in 1869 fps average, with extreme spread of just 11 fps. For this same 46.0/RE-7 load, Lyman used a 28" barrel in their Universal Receiver ("Ruger chamber") and reported 1687 fps.
There's NO way that just two extra inches on my Sharps' is gonna generate almost 200 fps extra speed!
Pressures were perfectly safe, but I think this is one more valid reason for owning a chronograph. The particular differences in this instance are among the most extreme variances I've ever seen in my personal experience with Manual-derived loadings.