Newbie questions about chrono numbers

romad97

Well-Known Member
Joined
Apr 21, 2012
Messages
187
After a year of reloading I finally broke down and bought a chrono. I purchased the new magnetospeed sporter. I went out today and shot a few rounds to gather some data but, I don't really know whether my numbers are good or bad. I am reloading for a 25-06. I am shooting a Tikka T3 lite which has a 22 inch barrel. I am using winchester brass, WLR primer, 52 gr IMR 4831, 100 gr barnes TTSX with a COAL of 3.13 which is .080 off the lands. I can typically get 1 to .75 MOA with this load. Today I finally got to chrono my load and this is what I got. First 4 shots were definaltely low. I am not sure if this is becouse I was shooting a clean cold bore or what but, they were as follows.

1. 3013
2. 3033
3. 3067
4. 3098

My next string of shots seemed to actually be a little better.

5. 3098
6. 3043
7. 3063
8. 3130
9. 3100
10. 3144
11. 3116
12. 3092
13. 3128
14. 3121
15. 3065
16. 3108
17. 3113
18. 3095
19. 3096
20. 3127

I disregarded the first 5 shots as they were from a clean cold bore and I came up with the following numbers. An ES of 101 fps, Avg 3110 fps, and an SD of 33 fps. I am not sure if these numbers are considered good, marginal or bad.
 

phorwath

Well-Known Member
Joined
Apr 4, 2005
Messages
6,608
Location
Alaska
ES of 101 and SD of 33 is what most would consider poor. I'd like to have ES less than 25-30fps for long range hunting or target practice. Ideally less than 15-20fps.

If your rilfe shoots decent groups and you don't shoot farther than 600yds you may be good/happy with what you've currently got.
 

Corey Schwanz

Well-Known Member
Joined
Nov 10, 2014
Messages
191
Location
Indiana
I would definitely want to try to tighten those up quite a bit. 100+ ES is a lot. Are you weighing powder charges individually or just throwing them with a powder dispenser? Doing any bullet sorting or case prep to the brass?

The key thing to think about is consistency. You want as many variables as you can control to be as close to identical as you can get them. Bullet weight, seating depth, primer pockets, powder charges, etc.
 
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