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RayH
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Chronograph use help needed
Oct 1st, 2013 at 6:19pm
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I'm refining bullet - load combos for use with my .32-20 CPA. How and when does chrono. use become necessary and how does the info. gathered guide me in load/bullet development/selection?
  

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MikeT
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Re: Chronograph use help needed
Reply #1 - Oct 1st, 2013 at 8:48pm
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If you do not need a specific MV, then I can not see a need for a chronograph.  The target will tell you if your load is working.

Not only that, look at all of the good trigger time you will get while developing a load.  Cool

Keep on hav'n fun!
MikeT
  
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frnkeore
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Re: Chronograph use help needed
Reply #2 - Oct 1st, 2013 at 9:06pm
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I've faithfully used a chronograph for load developement since '86 but, it's not a necessity if you know approximently what others use for powder charges. It is a necessity if your using a different powder in a new or different cartridge. Like when I started reloading and BSing 22rf.

It can also weed out powders and loads that have no hope of working, such as a load that has 100 fps extreme spead or when you get a bad flier, to know if it could have been a large ES. It can also be a valuable to test out primers. It a good tool to use but, we all shot of a long time w/o them.

I use mine a little less now but, I'll always use it.

Frank
  

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John Boy
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Re: Chronograph use help needed
Reply #3 - Oct 1st, 2013 at 10:57pm
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* Use chronograph when working up powder charges
* Use chronograph readings for trajectory table (velocity) when the right charge is determined for vernier settings.  Especially for calibers that are shot long range out to 1000yds & 200-500 meter steel
  
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JLouis
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Re: Chronograph use help needed
Reply #4 - Oct 1st, 2013 at 10:58pm
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Okie once you get the rifle shooting record the velocity with that particular bullet. When you change lots of either powder or primer you might have to tweak the load to get it that ideal velocity back. It also comes in handy when you want to go past the first node in search of the second one. It tends to be in the 1450-1500fps range and it's nice know just where you are at while looking for it. In your case it would be on the border line of being to hot so you want to very carefully sneak up on it a little at a time. You will reach a point with your case where just add a tad more power, a tenth or two will create a pressure spike and put it over the edge of being safe and cases will start separating on a quite regular basis. When you get that close your velocity will also start showing real big increases. Other than than that as Mike pointed out it's not much help in actually developing the most accurate load.

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40_Rod
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Re: Chronograph use help needed
Reply #5 - Oct 2nd, 2013 at 9:05am
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The chronograph is good for 2 things. First evaluating your loading technique. Second reading the bullet speed that is best for your gun. Please notice that I did not say finding the best speed.
  When you start with any powder and measure it is good to run your loads over the chronograph to evaluate your load technique. You are looking for the smallest ES that you can get to ideally under 10 FPS. When your combination of powder, primer and measure technique get your E.S. down as far as possible you can concentrate on finding a speed that will give you the best accuracy. For this part you don’t need the chronograph. 
Start by shooting 3 shot groups moving a couple of clicks or graduations on your measure for each group. This is where keeping good notes comes in handy. When you find the group with the least vertical dispersion. 
  Now its time to go to five shot groups start with the setting that gave you the best vertical dispersion. Take off a click shoot a couple of five shot groups. Move up a click and do the same thing then move up another click and do it again. Do the same thing over several sessions, as some powders will give you different results under higher or lower temperatures. Again what you are looking for is the best vertical dispersion you can get. The left and right is wind that is about learning to read the wind and that is a separate issue. You will find that as you learn to read the wind your groups will get tighter all the way around. 
  At any rate when you have a good speed record it. As John points out you can use it as a reference point when you get a different lot of powder or when you switch powders.

40 Rod
  
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JLouis
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Re: Chronograph use help needed
Reply #6 - Oct 2nd, 2013 at 12:47pm
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Don't take to much merit in low ES's and SD's, in theory they should provide the best results at the target but seldom does that always hold true for reasons unknown to me? I tend to ignore them as I don't want them to be a guiding factor, when I find the best results at the target I will make note of them and if they just happen to be low it's a little added bonus. On the other hand if they are a little high of which has been more typical for me I still stick with what the target is telling me. I might also add that they are not a constant and can be low today and high tomorrow depending on the density altitude for the day of which both are in a constant mode of change as the day goes by.

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boats
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Re: Chronograph use help needed
Reply #7 - Oct 2nd, 2013 at 9:21pm
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Nice to know velocity, not required if using standard Schuetzen loads. Results on target are much better indicators.  Most of my loads have been over a crono once or twice just to confirm working velocity. Never used it to develop optimal loads.

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Re: Chronograph use help needed
Reply #8 - Oct 2nd, 2013 at 9:28pm
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Agree with the extent of it's usefulness, Boats.  But I do find it interesting to note that two of the times I met Bill Alexander (Alexander Arms) he was at the range taking meticulous notes on powder charge/bullet, velocity, accuracy and chamber pressure when he was working up loads for the 50 Beowulf.

Is there a correlation between accuracy and velocity?  Perhaps not.  Are there GOOD velocities for good accuracy (with certain powder/bullet combinations)?  I think yes.

  

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Re: Chronograph use help needed
Reply #9 - Oct 3rd, 2013 at 6:33am
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Cat I think he is doing the right thing if looking for the last word in testing.  Do you need to in order to work up successful loads, I don't think so. As a sport itself testing is a good one and probably the real reason for running over the Crono

Boats
  
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40_Rod
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Re: Chronograph use help needed
Reply #10 - Oct 3rd, 2013 at 8:27am
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John
Note I recommended the use of the chronograph only to fine tune your load and measure technique. Low SDs are important but only for shot to shot consistency. However if your velocity is not optimal for your bullet / twist combination then shot to shot consistence is meaningless. Low SDs are important just as shooting bullets that weigh the same is important. 

40 Rod
  
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Re: Chronograph use help needed
Reply #11 - Oct 3rd, 2013 at 3:29pm
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boats wrote on Oct 3rd, 2013 at 6:33am:
Cat I think he is doing the right thing if looking for the last word in testing.  Do you need to in order to work up successful loads, I don't think so. As a sport itself testing is a good one and probably the real reason for running over the Crono

Boats


We are in agreement.
  

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Re: Chronograph use help needed
Reply #12 - Oct 3rd, 2013 at 4:24pm
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40 Rod I don't think we are in disagreement, striving for low SD's & ES's is as critical as the quality and  choice of the correct bullet but at times the target tends to be in disagreement. I think once you have the bullet at it's most efficient point in it's flight all things that need to be considered finally come together. At this point in time I have found the SD's & ES's will naturally evolve to where they need to be. Getting there to me is the fun part and it takes allot of time and effort to go through all of the possible combinations to get it there. During this process I don't like to have any pre conceived notions guiding me in a given direction. 

I hope that makes some sort of sense?
JLouis
  

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Re: Chronograph use help needed
Reply #13 - Oct 5th, 2013 at 3:12am
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I only use the chrone once I have an accurate load for my BPCR rifles.  This is to check whether the load will hold up at longer ranges.  A high ES being something to avoid, even though the load might be pretty accurate at shorter ranges.
  
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Re: Chronograph use help needed
Reply #14 - Oct 5th, 2013 at 11:58am
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If you are a black powder shooter the chronograph is a useful tool to measure the effectiveness of your fouling management routine.   

Chris.
  
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