The boys were out playing today. Central CA AM weather was damp, foggy and moderately cool until the fog lifted at about 10:30 AM. We shot a 500-meter pistol silhouette match, a club match, in the morning. After the fun and festivities RickE, my shoot’en pard, and I got down to some bullet testing with our 45-90’s. Rick has a very nice 45-90 Shiloh Sharps with a 30” octagonal barrel. Mine is a Pedersoli John Bodine 45-90, 30” barrel and DST’s. Both rifles are very accurate and well made.
Conditions were excellent for accuracy testing at 500 meters. The cloud ceiling was at about 1,000 ft with flat light and little wind. The sights and targets seem to be most visible under these conditions. The wind was mild from about 1 mph up to a max of 5 mph generally from about 9 O’clock. It just does not get any better than these types of conditions for shooting BPCR’s with iron sights.
The focus of today’s testing was to add to our growing body of knowledge and experimental results concerning how bullet design affects elevation and windage correction requirements. We shot 3 different bullets with the same 85.0-grain load of Swiss 1.5 in both rifles.
The three bullets tested were all cast in 20-1 alloy. They were:
Lyman Postell, 530 grains
Paul Jones Creedmoor, 545 grains
Theodore/Brooks Grooveless 3G, 555 grains.
Paul Jones Creedmoor – Lyman Postell – Theodore/Brooks 3G Grooveless
The Theodore/Brooks bullet dimensions are:
My load for the Lyman Postell and Theodore/Brooks Grooveless was:
Rick’s loads were the same except he did not use over-primer-wads.
I started the testing with Rick spotting. All shooting was done off the sticks. The first load shot was the Lyman Postell. After about 6 rounds to get zeroed with the Postell the 3G grooveless bullet was shot. This bullet weighs about 25 grains more, was going about 25 fps slower but still required about 3 MOA less elevation than the Lyman Postell. The barrel was wiped between shots for both the Lyman Postell and Theodore/Brooks 3G grooveless bullets. Once the 3G load was centered up a 4-shot group was shot that could have been covered with the palm of my hand. The 3G is one heck of an accurate bullet. The 10-shot, 100-yard paper group posted several days ago certainly portended the accuracy at 500-meters. I was going to shoot more, but to be honest the load shot so well I did not want to waste any more ammo as I’d like to head down to Coalinga next week and shoot it at 1,000 yards against the hopped-up, large capacity, fast-twist 38’s.
Rick and I traded places with him on the
sticks with his Shiloh Sharps and me on the Kiowa. First Rick shot the 545
Paul Jones Creedmoor to get his sight settings. I brought 10 Theodore/Brooks
3G grooveless bullets that had already been coated with White Lightening BPCR
Dipping Lube. I grabbed some of Rick’s ammo, pulled the PJ’s and slipped in
the 3G’s. With his PJ sight settings Rick’s first 3G grooveless bullet impacted
the berm about 3 MOA over the back of the ram. He had to come down 4 MOA to
hit center. He then shot a 7-shot group that had about 1/2 MOA of vertical
and about 1.5 MOA of horizontal. The wind was picking up and letting off from
about 2 to 5 mph. We did not adjust for windage.
Instead we were interested in observing the wind affects on trajectory. After
all of the 3G grooveless bullets were shot Rick went back to shooting the
PJ Creedmoor load. The first shot, after adding 4 MOA to the elevation was
off the nose to the right. The wind had not changed. That meant that the 4
MOA of elevation required to go back to the PJ bullet also required 2 MOA
of left windage, very interesting. I’ve been scratching my head for the past
few years trying to quantify the effects of reduced wind deflection from grooveless
bullets. It is relatively easy to quantify the elevation deltas, but today
was very insightful as it was quite clear that the grooveless bullet was shooting
through the wind far better than the grooved PJ Creedmoor. Using the duel-chronograph
BC calculation technique and a good software program it is also possible to
estimate wind deflection reduction from improved bullet design (grooveless
as well as ogive/nose design.)
So, I’ll lay out there and now, for your consideration, my “Windage Reduction as a Function of Reduced Elevation Requirement Postulate.” The postulate is that for every MOA of reduced elevation from improved bullet design we can expect about ˝ MOA of reduced windage requirement. From a practical perspective, the Lyman Postell and PJ Creedmoor both would have missed the ram swinger off the nose to the right if windage was not adjusted BUT the grooveless bullet would NOT during the wind pick-ups and let-offs. In conditions with any wind there is always a certain level of error in the wind call and sight adjustment as well as condition change from the time the shot is broken and bullet impact.
Certainly there is much more work to do before
I feel satisfied that all that can be squeezed out of our BPCR cast slugs
is realized, but so far between the In-Flight-BC Testing that
Rick is hot to have Brooks make the same mold as the bullet shot better than any I’ve spotted for out of Ricks 45-90 Shiloh Sharps.
Rick used a blow tube during his part of the test and as was said above I wiped with a damp patch pushed through the bore with a brush attached to a flexible rod. My accuracy was better than Ricks, I believe. His was excellent, but I still think better accuracy with the grooveless bullets is had by a simple damp-patch wipe between shots.