Faster bullets vs heavy bullets for wind drift

[roob]

Hi all,

Question for the target shooters here on bullet weights and how well they handle the wind.

I get that a heavier bullet as a general rule is less affected by wind than a lighter bullet, right?

A lighter bullet you can shoot faster though, and so at a higher velocity there is less time for it to be affected by wind. (A lighter bullet will have less recoil too of course which is a plus.)

Obviously exact weight vs speed can change the answer to this depending on the load, but as a general rule which do you think is best for ignoring the wind.

Say a 200gr 30 cal vs a 150gr which you can launch quite a lot faster.

Cheers.

[Chronos]

Your best bet might be to try one of the online ballistic calculators and answer the question yourself. Short answer is I don't know but I could work it out for you if you want. I have a couple of ballistic apps in my phone that will give me wind drift

Chronos

[Chronos]

Best I can see with a quick look the difference in wind drift at 500y between a 150gr factory loaded hpbt and a 220gr in a 10mph wind would be around 1" (11" for the 150gr and 12" for the 220gr)

So yes, the light bullet gets there quicker and so is less affected by wind but this is oversimplified a little.

Chronos

[Manimal]

Only an observation here, but the all the guys I see shooting top accuracy are using heavy pills.

Reading wherever on the loads people have tested, I think everyone tries lighter loads for accuracy and recoil, but they seem to end up going back to the heavy stuff sooner or later.

Not exactly scientific but there it is

[Apollo]

In my opinion there is a bit more than bullet weight and velocity that affect the accuracy of bullets used for target shooting. Bullet design / shape has a pretty good influence so you can have a light and/or heavy bullet travelling at the same speed but different in design and will have different effects from wind drift.

Some calibres have been proven by size/design of their cartridge case to prefer a certain bullet weight for accuracy over velocity and/or weight.

One very good source I use to look at ballistics is JBM and their ballistics calculator gives you some very good information that so far I have found to be very close to real life testing. Lots of input required but if you give it the correct information you get a prety good output to use.

http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi

Lots of other calculators and information available on the site.

[Apollo]

One example of a calibre preferring a certain weight bullet is the 6.5x47 Lapua.

Some target shooters try and use bullets in the 140gr weight range and even though they can be pushed as quick as a slightly lighter bullet they don't provide the same consistancy of accuracy.

The 140gr and 130gr Berger VLD Target Bullets are very close to the same dimensions only 10gr different in weight. This cartridge performs way better using the 130gr bullet. Chamber designs like Free Bore length are usually the same for either.

Great results can be had with the lighter 123gr like 123gr Lapua Scenar but the chamber design is different and this applies to a lot of calibres which need a change of design to use different bullet weights.

[Chronos]

But we are talking about wind drift not accuracy are we not?

Chronos

[Apollo]

Don't they go hand in hand.

Anyway, you can have a number of bullets all the same weight but different design and they will be affected by wind drift in different ways even though they have the same velocity.

A thought. A lighter bullet travelling at a higher velocity gets to it's target quicker than a heavier slower one. The lighter bullet is affected by the wind for less time in it's travel.

[Chronos]

A thought. A lighter bullet travelling at a higher velocity gets to it's target quicker than a heavier slower one. The lighter bullet is affected by the wind for less time in it's travel.

? That's the topic.

From the opening post.

"A lighter bullet you can shoot faster though, and so at a higher velocity there is less time for it to be affected by wind"

[Hercl]

Somebody's not quite awake yet

[Lorgar]

Try this on for size Roob - 155gr vs 175gr Barnes Match BT bullets, velocity is based on ADI max powder charge data using AR2208.

Be sure to click the image to see the full table out to 1,500m.

.308 wind drift trajectory

308-wind-drift-trajectory.gif (15.09 KiB) Viewed 6058 times

In this example the heavier bullet has the edge across the entire range, as a general rule though distance is going to be your decider.

As you can see in the table; despite starting off faster, due to the lower BC of the lighter bullet it's eventually going slower than its heavier competitor and any advantage gained by speed is lost. As the speed washes off the gap closes until the lighter bullet becomes disadvantaged.

At shorter distances, a different comparison will probably yield different results. e.g. if you compared a much lighter, much faster bullet to the heavier one, I expect the lighter bullet will have the advantage like Chronos' example outlined.

At longer ranges though the heavier bullet will always have the advantage.

If you're shooting inside 400m you might as well shoot the lighter bullets and not have to put up with the recoil. If you're shooting further and want every possible advantage shoot heavier bullets.

Velocity is temporary, ballistic coefficient if forever

[Norton]

My brains not working, when you said "Try this on for size Roob" I missed OP's name and thought you were having a go at Chronos for saying something wrong

I need some sleep.

[Lorgar]

Ha ha.

No, not having a go at anyone