Help with Chronograph results

[ThomasT]

Hello everyone,

I just shot 3 different pellets in the Crown MK II , and as you can see in the chart the only change to the rifle settings was on the last round where I lowered the Hammer Spring setting from 16 down to 14. I shot 10-rounds with each set and all conditions exactly the same and used a new ProChrono for the test. I did not shoot at a target so I cannot compare any impact information. I am just trying out the new Chrony and would appreciate any interpretation that anyone can share with me. 

Be safe and have a great day,
ThomasT

View attachment Chronograph Results 2022x1.1653397431.bmp

 

[Kgphotos]

The chrony results look normal to me. You dropped hammer spring at the end and saw a drop in velocity which is what you would expect. When shooting the slugs there was a drop in velocity which is also expected. Slugs have much more bearing surface than pellets do and therefore will shoot at a slower velocity all else being equal. Everything in your chrony results looks as I would expect. Am I missing something? 

Kenny

 

[nervoustrig]

A few observations:

1. It is producing in the vicinity of 18 – 19fpe with the hammer spring on 16. Somewhat less on the 14 setting which means the baseline hammer spring tension is not too high. That is, the wheel functions to reduce power but may or may not be capable of taking it up to maximum power. If you want to know, either follow the directions in the next step _or_ put the wheel on max and record a string until the velocity has clearly tapered off. If it tapers off neatly, the hammer spring tension is fine. If instead there is a hump before the velocity begins to fall, the baseline hammer spring tension needs to be increased (or reduce the regulator’s setpoint).

2. Extreme spread is decent but probably not optimal. If you want to set it to a state of tune where the velocity is most consistent, gradually increase the hammer spring tension until the velocity no longer increases, then back off the tension until the velocity falls to somewhere between 95 – 97% of that maximum. On the Crown, changing the baseline hammer spring tension is done via a grub screw accessible under the power wheel. Increase its projection to increase hammer spring tension.

3. Slugs are achieving a velocity somewhat less than the equivalent weight pellet, which is generally expected (bore friction and possible blow-by). However at a modest distance, the pellet will have lost enough velocity to fall behind the slug.

 

[ThomasT]

The chrony results look normal to me. You dropped hammer spring at the end and saw a drop in velocity which is what you would expect. When shooting the slugs there was a drop in velocity which is also expected. Slugs have much more bearing surface than pellets do and therefore will shoot at a slower velocity all else being equal. Everything in your chrony results looks as I would expect. Am I missing something? 

Kenny

Hello Kenny,

No you aren't missing anything from my question, this is the first time that I have used a Chrony and just trying to learn from the results. I "assumed" that the results were normal but I am glad that you confirmed this to me. Now as I compare more Chrony results with more pellets I will be able to create a chart to study. I don't want to get paralysis by analysis but I would like to maybe understand some of the information a bit better.

Thank you for your help and have a great day,

ThomasT

 

[ThomasT]

A few observations:

1. It is producing in the vicinity of 18 – 19fpe with the hammer spring on 16. Somewhat less on the 14 setting which means the baseline hammer spring tension is not too high. That is, the wheel functions to reduce power but may or may not be capable of taking it up to maximum power. If you want to know, either follow the directions in the next step _or_ put the wheel on max and record a string until the velocity has clearly tapered off. If it tapers off neatly, the hammer spring tension is fine. If instead there is a hump before the velocity begins to fall, the baseline hammer spring tension needs to be increased (or reduce the regulator’s setpoint).

2. Extreme spread is decent but probably not optimal. If you want to set it to a state of tune where the velocity is most consistent, gradually increase the hammer spring tension until the velocity no longer increases, then back off the tension until the velocity falls to somewhere between 95 – 97% of that maximum. On the Crown, changing the baseline hammer spring tension is done via a grub screw accessible under the power wheel. Increase its projection to increase hammer spring tension.

3. Slugs are achieving a velocity somewhat less than the equivalent weight pellet, which is generally expected (bore friction and possible blow-by). However at a modest distance, the pellet will have lost enough velocity to fall behind the slug.

Hello nervoustrig

OK, I will try this as you have stated, this will be a good learning experience for me with this rifle. I really appreciate this help from you.

Be safe and have a great day,

ThomasT