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Thread: chrono difference

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    Default chrono difference

    I got a chrno for Christamas and I finally had a chance to use it. I took me 22-250 and shots a inch with barnes 53 tsx and 37.5 grains of varget. like I said this load shots a 1 inch out of a cheap stevens model 200. here is what I chrnoed
    1. 3807
    2. 3825
    3. 3794
    4. 3833
    5. 3799
    6. 3844
    7. 3785
    8. 3853
    9. 3828
    10. 3846

    There is a difference of 61 FPS from the highest to the lowest readings. Is this exceptable, for some reason I thought it would be closer. any insight would be great.

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    Quote Originally Posted by swapdonkey View Post
    I got a chrno for Christamas and I finally had a chance to use it. I took me 22-250 and shots a inch with barnes 53 tsx and 37.5 grains of varget. like I said this load shots a 1 inch out of a cheap stevens model 200. here is what I chrnoed
    1. 3807
    2. 3825
    3. 3794
    4. 3833
    5. 3799
    6. 3844
    7. 3785
    8. 3853
    9. 3828
    10. 3846

    There is a difference of 52 FPS from the highest to the lowest readings. Is this exceptable, for some reason I thought it would be closer. any insight would be great.
    At a quick glance this seems reasonable. Extreme spread is actually 68 fps (round 7 and round 8), which sounds a bit high to some people but it is actually quite normal to have ES at 50-75 fps in most rifles. You have a standard deviation just shy of 24 fps and that is not going to win BR matches, but for hunting ammo it should work pretty well. There are ways to shrink your ES and SD, but these numbers are not out of line with a lot of loads. If the load is accurate enough for your purposes in the Stevens I would not concern myself with these variations. I would continue to keep records on velocity and secure a larger sampling size for more valuable comparisons.

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    Quote Originally Posted by 1Cor15:19 View Post
    At a quick glance this seems reasonable. Extreme spread is actually 68 fps (round 7 and round 8), which sounds a bit high to some people but it is actually quite normal to have ES at 50-75 fps in most rifles. You have a standard deviation just shy of 24 fps and that is not going to win BR matches, but for hunting ammo it should work pretty well. There are ways to shrink your ES and SD, but these numbers are not out of line with a lot of loads. If the load is accurate enough for your purposes in the Stevens I would not concern myself with these variations. I would continue to keep records on velocity and secure a larger sampling size for more valuable comparisons.

    you are right, I guess I cant subtract today. Im at the book max, but not seeing any pressure signs. The best group and I have got is .830 with the average about 1.10. I know this is a cheap hunting rifle, but i want to get the best load that I can. I do notice that almost all of my groups are two bullets almost touching each other and then one will be high a 1" or so. I know it means something I just cant remember.

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    Quote Originally Posted by swapdonkey View Post
    I do notice that almost all of my groups are two bullets almost touching each other and then one will be high a 1" or so. I know it means something I just cant remember.
    I think groups like that simply means that most bullets don't land in one hole. Seriously, sounds like you have a great load that should work perfectly for its intended purpose.

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    I should have never got into reloading. now I want every gun to shoot in one hole. Then I got a chrono and now even pickier. I have been going so far as to loading a 1/10 or a grain and making the bullet longer and shorter.

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    The third round being a flyer (if you can call sum MOA off a flyer) is usually heat moving things around. Could be a lot of other things also but likely heat. If it's shooting like that I would just pet it and shoot some more! Savage has always made good barrels even in their cheap Stevens line.
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    The spread is most likely not a Chrono issue but a reload, prep, charge issue. Once all pieces of brass are prepped identical and weigh virtually the same and the powder is all hand weighed to the same value your spread will most likely be within 1% of your velocity and your SD will be less than 10. In your example an extreme spread less than 39fps would be sweet. Once your spread is tighter your groups will usually get tighter too.

    Once you get as good as you think you can get try a different primer with that load and see what happens. In my 375 example I tried Fed 215, 215M and CCI 250's before I settled on the CCI 250. It shot the same velocity as the 215 and they shot 40fps faster than the 215M. The CCI 250 had a tighter spread in my example.

    Welcome to the joy's of reloading.

