Why test velocity on target guns?

[C-130 Dude]

It occurs to me that the most important thing when target shooting is accuracy, not velocity.

We know that most guns will achieve maximum accuracy when using cartridges charged with something less than maximum powder charge.

If this is the case, does velocity matter?

Is testing velocity necessary for prediction of accuracy?

 

[338 dude]

It occurs to me that the most important thing when target shooting is accuracy, not velocity.

We know that most guns will achieve maximum accuracy when using cartridges charged with something less than maximum powder charge. If this is the case, does velocity matter?

I would say it matters to make sure you're in the node and at the velocity you intended to be,also to track velocity under different weather conditions.

 

[lancetkenyon]

Maybe actual velocity might matter less, but charting ES and SD can certainly make a difference at extended ranges. Maybe not so much at 100 yards, but at 1000, it does. Also, TOF can have an impact in the winds at extended ranges. So higher velocity can cut differences in drift variations in fluctuating winds. Especially if you don't know wind speeds.

 

[C-130 Dude]

Maybe actual velocity might matter less, but charting ES and SD can certainly make a difference at extended ranges. Maybe not so much at 100 yards, but at 1000, it does. Also, TOF can have an impact in the winds at extended ranges. So higher velocity can cut differences in drift variations in fluctuating winds. Especially if you don't know wind speeds.

Good points. All. Just curious what the net effect would be when setting up a new gun at 100yds.

 

[del2les]

Maybe actual velocity might matter less, but charting ES and SD can certainly make a difference at extended ranges. Maybe not so much at 100 yards, but at 1000, it does. Also, TOF can have an impact in the winds at extended ranges. So higher velocity can cut differences in drift variations in fluctuating winds. Especially if you don't know wind speeds.

Yes. Just run the drift and drop calcs for a 1,000yd BR or F-class load that has high ES and SD. Say 50-75 fps, and then you'll see a good group or score turn into an also ran. Even the 600yd prone scores in Nat'l Match or F-class can go from X's or 10's to 9's or worse.

I.e. My 223 80gr AMAX load at 2,900fps with 300yd zero has a 242" drop at 1,000yd, but if the load is 2,850fps, that same bullet now drops 252" at 1,000. A 10" difference and a disaster to the group and score.

 

[C-130 Dude]

Yes. Just run the drift and drop calcs for a 1,000yd BR or F-class load that has high ES and SD. Say 50-75 fps, and then you'll see a good group or score turn into an also ran. Even the 600yd prone scores in Nat'l Match or F-class can go from X's or 10's to 9's or worse.

Thanks.

 

[DoneNOut]

Shoot Viht powders. They will never wow factor you with velocity, but they will show some very accurate loads here and there.

 

[Coyote Shadow Tracker]

Good points. All. Just curious what the net effect would be when setting up a new gun at 100yds.

I think that it is two different things.
When working up a load at 100 yds I always look for the most accurate load with low ES & SD and not looking for the fastest load.
Some shooters will look for an acceptable group MOA and pump the load for highest velocity.

At 100yds doesn't matter if just hunting at that range.
FPS matters with wind drift and Drop, Gravity is constant but the farther an object can travel in a specific amount of time relative to gravity will give you more or less drop.
If you are shooting distance YES VELOCITY MATTERS.
BC also comes into play. That is different with bringing DRAG into the discussion.

 

[C-130 Dude]

Shoot Viht powders. They will never wow factor you with velocity, but they will show some very accurate loads here and there.

Have n140 and n150 on hand. Currently using I4064 for breaking and starting load development. And the search begins......

 

[del2les]

Good points. All. Just curious what the net effect would be when setting up a new gun at 100yds.

At 100yds, things are more forgiving, and here a higher ES and SD may not show much difference than a load with very low. I have shot some very good 100yd BR groups with loads that had high variations, and if it wasn't for the proof on paper, I would have never accepted those loads for BR.

 

[C-130 Dude]

At 100yds, things are more forgiving, and here a higher ES and SD may not show much difference than a load with very low. I have shot some very good 100yd BR groups with loads that had high variations, and if it wasn't for the proof on paper, I would have never accepted those loads for BR.

So you saying at closer range, 100yds, you may get good accuracy but have iffy es and sd?

 

[del2les]

So you saying at closer range, 100yds, you may get good accuracy but have iffy es and sd?

Yes, but those SR groups can be a little deceiving and will show themselves when pushed to LR.

 

[C-130 Dude]

Yes, but those SR groups can be a little deceiving and will show themselves when pushed to LR.

Gotta start somewhere. I'll keep what you said in mind going forward.

 

[hankle]

Boy was I cocky when I when I started reloading. I had a chrono, but it was finicky and I quit using it because was getting tiny groups at 100yds. I finally got access to 1000yds and wandered what happened to my tiny groups. I started chrono-ing and found I had SD issues. A well tested load with low SD may actually be more accurate at distance than a load with a smaller group at 100yds. That vertical stringing and cost to BC really matter.

Best of luck!
HW