Affects of bullet grain wt.

[jds247]

I'm not as smart as these guys. I ran into the ammo shortage problem with my youngest sons deer rifle. I took the 2 different bullets to the range and shot them both.. there was only 20 grains different. And impact difference was minimal.

I'd just shoot both and see if it's good enough to hunt with.

[bmac]

I’ve had bullets shoot little groups and different widget bullets shoot pie plates. Not saying won’t do it’s job at 100 yards, but I would test shoot 1 before I went hunting. No point of wounding something for a quick check item.


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[glen]

Go shoot a 3 shot group. Decide if you are going to shoot that round. Then go shoot it at your comfortable hunting distances and write on a piece of paper. Laminate paper and tape to stock.

[WhiplashTX]

Gravity acts the same for a bullet weighing 100 gr as it does for a bullet weighing 200 gr.

This. ^

The only thing that determines actual bullet drop is time of flight. FPS, BC, temp, ect are all things that affect the flight time.

In theory the 180 would be hitting lower than the 150 since it should be moving slower and 100 yards isn't enough distance for the 180's possibly higher BC to make a difference. Harmonics will affect the distance between the two bullets impacts also and more than likely make a shift to the right or left. As you the OP concluded himself, the only way to know for sure is to shoot them.

[Rubberdown]

I’m plugged a few things in my ballistics app. I used a 30/30 because the aerodynamics suck and drops pretty quick to prove the point.

Using a 30/30 150 grain... at 100yd the drop is .0066.
Using a 30/30 180 grain... at 10”yd the drop is .0112.

At a 100 the bullet has barely started to drop. Now if you reach out to 200

Using a 30/30 150 grain... at 200yd the drop is 7.1273
Using a 30/30 180 grain... at 200yd the drop is 8.4436

It’s all downhill from there. Gap opens up the further you get out.

[Rubberdown]

I guess I should state before someone gets mad at my math I used winchesters states barrel velocities for each round. The heavier the bullet the slower it goes.

[bboswell]

Affects of bullet grain wt.

Some of you math and science whiz’s need to learn the difference between trajectory and point of impact.

Given the 100yard point of impact then the math works but there is no predicting how POI will shift when switching from one bullet to another no matter the weight.

[rfroese]

Some of you math and science whiz’s need to learn the difference between trajectory and point of impact.

Given the 100yard point of impact then the math works but there is no predicting how POI will shift when switching from one bullet to another no matter the weight.

Yep. Problem is that in the hunting community, people tend to just take people's word as facts often times without understanding the truth. Especially when it comes to guns. Learning to reload ammo and beginning to understand ballistics changed so many of the ideas I had about firearms.


Can't even begin to tell you how many "myths" I grew up hearing as facts that have been dispelled as I have gotten older.

To the OP, there is no way to know without shooting the other ammo. Theoretically, the bullet should drop more from a trajectory standpoint. Heavier bullet should translate to more drop. But, from a POI standpoint, you will know once you shoot it.

[canny]

The heavier bullet usually isnt moving as fast which is why it generally hits lower. The harmonics wouldnt factor in as much in most cases(assuming youre shooting out of the same barrel). You never know until you shoot it.

Depending on caliber, at 100 yards I have had 165g and 180g 300 WM bullets have same POI, but at 200 is when you start to see more separation. That is because 100 yards is relatively "close" and with something that shows high velocity the effects of gravity over that span is very small. The harmonics come into play in how the bullet leaves the barrel. It is not uncommon for the heavier bullets to have a higher POI at 100 than a lighter bullet, that would be result of the barrel harmonics.

[Rubberdown]

Some of you math and science whiz’s need to learn the difference between trajectory and point of impact.

Given the 100yard point of impact then the math works but there is no predicting how POI will shift when switching from one bullet to another no matter the weight.

I mean that’s true. Like you say you can’t control things you can’t control. I was just saying what the math says b I had a 308 that shot the same POI With 175s and 168s at 100. My other one wouldn’t do it. Who knows why. I’m sure someone does but not me. I just run the guns and use my app.

[muzzlebrake]

These two comments contradict each other and make my head hurt.

As I read the op’s post I take as he is asking whether or not the two different loads (bullet weight)will have the same impact at 100 yards. The answer is not known until the shots are actually taken and compared. They may very well shoot to the same impact but at the same time may not. It’s not about drop or how far the bullet “flies”. At 100 yards the point of impact is affected where the muzzle is pointing when the bullets exits the muzzle, which boils down to barrel harmonics.

Add in the fact that in general a longer heavier bullet also has a higher ballistic coefficient. My man bun 6.5 shoots 140 gr berger hybrid vld's a full inch higher than it does 130 gr Hornaday ELD match even though the velocity is lower. Therefore you would be 100% correct!

[trophy8]

Boy this thread is entertaining.

Started to throw bearing surface and case thickness and burn rates and case capacity and different styles of bullet ogives into the mix but someone will disagree.

[muzzlebrake]

Boy this thread is entertaining.

Started to throw bearing surface and case thickness and burn rates and case capacity and different styles of bullet ogives into the mix but someone will disagree.

Not me
I have proved it to myself on my old Crony. Always get higher velocity with Barnes bullet over Noslers. Same powder, cases, primers and bullet weight. Only real difference is those nice little grooves 100+fps makes a difference.

[meltingfeather]

Affects of bullet grain wt.

Either mass weight and gravity mean something or they do not.. Which is it?
If you are agreeing that its 100% harmonics then your are dead wrong also..

What drops faster, a marble or a bowling ball?

You said for the same muzzle velocity a heavier pill will drop faster. You sure about that?

This thread got derailed quickly.

OP- to get a ballpark answer to your question use a simple ballistics calculator. You’ll have to have some more data than just two grain weights, but if you have two boxes of ammo you should have what you need. If you really need to know you have to go to the range. There is no substitute.

[meltingfeather]

best to shoot them before hand to confirm.
Thanks guys for all the information.

This is best always. No good guide or outfitter that I know of will let you pull the trigger on game without going to the range first. Bow or rifle.