While this is certainly a "range report", the real purpose of shooting the 8mm SLT was to make sure it was "on" so I could shoot at a 6" target at 300 yd per this thread: https://www.forum.thehunterslife.com/index.php?topic=16867

Here's the target at 100 yd:


(Oops. Second an third are backwards. The on-target notations are correct.) First shot cold barrel, then the other two touching. First one is about an inch and a quarter from the second and third. These are the 220 Sierra BTSP. The bullet that shoots the straightest from this rifle. The MVs are: 2630, 2634, 2638. The average is 2634 f/s. Max spread of 8 f/s is pretty good. I'm fine with the 3-shot group. I like this load, therefore I was not particularly interested in shooting any more. I know where they are 'going'. I was saving the ammo for the 300 yd shoot.

However, I did want to shoot the new 136-grain swaged bullets and see how they did in the LONG throated Steyr LONG Throat.

2 and a half inches high and 5 and a quarter inches wide is hardly encouraging. However, it is in the LONG throated chamber. I just didn't expect THIS bad. MVs were: 3594, 3533, 3566 for an average of 3564 f/s. The spread of 61 f/s isn't exactly 'good', but... MVs of the mid 35s is 'good'.

Paul

Here's my statistical analysis of the groups produced by shooting these two bullets. First the 220 Sierra bullets:


Then the swaged 136 grainers:


Of primary interest to me is the value for the Area of the 95% Confidence Ellipse seen in cell "F16". For the 3-shot 220 Sierra group, that value is 7.34 square inches; for the factory group it is about 101 square inches. For the 220 Sierra, that would be a rectangle about 2.25" wide by about 4" high. (Or more precisely, an ellipse with x-axis length of 2.26" by y-axis length of 4.14".) What that values predicts is the area into which I could expect the next 95 out of 100 shots to go at 100 yd. The combination of large group AND SMALL SAMPLE SIZE - only 3 shots - means that my 'confidence' in predicting where the next 95 out of 100 shots will go - BASED ON THIS SAMPLE - is very low.

If you look at cell "B3" you will see the value of "Student's t". That value is based on the sample size. The larger the sample size, the smaller the Student's t value. The Student's t value is a MULTIPLIER of the variance observed in the shot string. Therefore, the greater the number of shots you are using to determine the parameters (average, variance, etc.) the better the estimate of 'reality' you will have. Since the smaller the sample size the less confidence one has that the samples used actually REPRESENT REALITY, you have to broaden the PREDICTED parameter.

Taking "max spread" as an indicator of THE BOUNDARIES AROUND where the "next bullet" is going to hit is "optimistic" at best. Put another way, it's fooling yourself. There are PLENTY of people in the world that want to fool me, I don't need to fool myself. What I want to know is my BEST GUESS at where the 'next' bullet is going to hit based on where the last "X number" of them hit. Max spread is "easy", but it's not "good" for making that prediction/guess.

Paul

PS - If you have MicroSoft Excel and would like a copy of the spreadsheet so you could perform your own calculations, shoot me a PM and I'll email a copy with some instructions to you .

Paul