1. Attention: We have put together a thread with tips and a tutorial video to help with using the new software. Please take a moment to check out the thread here: Trapshooters.com Tutorial & Help Video.
    Dismiss Notice

Help-Shot Velocity ?

Discussion in 'Uncategorized Threads' started by phirel, Oct 31, 2008.

Thread Status:
Not open for further replies.
  1. phirel

    phirel TS Member

    Joined:
    Jan 29, 1998
    Messages:
    9,556
    Can anyone furnish me with the retained velocity of #8 and #7.5 shot at 35 yards when the shot leaves the barrel at 1200 and 1250 ft/sec?

    Pat Ireland
     
  2. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,848
    Pat, that "shot leaves the barrel" part is a complication I'll only get into if you want, but let's call "shot leaves the barrel" the thing Ed Lowry's program refers to as 3-foot velocity since I think is the ratios, rather than absolute speeds, which you are after.

    8's, three foot v=1200, at 35 yards velocity = 652 fps

    8's, three foot v=1250, at 35 yards velocity= 668 fps

    7 1/2's, three foot v=1200, at 35 yards velocity= 670 fps

    7 1/2's, three foot v=1250, at 35 yards velocity = 687 fps

    Neil
     
  3. Jim101

    Jim101 Active Member

    Joined:
    Jan 29, 1998
    Messages:
    1,942
    Location:
    Knob Noster, Mo
    I suspect Pat's reason for asking the question is to show just how small the difference is at target breaking distances.




    Jim
     
  4. phirel

    phirel TS Member

    Joined:
    Jan 29, 1998
    Messages:
    9,556
    Neil, thanks. It looks like 7.5 shot gains around 20 ft per sec at 35 yards over #8 shot. Just using shot velocity (ca 670 ft/sec and target speed at 35 yards (35 MPH), if I hit the right keys on my calculator, the target will travel less than 1/10 of an inch further if hit by #8 shot than it would travel if hit by #7.5 shot.

    Neil partially convinced me to use #8 shot for handicap in another thread earlier this week. These numbers have convinced me a little more. I don't know if I am ready to make the change, but the way I have been shooting handicap the last few weeks tells me I have nothing to lose.

    Pat Ireland
     
  5. Didreckson

    Didreckson Active Member

    Joined:
    Jan 29, 1998
    Messages:
    883
    Location:
    Central California
    There is a fellow by the name of Ron Alcoriza that shoots in Stockton occasionally. I consider him a pretty fair shot, and he shoots nothing but light 8's for everything. Since he has missed more targets than I probably will hit in my lifetime, I value his opinion greatly. Now if he would just get that demo Kolar T/A combo in I want to try out.
     
  6. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,848
    Remember, Pat, the argument for shooting 8's at handicap concentrates on the case (s) where pellet-count is a problem, an example being lighter than max shot weights. You, with your Silver Bullets, don't have to be so concerned, as long as you shoot without delay.

    I just bought 20 more flats of 7 1/2's but next week may shoot 8's to see what happens.

    By the way I just spent the day testing 7/8 oz loads of 8 1/2's against each other and against 1 1/8 oz
    light 7 1/2 Gold Medals. The lighting was tricky but I trust I'll have something in the camera to work on. I must say, as I laid them out face down, comparing one to another, I didn't see much difference. Pellet counting will tell the tale, of course, but nothing's jumped out at me yet, except that seven and a halfs are _way_ bigger than eight and a halfs.

    Neil
     
  7. phirel

    phirel TS Member

    Joined:
    Jan 29, 1998
    Messages:
    9,556
    Neil- I remember that your data was referring to lighter loads. But, if the smaller shot are best for 1 oz loads, why not 1 1/8 oz loads?

    Pat Ireland
     
  8. Neil Winston

    Neil Winston Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    7,848
    It's an example of two countervailing influences - both based on the idea"enough is enough" - and which of the two concomitant "not enoughs" you think is the more likely to cost you.

    1. With a heavy load (and shooting without much delay) you are going to have enough pellets in the inner 10-inch circle for my Shogun-Insight program to predict that there is a 100%, or very near to it, probability of putting a pellet on a target. And that's with 7 1/2/s or 8's, generally speaking. In this case the "enough" is pellet count and you can begin to worry a whether a single 8's will break that target near that 100% level as well. If you have any doubt of that (I have very little) then there's no point in not shooting 7 1/2's since you have enough of them, pellet-count-wise, in any case.

    2. With lighter loads the "enough" has to be the high probability of a single 8 pellet breaking a target. And the "not enough" you begin to run into is pellet count with 7 1/2's at longer yardage. You pretty much have to so to smaller shot to get the probability of a single-pellet hit up high enough that you aren't losing at least a few (but not in every event) targets to too "thin" a pattern.

    I was counting pellets in the Gold Medals I patterned yesterday and man are 7 1/2's big! I've only started on the data, half a dozen of 30 patterns analyzed, but once again I seem to be headed for getting about what I usually do, with little evidence for the sort of magical effects both magazines and some posters here routinely predict.

