This is not black and white, noob post

[Seismic Sam]

Interesting - it WAS the chrono after all - Whoodathunkit?? Not sure what the difference in force is between tapping and muzzle blast, but it can't be all that dissimilar. Especially since your 9mm was reading fine and your 45 data was consistently wonky. How far from the muzzle was the rear screen of the chrono? I typically put mine out 8' or so, and for my Smith 500 it's more like 12' - 14'. If you move the chrono in to 6' for a Smith 500, you have to attach small, sharp pins to the support arms for the skyscreens. Those have to be there to hold the marshmallows so you can make smores while you are shooting!!!

[MarkL]

Certainly appears to be the chrono. I got the replacement sensor in yesterday and I cannot duplicate tapping the screen or sensor to trigger an error.
I've kept the chrono about 10' from the muzzle/bench so that distance should be good. I will be headed back out to BGC again Saturday morning to refire and see what happens. I'm really hoping to see some solid results. I will test with factory 9mm, 45acp and reloads for 45 with 4.5 and 4.8gr's.

[MarkL]

Looks like everything now is as it should be. Chrono registered expected data for factory and my reloads. Shot factory 45 and 9mm for a baseline.
Looks like I can step the 45 up to 5.0gr and give that a go.

String 1 - Federal American Eagle 45acp
1) 831.5 -4.4
2) 855.6 19.7
3) 838.1 2.2
4) 815.2 -20.7
5) 839.2 3.3

High: 855.6
Low: 815.2
E.S.: 40.4
Ave.: 835.9
S.D.: 13.1
95%: ±20.3

String 2 4.5gr Bullseye 230gr Berry's plated HBRN, Win LPP
1) 699.4 -33.5 f
2) 759.9 27.0
3) 728.8 -4.1
4) 741.3 8.4
5) 728.3 -4.6
6) 731.6 -1.3
7) 737.6 4.7
8) 738.2 5.3
9) 730.9 -2.0
10) 732.5 -0.4

High: 759.9
Low: 699.4
E.S.: 60.5
Ave.: 732.9
S.D.: 14.2
95%: ±11.3

String 3 4.8gr Bullseye 230gr Berry's plated HBRN, Win LPP
1) 752.2 -13.7
2) 760.4 -5.5
3) 763.9 -2.0
4) 762.6 -3.3
5) 759.8 -6.1
6) 762.4 -3.5
7) 773.0 7.1
8) 795.2 29.3 f
9) 763.6 -2.3

High: 795.2
Low: 752.2
E.S.: 43.0
Ave.: 765.9
S.D.: 11.5
95%: ±9.9

9mm Remington UMC
1) 1076.0 -16.3
2) 1068.0 -24.3
3) 1049.0 -43.3
4) 1047.0 -45.3
5) 1062.0 -30.3
6) 1048.0 -44.3
7) 1106.0 13.7
8) 1128.0 35.7
9) 1131.0 38.7
10) 1130.0 37.7
11) 1128.0 35.7
12) 1134.0 41.7

High: 1134.0
Low: 1047.0
E.S.: 87.0
Ave.: 1092.3
S.D.: 35.4
95%: ±24.6