  8. #8

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    Quote Originally Posted by swapdonkey View Post
    I got a chrno for Christamas and I finally had a chance to use it. I took me 22-250 and shots a inch with barnes 53 tsx and 37.5 grains of varget. like I said this load shots a 1 inch out of a cheap stevens model 200. here is what I chrnoed
    1. 3807
    2. 3825
    3. 3794
    4. 3833
    5. 3799
    6. 3844
    7. 3785
    8. 3853
    9. 3828
    10. 3846

    There is a difference of 61 FPS from the highest to the lowest readings. Is this exceptable, for some reason I thought it would be closer. any insight would be great.
    Most off the shelf chrony's are not precision instruments. Your chrony could easily be off up to 3% give or take. I have two chrony's I shoot back to back occasionally and they never agree. Not only do they not agree, but their differences have varried anywhere form 5 to 60 fps. If your chrony says 3785 on shot 7 it could easily have really been 3805 and if it said 3853 on shot 8 it could have easily really been 3823. Just because your numbers tell you that you have a spread of 68 doesn't mean it's so. In fact the odds are way against it. Another thing to keep in mind is that a spread of 70 fps is probably not going to make a lot of difference at 100 yds.

    I've shot a couple of groups in the .4"-.5" at 212 yds with loads my chrony was telling me spreads similar to yours... and a 1.8" group at 427 yds.

    Believe your shooting. Your chrony will lie to you, or at least exagerate some.

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    I hate to dispel such closely held myths as this crap about low ES mean small groups, but I'm afraid that is the truth. Play this game with a crony with a rifle that is known to shoot aggs under a .250" five shot group and if you were to crony the loads you will find a large ES. What does this tell you? Sometimes I even wonder why people even print ES in articles about good grouping rifles. ES is a mental deception, do not get let down that path. I have know world bench rest competitors to be led down this same path, they never had paid any attention to any of these things when they were setting world records. Pay attention to your wind flags and try to shoot your groups in the same conditions. You don't have 4 or 5 wind flags to shoot your groups and have a crony instead? Loose the crony and get some flags and then I will quite laughing.
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    Quote Originally Posted by Big Al View Post
    I hate to dispel such closely held myths as this crap about low ES mean small groups, but I'm afraid that is the truth. Play this game with a crony with a rifle that is known to shoot aggs under a .250" five shot group and if you were to crony the loads you will find a large ES. What does this tell you? Sometimes I even wonder why people even print ES in articles about good grouping rifles. ES is a mental deception, do not get let down that path. I have know world bench rest competitors to be led down this same path, they never had paid any attention to any of these things when they were setting world records. Pay attention to your wind flags and try to shoot your groups in the same conditions. You don't have 4 or 5 wind flags to shoot your groups and have a crony instead? Loose the crony and get some flags and then I will quite laughing.
    Depends on the range to the targets doesn't it Big Al? For under 200 yards I agree 100%, but I also know world class LR shooters that develop all of their loads on chronographs without considering 100-200 yard targets. IME different disciplines have different requirements, but I do agree that for a lot of shooting ES is unimportant and for normal hunting loads I could care less, which was the tenor of my original reply on this thread.

  11. #11

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    Quote Originally Posted by 1Cor15:19 View Post
    Depends on the range to the targets doesn't it Big Al? For under 200 yards I agree 100%, but I also know world class LR shooters that develop all of their loads on chronographs without considering 100-200 yard targets. IME different disciplines have different requirements, but I do agree that for a lot of shooting ES is unimportant and for normal hunting loads I could care less, which was the tenor of my original reply on this thread.
    I've seen this subject debated a good bit. Some guys use the ES's from their chronies to pick good loads for accurate long range shooting and some guys use ladder testing which is basically shooting different groups with different loads and measuring the verticle disperssion to find the best node. That said, ladder testing is best done at longer ranges, 600 yds or farther and the farther, the better. But if you're not shooting that far, who cares?

    If anyone reading this thinks their Sportsman Warehouse purchased chrony consistintly shoots + or - 5 fps or better, I ve got some real estate deals for you. I would be surprised if even the Oehler owners are getting that level of accuracy on a consistant basis. If you have a good off the shelf chrony, you might be getting + or -10 fps. Chances are it's not that good and you will occasionally get get some big hickups with it. There is a reason why some chronys cost $100 and others cost $600 or more. I have seen too much weird stuff mine to bet the farm on them.