    Neil
     
  9. zzt

    zzt Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    3,460
    Location:
    SE PA
    Pat, I have a different outlook on this. It is true that enough is enough, but why settle for barely enough when you can have more. We have done the velocity thing to death. Speed doesn't kill, retained energy does.

    It is pretty widely accepted that a pellet must have .5 ft/lb of retained energy to reliably break the target. In my spreadsheets, I use .6 ft/lb just for an extra margin of safety. In reality, I believe the "correct" number is closer to .4, just by observation. In any event, let's use .5.

    9s launched at 1200fps retain .5 ft/lb at 40 yards. That is a quick 27 yard handicap shot, so I put that in the barely enough category. There are multiple target hits, but I don't consider the breaks satisfactory. So here is one boundary.

    Working with SBW and Shotgun Insight, you quickly learn that the number of pellets in a goooood 1 1/8 7 1/2 load are barely enough for 27 yard handicap shots. There are just not enough pellets to guarantee you a 100% chance of a one pellet hit on every target. I've seen data both ways, but my personal feeling is that it may be enough in the West, but not in the East. I'm talking 100% here, not 99.9 or 99.99. So this establishes the other boundary.

    So if you accept my boundaries, you need more pellet energy than 9s and more pellet count than 1 1/8oz 7.5s to get more than barely enough at the 27 yard line.

    That leaves a big middle ground where you can_have_more_than_enough. When I first started shooting again I quickly realized 8s were more than enough. Then I remembers my youth when all we shot was 1 1/8oz #8 @1200fps. Why? Because that's what the loading machine came set up to load. 19 grains of Red Dot and 1/18oz 8s. I mention this because I used the same load for protection shoots where second shots are looong, and 8s still broke them. I use 8s for almost everything.

    Lately, I've been retesting that decision. In late spring I had Kerry Allor turn my O/U barrels into Bunker barrels, so naturally I had to find out how they worked. While shooting I noticed, surprisingly, that my baby bunker loads (24g, #8, 1300fps) broke handicap targets exactly as well as my standard handicap load did (1.125oz, #7.5, 1150fps).

    A quick look at my tables showed retained energy at 40 yards was virtually identical (.96 vs. 1.02 ft/lb.) so you would expect the breaks to be equally energetic, and they were. Substituting 8.5s resulted in more smoke, but less energetic breaks (.73 ft/lb). Moving to 7.5s (1.17 ft/lb) resulted in more dramatic breaks, but fewer, and larger, pieces. So the math backs up observation.

    So where does that leave us. I'll admit a prejudice against 9s for ATA trap. It's a mental and visual thing that defies logic, but that's how it is. So leaving 9s out of the picture, what can you do to get the most "enough"? Again, SBW gives you the numbers.

    If you want the biggest, most effective pattern you can get for singles, use 1 1/8oz #8.5 with a choke that gives you a 95% PE at target distance. That will provide a 17" diameter zone where there is a 0% chance of a 0 pellet strike. That is easily achieve with a good Modified or ordinary IM or Full at singles distances.

    For handicap, it would be unusual to get a consistent 80% PE at 40 yards using 8.5 shot. 75% is more like it. So the area that provides a 100% chance of at least a 1 pellet hit is only 11.2" in diameter. It is possible to get 80% patterns using 8 shot, so the corresponding diameter is 9.6". Just for comparison, for 7.5 shot at an 80% PE the diameter is only 2.2".

    So once again, the numbers match my observations on the line. My most consistently high singles scores were shot using a Wilkinson barrel and .022" choke and 1 1/8oz #8.5. I'm recoil sensitive, and you gain little in the way of retained energy at 40 yards by pushing 8.5s faster, so for handicap I stick with 8s. There speed does make a difference. 8s @ 1150fps retain .81 ft/lb. That already is more than enough. Sure kill area is almost at the max you can get, so I'll accept the trade off.

    Said another way, for AA shooters, 95% PE at target distance is the sweet spot for the largest sure kill area using 8s or 8.5s. Higher or lower PEs diminish the area. For AA27 shooters, the decision is whether to use 1 1/8oz #8.5s for the largest sure kill area, or 8s for more dramatic breaks at the cost of a slightly smaller sure kill area. Velocity doesn't matter here. Shoot the speed you like. I can easily tell the difference in time of flight between different loads from the 27. Even though my shoulder does not agree, my brain says 1200fps is "right". Going from 1150fps (bang.....break) to 1200fps (bang..break) seems to be the threshold for me. 1235fps doesn't add enough more to put up with the recoil.

    Try the 8s. You_will_like them.
     
  10. 870smokim

    870smokim TS Member

    Joined:
    Feb 18, 2007
    Messages:
    70
    Good thread, just what I like to read.
    870 smokim Joe
     
  11. Rvator97

    Rvator97 TS Member

    Joined:
    Jan 29, 1998
    Messages:
    335
    zzt: good post up to the part about "i can easily tell the difference in time of flight...." Gimme a break! We're talking about a few milliseconds difference between 1150s and 1200s!!!LOL
     
  12. phirel

    phirel TS Member

    Joined:
    Jan 29, 1998
    Messages:
    9,556
    Excellent post by Neil and zzt. Both are backed with sound logic and some data. But they reach different conclusions. I need to study this question more.

    zzt- I did get your e-mail and spread sheet. MIA- I did get your chart. Thanks to both of you. Now, I have to do a little studying.

