To my knowledge, there are no 26 & 28gm 'international loads' any longer - they are 24gm (slightly less than 7/8oz) and yes, they are legal for ATA as long as the shot is not plated, and the speed is less than 1350fps/412m-sec.
One ounce loads (incl 26 & 28gm) are limited to 1325fps/404m-sec.
From the ATA rulebook, itsownself:
<blockquote><i>"3. Any load with a velocity greater than 1290 FPS (Feet Per Second)with maximum shot charge of 1 1/8 ounces, or 1325 FPS with a
maximum shot charge of 1 ounce, or 1350 FPS with a maximum
shot charge of 7/8 ounces or less, as measured in any individual
shotshell. These velocities are maximum and no individual shotshell
shall exceed these limits for the designated shot charge. In addition,
no load containing more than 1 1/8 ounces or any shot larger than
Number 7 1/2 can be used. Shot charges are maximum and no
charge may exceed the charge amount by more than 3%."</i></blockquote>
In practical terms, even if you were shooting labeled 1360fps (RIO ST24) or B&P F2-Mach (1365fps), and you were protested and checked, I doubt you'd even get an eyeroll from officialdom.
Not sure why you'd want to shoot these loads regardless. I've been in europe for work alot this year and shot olympic trap several weekends. the ammo is expensive at 50-55 euros per flat and it kicks very hard. Not at all pleasant to shoot and with only 24 grams you are at a significant disadvantage on pellet count.
Yes.. Europe it cost in Euro.. what we pay in dollars.. 24 gram is the standard.. but some practice with 28 gram.. They are cheaper.. Everything being equal.. a 24 gram shell at 1330 has 12.16 ft. pounds of free recoil.. A 1 1/8oz at 1220 has 15.96 pounds of free recoil.. If everyone shoots the same shell.. there is no disadvantage.. except to your ego..
If ATA was changed and ONLY 2.5" 410 was legal.. and with #8 shot only..The winners circle would have the same residents.. and so would the whiners circle..
What happens when they find a pellet larger than #7.5? I can't believe that factory #7.5s have every pellet smack bang on exactly 95.00000000 thousands of an inch. As I read that rule (as posted above), one pellet greater than 95-thou and you're out.
Amdrew- Very good point. I measured the shot in a popular brand of imported shells. I found the same size spread of shot in boxes labeled #8 as I found in boxes labeled 7.5. Some of the shot in these factory loads were a little larger than 7.5 shot. I have also found some shot in bags of imported shot labeled 7.5 to be larger than 7.5 shot.
Most egregious, for some years I made shot. I could successfully make every shape of shot except round. The stuff shot very well. Determining the size of slightly oval shaped shot is difficult. On the long axis the shot was larger than 7.5 but on the short axis the shot was between 7.5 and 8.
Lacking any reasonable alternative, I would conclude that if one shoots new shells from a box with the shot size labeled 7.5, or reloads shells using a bag of shot labeled 7.5, the shells are legal. This of course places more importance on the label than the actual shot size but I don't know what else to do.
Coach, while "most" bunker loads may fall below the 1350 fps threshold, the ones cited by Bob didn't and they were so labeled. The ATA would look at the box, believe it, and disallow the shells before shooting, disqualify after.
Based on Andrew's recommendation, I got a copy of Ed Lowry's book on ballistics. One of the things he mentions is that for most people, the feeling of kick tracks the energy of the shell rather than its momentum. If that be true, the kick of a 7/8 load going 1300 is about the same as a 1150 load of 1 1/8. If young shooters want less recoil, and 7/8 is fine except in competition, then the parents have to be reminded to keep the speed down.
Pat, It's not a very good rule is the root (and route?) of the problem. It's a bit like that cheerleader's outfits being pornographic debate, you know, "you can instinctively tell when they are, but you can't draft a good law against it" problem. Not that I could see a problem with the cheerleaders anyway mind. Knowing what I do now about how the likelihood of pellets breaking the targets varies with pellet size, there's no advantage to using larger pellets; the lower pellet count effect starts to be bigger than the higher impact energy effect once around ~US #7.5s. Apart from drop zone considerations, there's no point in restricting pellet sizes.
Neil, I vaguely remember ol' Ed giving a very obfuscatory explanation for recoil. I remember reading and having difficulty following it. Are you sure you have understood it right? The "easy" way is simply MV=MV for the gun and load. If you have a fixed load weight, then recoil energy scales with muzzle energy. But if you halve the payload weight and double the muzzle velocity, the muzzle energy has doubled but the MV of the gun is unchanged and hence also the recoil energy.
On a slightly different tact, why not use bunker loads in ATA? Perhaps it is just me, but the recoil from those has always seemed lighter than Remington Nitro or other 1250fps 1 1/8 load. Add this to the mix, for the reloaders you do get more shells loading 7/8 or 24g loads. Cheaper perhaps? As I recall ISSF went to 24g to "make the game harder" as if bunker needed to be. Anyway, I can't help but wonder what effect it would have on the number of 100+ scores.
Both Neil.. and Dr. Jones have both proved..and quite easily.. The probabilities of hits is higher with 1 1/8oz.. Period.. there is no where to go from that.. I will tell you..the 24 gram can do the same.. if you are perfect.. every shot perfect.. you are a perfect shooter..and you shoot a perfect barrel.. Than everything outside a 18" circle at 35 yards is just wasted with you..
If you are the average shooter.. that extra useful pattern will be very helpful on a windy day at the 27.. Many of the best trapshooters shoot light shells.. with 1 1/8 oz.. Less recoil.. infact.. very similar to the 24 gram bunker shell.. but still sport a much larger effective pattern..
On the up side.. a lighter recoiling shell that cost you less to load might produce more rounds of practice..as well as keep the flinching trool away longer.. You'll stay in the gun.. and learn much quicker..