Blown Patterns


Dear Bruce,

It’s been some time since I shot trap competitively. Heck, handicap loads were 3 drams and 1 1/8 ounce of your favorite shot in those days and no one ever heard of choke tubes. The trend I see for a lot of clay target sports is lighter yet faster payloads, sometimes reaching over 1400 fps in the sporting clays game.

Are blown patterns, that is, patterns losing their density due to velocity, something to be concerned about? I’ve read many articles over the years about lowering velocities to increase pattern densities so I’m concerned that too much velocity might have the opposite effect. Your discussion about smaller shot charges helping to decrease recoil was most enlightening, but should there be any concern about excessive, or increased, velocity?

Any enlightenment you can provide will be gratefully appreciated.

Sincerely,

Dennis
A reformed trapshooter

Dear Dennis,

“Blown” patterns can result from a poor gas seal or a wad disrupting the shot charge. This is simply due to a faulty shell design, inferior wad or poor shell assembly. Higher velocity and/or heavy payloads will damage more shot due to setback, but this only degrades the pattern. It doesn’t “blow” it.

Shot which is less round due to setback will not pattern as tightly as perfectly round shot, but it won’t be too far away either. My tests of the cheapest chilled shot vs the hardest “magnum” shot showed about a 10% pattern difference. IE- the good stuff shot 60% in a particular barrel and the soft shot was 50%. Certainly a difference, but hardly a “blown” pattern.

I don’t know whether light fast loads deform more shot than heavy, moderate loads. You’d have to pattern test the particular shells to find out. Personally, I’m not a fan of light fast loads because I know that pattern fails before energy. The heavy loads with the full compliment of pellets always pattern better than the light fast guys that use small shot charges. The percentages of the heavy load may not be better, but there are so many more pellets to start with that the actual pellet count in the pattern is higher. It’s pellet count, not percentages, that break targets (Gee, I wish I’d been the first to say that instead of about the one thousandth.)

Most of the work on the light fast loads has come from people who used light loads to avoid recoil. Nothing wrong with that if your gun kicks you too much. But, just as we do with every other thing, once light loads became popular, people wanted to “improve” them by increasing the speed. And thus raising the recoil.

In the case of the ISSF Olympic 24 gram loads (7/8 oz) at a nominal 1350 fps, they went with the extra speed because they were mandated to use dinky 24 gram loads by the rules. They are just trying to max the 24 gram loads. Remember, the 24 gram loads were adopted by the ISSF to LOWER scores. This they have done. ISSF scores are now approaching what they were in the old days, but you must remember that Olympic athletes get better every year in all the sports. The fact that the little 24 gram loads have delayed this inevitable progress is ample proof of their inferiority. World class ISSF shooters are definitely better than they were 20 years ago, but the scores are the same. That’s due to the handicap imposed by the shells.

I’ve never fully understood the need for hyperspeed loads, unless it’s a demonstrated energy need. Many people like the fast shells because they don’t need as much lead on longer targets. True enough. But, lead is just something you get used to. It’s not an absolute of any kind. If you practice with 1200 fps loads all the time, you will learn the leads needed with those loads. A shell that gives you a shorter lead is neither here nor there.

In exchange for the extra speed, you give up pellet count if you are going to keep the recoil roughly the same. That’s not a trade I’m willing to make. The added energy of the high velocity shell pellet is minimal. A #7-1/2 started at a stately 1135 fps has .8 ft/lb energy at 60 yards. The same pell et started at 1330 fps only has .9 ft/lb at 60 yards (Lyman’s reloading book). I’d sure rather have 25% more little lead soldiers on my side than that tiny bit of extra energy.

Bruce Buck
Shotgun Report’s Technoid

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One Response to Blown Patterns

  1. james rennie says:

    Re blown patterns : Remember the first steel pellet shells on the market ? They were very prone to “blown ” patterns, i.e. all the shot in a ring around the outside of a 30 inch circle and none in the middle ,with a blank area the size of a basketball. They were not extremely fast velocity loads. Eventually , manufacturers came out with better shot cups, wads, powder that almost eliminated the problem. I say almost, because you can still find examples in the steel shotshells sold today……..Jim Rennie

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