    Pat Ireland
     
  13. phirel

    phirel TS Member

    Joined:
    Jan 29, 1998
    Messages:
    9,556
    Eddie- Your point is clear and accurate. My handicap loads did result in my purchase of a PFS. That was one of the few smart moves I have made in this game.

    Pat Ireland
     
  14. dmarbell

    dmarbell Active Member

    Joined:
    Aug 26, 2006
    Messages:
    1,572
    Based on my observations of the better shooters at area ATA shoots, singles birds are shot in about a second or less from the launch of the bird. Birds launched at 42 mph (61.6 fps), going directly away from you, travel 20.5 yards in one second. That means the birds are 36.5 yards from the 16-yard shooter in one second.

    Trap birds don't go directly away from the shooter, but are launched at slight angles upwards and sidewards. The also decelerate quickly. That means, that if shot withing one second, they are closer than 36.5 yards, on average, when shot from the singles line.

    Do these observations and my logic seem right?

    Danny
     
  15. phirel

    phirel TS Member

    Joined:
    Jan 29, 1998
    Messages:
    9,556
    Danny- One second between when the bird appears and most shooters shoot is much too long. A half to 3/4 of a second would be closer to the time experienced shooters require. Also, during this half second or so, the 43 MPH bird slows down to around 35 MPH.

    Pat Ireland
     
  16. dmarbell

    dmarbell Active Member

    Joined:
    Aug 26, 2006
    Messages:
    1,572
    Pat,

    Your reply leads me to believe that most singles birds are shot at less than 30 yards from the shooter. 3/4 second for a bird launched at 43 slowing to 35 mph is about 30 yards from the 16-yard shooter, for a bird going directly away. Up and side angles would mean the birds are less than 30 yards away, right?

    Danny
     
  17. dmarbell

    dmarbell Active Member

    Joined:
    Aug 26, 2006
    Messages:
    1,572
    Note: for this post, I'm talking about singles only.

    ... back to the point of my question to Pat, about the fact that most singles birds are shot at 30 yards or less. Assuming that is true.

    1 1/8 oz. of #9 with an IC choke at 30 yards puts 507 pellets in a 30" circle (77% of 658). Each pellet retains 0.83 ft-lb at 30 yards. Pellets per sq inch, 0.717, ft-lb 0.595.

    1 1/8 oz. of #8 with a M choke at 30 yards puts 383 pellets in a 30" circle (83% of 461). Each pellet retains 1.29 ft-lb at 30 yards. Pellets per sq inch, 0.542, ft-lb 0.699.

    1 1/8 oz. of #7.5 with a M choke at 30 yards puts 327 pellets in a 30" circle (83% of 394). Each pellet retains 1.59 ft-lb at 30 yards. Pellets per sq inch, 0.463, ft-lb 0.736.

    So, why aren't #9 shot loads of 1 1/8 oz. with IC chokes good for singles, assuming relatively fast shots?

    Danny
     
  18. zzt

    zzt Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    3,460
    Location:
    SE PA
    Danny, first off, your retained energy figures are wrong. According to Ed Lowry, who wrote the modern, correct shotgun ballistics tables, retained energy of a #9 pellet launched at 1150fps is .67 ft/lb at 30 yards. Launched at 1200fps it only rises to .7.

    So to get the biggest sure kill pattern for singles you want a choke that will deliver a 90% PE at target distance with 1.125oz #9. That will give you a sure kill diameter of 18.6" If you are talking 30 yard hits, that is a decent LM choke or a bad Modified choke.

    Personally, I want a little more retained energy than that, so the lightest I'll use (unless the shells are free) is #8.5 shot. That retains .88 ft/lb at 30 yards and provides much more satisfying breaks. Enough that I am willing to give up 1.6" of sure kill diameter to use them.
     
  19. phirel

    phirel TS Member

    Joined:
    Jan 29, 1998
    Messages:
    9,556
    Danny- There is another consideration that I believe is very important. I want enough shot in the center of the pattern to reduce the target to a puff of smoke, not just break the target. This lets me know if I have properly center the target in the pattern. If I get a weak hit, that lets me know I did not center the target. If I get two weak hits in a row, that lets me know I need to change something or a miss is coming. I believe a full choke is best although I could live with a tight improved modified.

    Pat Ireland
     
  20. zzt

    zzt Well-Known Member

    Joined:
    Jan 29, 1998
    Messages:
    3,460
    Location:
    SE PA
    Just to avoid any confusion, the sure kill pattern diameters I listed in my posts have enough pellets in the core to reduce any centered target to nothing but smoke. The average number of pellets hitting the 6 square inch target placed anywhere in the sure kill area is 5.3.
     
Thread Status:
Not open for further replies.
Search tags for this page

shot retained celocity