Questions about velocity data

[Banshee]

I am a new reloader and ran into something unexpected yesterday at the range while using my chrony for the first time with rifle loads instead of for shotgun loads.

Load
270 WSM with winchester brass and CCI 250 primer
110 gr Barnes TTSX
MagPro powder

Gun
Savage 11 FCNS with 24" barrel 1 in 11" twist

Charge Vel1 Vel2 Vel3
75 3410 3376 3398
76 3427 3416 3410
77 3462 3468 3468
78 3492 3521 3480
79 3557 3547 3557

The velocity at 77 gr and 79 gr are very consistent while the others varied quite a lot. Is this something normal or not? The groups for these two charges were very similar but not the best of the tested rounds.

all charges were hand weighed, all rounds loaded during the same session, all lengths were the same. No pressure signs noted.

In shotshells, consistent velocity round to round nearly always lead to a very good load, does that hold true for rifles as well?

Banshee

 

[JD338]

The chronograph is reporting what loads are efficient. You will see variations in loads. Pick the one that has the lowest ES and SD and work with that load. By changing the seating depth, you should be able to fine tune for accuracy. IMHO, accuracy is king and velocity is second.

JD338

 

[DrMike]

JD has given excellent advice. Velocity does not kill game, shot placement does.

Actually, your SD for the data you report looks pretty good. Anything less than 1% should allow playing with seating depth Moreover, the velocity differential between 75 grains and 79 grains is only about 150 fps, which is not very significant in the field. However, bear in mind that it is possible to get aberrations with small sample sizes--i.e., small SD when the load is in fact quite poor or exaggerated SD when in fact the load may be very good. You cannot know with any degree of certainty what the SD is with anything less than 10 rounds. However, if you shoot a load several times, with a sample of three rounds, and the data is consistent, you can have a high degree of confidence about the load.

It really sounds as if you have good technique at the reloading bench, which means that you should get some great results as you continue metallic cartridge reloading.

 

[Antelope_Sniper]

As the doctor and JD were saying 3 rounds is a small sample size. Sometimes I'll do my "run up" with strings of 2 (typically reserved for pressure checks) or 3 until I get a feel for a particular combination. I like strings of 5 for my more serious work, but the pro's recommend 10. I'll let them shoot 10, I'd rather not shoot out my barrel before I've found my load. In some rifle's the faster you shoot the more accurate it shoots. Other will like a more moderate load. Listen to your rifle, and it will be hard to go wrong.