    Another thing... even if you had a real good chrony, a low ES doesn't necessarilly mean an accurate load. You could have a (actual) low ES and have bullets going everywhere. But... for long range accuracy, you do need a low ES. Everything else being equal, a 50 fps ES will mean a 2" difference in drop @ 1000 yds. A 50 fps ES at 100 yds don't mean squat. If I didn't shoot farther than 400 yds, I wouldn't have a chrony, and I dont use my chrony to pick a load. I use target result to do that. I use chrony data to help me estimate drop and windage.

    Have fun with your toy, but dont expect it to be what it isn't. It will give you a ball park idea of your velocities, but probably not much more than that. You will probably see significant day to day differences, especially when light conditions change. I have seen average velocities drop close to 50 fps instantly when a high overcast partially obstructs the sun, etc. And something to remember is to align it exactly the same from session to session. A slight difference in level or straightness will result in a measured distance error between sensors.

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    Member Big Al's Avatar
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    Where is their a range in Alaska with a measured distance of more than 300 yards that you can used more than twice a year? I do not know of any measured distance ranges out to 600 or a thousand yards. Good luck using a Oehler 35 or 43 which you can no longer buy and haven't been able to get for about five years now, unless you can find used or have one already.
    "The tree of liberty must be refreshed from time to time with the blood of patriots and tryants." (Thomas Jefferson

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    Consider that 50 is less than 2% of 3000 - I think you're doing just fine.

    Also keep in mind that many chronies operate with a tolerance of + or - a percentage or two (or five) depending on model.

    Nate

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    Quote Originally Posted by Big Al View Post
    I hate to dispel such closely held myths as this crap about low ES mean small groups, but I'm afraid that is the truth. Play this game with a crony with a rifle that is known to shoot aggs under a .250" five shot group and if you were to crony the loads you will find a large ES. What does this tell you? Sometimes I even wonder why people even print ES in articles about good grouping rifles. ES is a mental deception, do not get let down that path. I have know world bench rest competitors to be led down this same path, they never had paid any attention to any of these things when they were setting world records. Pay attention to your wind flags and try to shoot your groups in the same conditions. You don't have 4 or 5 wind flags to shoot your groups and have a crony instead? Loose the crony and get some flags and then I will quite laughing.
    Thanks Beeg AL:

    All these people who subcribe to using ES, will also say that, often the loads that have the smallest ES, aren't the most accurate.

    And, it has little to do with what range you're shooting. I've heard and read it from 1K BR people. I think they mess with it because it makes them feel like their involved in something scientific. It's scientific all right, but it's Experimental Science.

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    Default Something to consider

    Quote Originally Posted by MontanaRifleman View Post
    Another thing... even if you had a real good chrony, a low ES doesn't necessarilly mean an accurate load. You could have a (actual) low ES and have bullets going everywhere. But... for long range accuracy, you do need a low ES. Everything else being equal, a 50 fps ES will mean a 2" difference in drop @ 1000 yds. A 50 fps ES at 100 yds don't mean squat.
    BUT, is "everything else" ever equal?

    If you have a 50 fps spread, that would mean that the bullet would leave the barrel at a different spot, or vibe, in the barrel, which can make for a higher or lower impact, at any range. And, effect other things also.

    "I've seen this subject debated a good bit", too. I've concluded the fps, at whatever range, drop, statement is a meaningless one, because of the many other factors that must needs be considered, especially at longer ranges.

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    Quote Originally Posted by Smitty of the North View Post
    BUT, is "everything else" ever equal?

    If you have a 50 fps spread, that would mean that the bullet would leave the barrel at a different spot, or vibe, in the barrel, which can make for a higher or lower impact, at any range. And, effect other things also.

    "I've seen this subject debated a good bit", too. I've concluded the fps, at whatever range, drop, statement is a meaningless one, because of the many other factors that must needs be considered, especially at longer ranges.

    Smitty of the North
    You're right... there may be a number of variables and the difference in velocity may or may not find another vib and IMO a chrony is a marginal instrument for determining actual ES... Which is part of my point. Use actual shooting results to pick your load. If I knew for certain that I could trust my chrony, I would go with low ES along with a good group.

  17. #17

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    I won't get into the discussion about the chrony, but in reference to how the rifle is shooting, there are a few things you can try to shrink your groups. First, I would check the bedding to see if the barrel is free floated or has any pressure points. That could be where your one flyer is coming from. Also, in your reloading, don't be afraid to try a few different kinds of powder with the same bullet. Different rifle/bullet/powder combinations work better than others.
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