If you have run out of topics I may have one. I have spent the time to track down and read the Oberfell and Thompson book, the Brister book, and the Brindle book. Two of the three are out of print so it was a task in itself.
Here is my summary. The O&T book says that only 300 pellets in a 30 inch circle are necessary to cover a 30 inch circle with no patches in the pattern. The graph in the books shows that between 260 pellets and 300 will give you less than a 1% chance of patches.
Bristers book shows the effectiveness of a short shot string and how a short shot string is better. (excluding that tula choke thing)
Brindel says shot string does not matter because it happens so fast anyway.
Assuming you are still awake after my historical literature summary here is the question.
A 1oz load of # 8s has 409 pellets. 70% at 40 yards is still 286 pellets on target(100% coverage). For closer targets a 7/8 oz load with 358 pellets to start with should do the job as well. I realize you would have to pattern each choke at correct distance to determine which choke would deliver the appropriate 260 to 300 pellet dosage. The other positive is the lesser shot gives shorter shotstrings. I am not writing this from a less recoil point of view but strictly from an efficiency point of view. Any more that full pattern coverage is a waste.
I have used 8 shot as an example but this would work with 7 1/2 and 9s as well.
I know you are very fond of saying “less is less”. In Bristers book he clearly showed that more is less because so much shot gets deformed in the long shotstring.
Looking forward to your thoughts on this.
Over the years at ShotgunReport I think I’ve covered most topics, but repeating yourself is part and parcel of the gun writer’s business. It’s also good to consider that a new generation of shooters comes along every four years or so. I read somewhere that the average American adult stays in a recreational sport for that length of time. I think that shooters are all above average in that respect. Still, a bit of repetition never hurts, especially if a little new data is added.
Good for you in reading O&T, Brister and Brindle. Especially Brindle. He’s one of the smartest, but also one of the most difficult to read.
While I would be the last person to argue with this triumvirate of ballistic gods, I should mention that there isn’t unanimity of opinion among the ballistic hierarchy. Things have changed in the past 25 years. Ed Lowry, previous head ballistician at Winchester, and Roger Giblin, a prominent English ballistician, are current authorities who have made some computer-aided advances in the science. Both are believers in the importance of the Gaussian distribution in shotgun patterns. O&T didn’t really explore this aspect as much as they might have. Neither Bristol nor Brindle get into this aspect at all.
Basically, Gaussian theory says that a shotgun pattern distribution will follow the bell-curve. It will be hotter in the center than at the edges. Once you know this, you can pretty much plot two dimensional patterns on your computer with only the input of total pellet count and pellet percentage in the 30″ circle. If you add a factor for the size of the target, you can plot holes. Lowry has done this in his neat ballistic program called “Shotshell Ballistics for Windows” unfortunately no longer available.
With Lowry’s program, once you feed in total pellet count, percentage in the circle and target size, you can discover the effective fringe based on any estimated number of pellet hits per target that you wish. I use Warren Johnson’s “Choke Chooser” 95% chance of a one pellet strike (same as 80% chance of two pellet strike or an average 3 pellet hit) as my criteria.
A clay target is about 4″ in area in edge-on and about 15″ in area full open. I usually compromise with a 6″ target area because most targets have a bit of a turn to them. If you plug in 409 #8s in the load, a 70% pattern, a 6 square inch target and define an effective fringe at 95% of a one pellet strike, you’ll find that you have an effective pattern of 16″ in diameter. Here are the comparison in pattern size based on shot load for #8s, 70% and a 6 sq/in target.
1-1/8 oz #8 (462 pellet count) = 18″ diameter circle 1 oz #8s (409 pellet count) = 16″ diameter circle 7/8 oz #8 (359 pellet count) = 12″ diameter circle (yup, 12″)
Without bothering with shot string, which is effectively dependent on distance and angle, the above figures are the reason I always shoot all that the law allows when I serious about hitting what I’m aiming at. Yes, I’m sure that if you center all your targets, the size of the killing pattern won’t matter. But I don’t center that many of them and I want all the help I can get.
There’s a lot of twaddle about the Olympic load going from 1-1/4 oz (36 dram) to 7/8 oz (24 gram) over the years and scores actually improving. That’s not accurate. In every Olympic sport, each Olympiad people run faster, throw further and generally do better than the people four years before did. It’s the human way. In shooting that is also true, but as shells changed and became less efficient the rate of improvement was slowed down to the poorer ballistics. On average, scores with the current 24 gram load still have not reached the heights they did with the 1-1/8 oz load. If you look at not just the Olympic scores, but also at the off-year World Championship scores, you’ll see that this is so. The 24 gram load is a ballistic nightmare. All the gun makers and ammo makers I talk to comment on how hard it is to get it to pattern properly. Velocities on the 24 gram load have been raised to today’s average speed of 1350 fps to try to eek out the last possible bit of energy from the puny load, but it still is a real handicap.
Obviously the big advantage of the lighter load, in spite of its inferior ballistics, is the reduction in recoil. Many shooters handle one ounce loads better than 1-1/8 oz due to the 20% reduction in recoil. That doesn’t mean the shell is ballistically better. It’s not. It just kicks less. Many of those who don’t use a soft shooting gas gun are forced to go to a less effective shell to lower recoil. It’s as simple as that. They have to trade pattern size for recoil. That’s the price you pay for an O/U. I don’t want to make that trade, so that’s why I often shoot gas guns in competition. Not always, of course, because I get bored, but you get the idea.
Here are the free recoil numbers for the different loads:
1-1/8 oz 1200 fps 8# gun = 20.4 ft/lb
1 oz 1200 fps 8# gun = 16.1 ft/lb
7/8 oz 1200 fps 8# gun = 12.3 ft/lb
I certainly agree that in many respects Brister is right when he says that it’s a bit harder to prevent shot distortion and excessive shot strings in larger loads. But, over the years most of the major development has been in the 1-1/8 oz load, not the 1 oz or 7/8 oz. There are some excellently performing 1-1/8 oz loads out today. Brister wrote his book in 1976. A lot has happened with shotshell quality in the past 28 years. It’s not all that hard to get a short shotstring 70% pattern out of good quality components in 1-1/8 oz. And once you get those percentages the same, less becomes less. It’s also helpful to remember that every 1-1/8 oz load has a 7/8 oz load riding on the front. That rear 1/4 oz doesn’t evaporate and has to go somewhere.
Still, you raise a good question and it’s fun to think about it. In the scheme of things, the best ballistics and chokes will only get you a bird or two out of 100. It’s still the indian, not the arrow.
The Technoid writing for Shotgun Report, LLC
(Often in error. Never in doubt.)