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LeeB
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Hello Steel Challenge PCC Shooters (with some IDPA applications)
Since I now have way too much time on my hands due to the stay at home order, I have embarked on a ballistics investigation and proper zero distance for my PCC. The distance I have arrived at is 13.5 yards. Now, I’ll tell you how I arrived at that distance which might spark some interest and discussion from others on their ideas.
First, I am no expert in shooting steel or ballistics. Second, I shoot a Diamondback DB9R with a 16 inch barrel, 9MM Blazer CCI 115 grain FMJ ammo with a muzzle velocity of ~1300 fps and a Vortex Strikefire II red/green dot optic sight. I am tall and lanky so my optic uses the factory cantilever mount and a 1 inch riser, resulting in a very large 3.6 inch offset. Until I understood how offsets affect bullet travel (thanks to the more expert people shooting around me) I always shot low on short distance targets. Therefore, I wanted to know my bullet trajectory to try and shoot more accurately so I undertook this examination as all the required information is readily available.
Step one was to download all 8 steel challenge stage schematics. Step two was to calculate all target distances. This required a bit of math as some targets are straight ahead of the shooting box while most are at angles. However, all the angle targets create right triangles from the shooting box so simple use of the Pythagorean Theorem (A2 + B2 = C2) quickly determines the length of the hypotenuse, or angle distance to the target. These were rounded to the nearest single decimal place. Step three was to create an Excel spreadsheet (attached) of all stage targets and distances. Since there are only 8 stages and 5 targets per stage, this resulted in 40 total targets grouped by similar distance from 7 to 35 yards.
Approximate values are:
5 at 78
11 at 10
2 at 12
7 at 15
5 at 18
4 at 20
2 at 25
4 at 35
Now I made a few executive decisions here. Since I have never been to a competition that included the Outer Limits stage, I deleted it which left only 35 targets. Of these, Showdown has 2 targets at 25 yards and Accelerator has 1 target at 21 yards. However, these 3 are all large (18x24) rectangle targets so I deleted them. That left only 31 targets, all between a short 7 and a long 20 yards. The difference between the short and long is 13 yards, ½ of 13 is 6.5. Add 6.5 to 7 or subtract 6.5 from 20 and you get the same distance, 13.5 yards.
I chose 13.5 as half way between short and long to have minimal change in my sight point. I’m sure there are many other ways to solve this problem. After bench rezeroing my PCC at 13.5 yards, I then took shots at 7.5 (only one target at 7) and 20 yards which resulted in my bullet striking ~1.5 inch low at 7.5 and 1.5 inch high at 20. Since the smallest target in steel is 8 inches in diameter, I can sight almost 90% of the target and get a hit. I created a visual trajectory graph in PowerPoint (attached) to keep in my bag as a reminder of the bullet path (helps with IDPA targets too).
Finally, I downloaded a free Hornady ballistics app which asks for all the parameters of your PCC and ammo that I gave above then calculates trajectories at any distance, in as low as 1 yard increments. The numbers were almost identical to my range day.
I’d be interested to hear what others have done and why.
Since I now have way too much time on my hands due to the stay at home order, I have embarked on a ballistics investigation and proper zero distance for my PCC. The distance I have arrived at is 13.5 yards. Now, I’ll tell you how I arrived at that distance which might spark some interest and discussion from others on their ideas.
First, I am no expert in shooting steel or ballistics. Second, I shoot a Diamondback DB9R with a 16 inch barrel, 9MM Blazer CCI 115 grain FMJ ammo with a muzzle velocity of ~1300 fps and a Vortex Strikefire II red/green dot optic sight. I am tall and lanky so my optic uses the factory cantilever mount and a 1 inch riser, resulting in a very large 3.6 inch offset. Until I understood how offsets affect bullet travel (thanks to the more expert people shooting around me) I always shot low on short distance targets. Therefore, I wanted to know my bullet trajectory to try and shoot more accurately so I undertook this examination as all the required information is readily available.
Step one was to download all 8 steel challenge stage schematics. Step two was to calculate all target distances. This required a bit of math as some targets are straight ahead of the shooting box while most are at angles. However, all the angle targets create right triangles from the shooting box so simple use of the Pythagorean Theorem (A2 + B2 = C2) quickly determines the length of the hypotenuse, or angle distance to the target. These were rounded to the nearest single decimal place. Step three was to create an Excel spreadsheet (attached) of all stage targets and distances. Since there are only 8 stages and 5 targets per stage, this resulted in 40 total targets grouped by similar distance from 7 to 35 yards.
Approximate values are:
5 at 78
11 at 10
2 at 12
7 at 15
5 at 18
4 at 20
2 at 25
4 at 35
Now I made a few executive decisions here. Since I have never been to a competition that included the Outer Limits stage, I deleted it which left only 35 targets. Of these, Showdown has 2 targets at 25 yards and Accelerator has 1 target at 21 yards. However, these 3 are all large (18x24) rectangle targets so I deleted them. That left only 31 targets, all between a short 7 and a long 20 yards. The difference between the short and long is 13 yards, ½ of 13 is 6.5. Add 6.5 to 7 or subtract 6.5 from 20 and you get the same distance, 13.5 yards.
I chose 13.5 as half way between short and long to have minimal change in my sight point. I’m sure there are many other ways to solve this problem. After bench rezeroing my PCC at 13.5 yards, I then took shots at 7.5 (only one target at 7) and 20 yards which resulted in my bullet striking ~1.5 inch low at 7.5 and 1.5 inch high at 20. Since the smallest target in steel is 8 inches in diameter, I can sight almost 90% of the target and get a hit. I created a visual trajectory graph in PowerPoint (attached) to keep in my bag as a reminder of the bullet path (helps with IDPA targets too).
Finally, I downloaded a free Hornady ballistics app which asks for all the parameters of your PCC and ammo that I gave above then calculates trajectories at any distance, in as low as 1 yard increments. The numbers were almost identical to my range day.
I’d be interested to hear what others have done and why.
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