Velocity and holes on paper

[Wolfdog91]

So this may be a dumb question but just how much can velocity change a bullets flight path and where it will end up on paper ? Just playing around today shooting groups with a load and while shooting over the Chrono I kinda noticed round going so fast seemed to go to one place on the paper and rounds going so fast went another place. Figured it was just me but I went change the powder weight a little just to see what would happen. And I go this


So say I saw able to snap may finger and magically make five rounds that shot 2960 fps- 2980 fps and five rounds that shot 2850-2890 fps and I shot them at another target same zero. Would they group in generally the same areas ?
Is this a common thing ?
I remember when shooting my non regulated PCP air gun after it drops below say 2000PSI my velocity drops and certain pellets and would group different at the slower ( or higher if I kept if filled ) speeds.
Sorry is this is a stupid question lol just curious what the pros think.

 

[Straightshooter1]

It's certainly NOT a dumb question. And yes . . . it's a common thing. It has to do with barrel harmonics and the "barrel time", which is a function of velocity. So, finding the anti-node of your barrel harmonics with the right velocity along having that velocity consistent as possible should produce good accuracy and precision where they're ending up in the same area. . . .

. . . .preferably in the same hole.

 

[Ccrider]

The true question is why are you getting variation in speed if your loads are the same. Until you get your loading process down to acceptable consistency, it is hard to say what impact speed has on point of impact.

Work your load up, increasing the powder charge only on increments. You will then see the impact of velocity on the load. If everything else is close to right, you will see the load go in and out of tune in paper. Also, the lowest es will not necessarily be the best tune.

Last, I have had ppc loads different by 100fps go into the same hole at 100yds. The longer the distance, the more variances in es generally impact the group.

 

[Pawnee Bill]

It's all in the harmonics.

 

[357Mag]

So this may be a dumb question but just how much can velocity change a bullets flight path and where it will end up on paper ? Just playing around today shooting groups with a load and while shooting over the Chrono I kinda noticed round going so fast seemed to go to one place on the paper and rounds going so fast went another place. Figured it was just me but I went change the powder weight a little just to see what would happen. And I go this
View attachment 1381596

So say I saw able to snap may finger and magically make five rounds that shot 2960 fps- 2980 fps and five rounds that shot 2850-2890 fps and I shot them at another target same zero. Would they group in generally the same areas ?
Is this a common thing ?
I remember when shooting my non regulated PCP air gun after it drops below say 2000PSI my velocity drops and certain pellets and would group different at the slower ( or higher if I kept if filled ) speeds.
Sorry is this is a stupid question lol just curious what the pros think.

Wolf -

Howdy !

You can use one of the external ballistics calculators that they have on-line, to plug N' play.....using your own input information ( calibre, bullet wt; vel etc ).

Change input conditions like veloocity in small increments, and see what happens to the trajectory.


With regards,
357Mag

 

[Bronsin]

When I use 40gr bullets in the .223, I get 117fpd ES because the bullet is completely out of the case before it gets into the rifling. How much pressure escapes around the bullet before it seals off the bore is anybodies guess, but I'm sure that affects the velocity by a bunch. 50gr bullets don't do that.