Pellet guns and ballistic drop/wind compensation

[PFCJon]

I'm using a high powered pellet gun to work on marksmanship since my neighbors would probably not appreciate the use of a real rifle- plus ammo is pricey- and I'm curious if anyone knows a bit about ballistics with these guns.

Basically, today I was shooting in the black at 30 yards with a rifle that shoots .177 at about 800 fps. When the wind picked up my shooting was noticably worse. I went from 1 inch grouping to missing the paper altogether. Do any of you guys know how much a wind of about 15 mph will affect a lightweight round? Will it matter at all at such a short range or was I just shooting badly later in the day? I'm thinking about doing some experiments with range using large targets and shooting at 10 yard intervals without adjusting the sights to see how much the round drops.

Would any of you fellow poolees want me to post this info if I can get a reliable idea of how much the round drops with the 2 rifles I'm using? That's a Winchester 800x and a crappy little Daisy Powerline 856- both from Meijers for the price of what would be a couple weeks worth of 30-06 rounds at the rate I'm going.

[greensideout]

DEPJon, Wind plays a BIG part in where the round is going.

The .177 cal. is small and therefore is more greatly effected by wind.

Your idea of a larger target is good as it will show you the results of the wind upon the round that you have shot.

Of course the slower it goes the more effect the wind has.

Go with the larger target and put the sites at six-o-clock, even with a scope.

Take a deep breath, let it out, hold, squeeze the trigger softly.

If you are not surprised when it fires then you may be bucking or pulling the round off target.

Have fun---I still shoot a 1000 fps air rifle and enjoy it very much.

[BHABIT]

DEPjon...

For ballistics on air guns try...
http://www.airgun.co.uk/airgun_ballistics.htm

Don't let anyone tell you that the slower the bullet the more wind affects it!! This is not ALWAYS TRUE... case in point 300 Wisper.

Semper Fi

[yellowwing]

Are proctective eyewear part of airgun safety? .17 at 800 fps is still a hazard, remember mom's "You'll shoot your eye out!" warnings.

[greensideout]

Originally posted by BHABIT
[B}

Don't let anyone tell you that the slower the bullet the more wind affects it!! This is not ALWAYS TRUE... case in point 300 Wisper.

Semper Fi [/B]


What I told him is true. I'm not, "anyone", I'm GSO. You may use my name when making reference to my comments.

You make a case that differs from fact with the 300 Wisper?

Ok, I'll let you try to explain your mystical theory.

And the explanation is---------------?

[yellowwing]

That's confusing to me also. How can a 300 Wisper defy the laws of ballistics?

The longer that a projectile is in the air, the more time the forces of wind have to push on it.

I'm sure there is an official fancy of way of stating that. But that's my point/question.

[greensideout]

Wing,

I think that he may be referring to the improved ballistic coefficient of the 300 Wisper, (sounds like a "new to me" wildcat round), but I will let him explain why things fall upward before we discuss that.

[greensideout]

DEPJon,

I was wondering, did you try anything that I said and did it help?

[PFCJon]

I haven't had a chance to go out yet in the last couple days, but I will definitely post after I get back out and try some of your suggestions. Thanks guys
Jon

[PFCJon]

So I did what you suggested and had some big improvements over the weekend...

Step one: lose the scope, noone mentioned it, but the M16 at boot camp won't have one sooo....

Step two: readjust the sights to zero in on the 6 oclock position

Step three: work on breathing as suggested

The results: my grouping for shooting in the standing/offhand position is as good as it was shooting prone with a scope last week. Thanks guys!!

I'm also thinking about a heavier pellet for windier days. I'll have to adjust for more ballistic drop, but it wouldn't be as affected by a crosswind if I understand the physics of it all correctly.

[BHABIT]

OK GSO...
The 300 Whisper® is a new concept in the development of small case capacity, highly efficient cartridges combined with bullets of extreme ballistic efficiency.

The 300 Whisper® was designed for the purpose of firing extremely heavy, accurate, ballistically efficient bullets at sub-sonic velocities and is now the state of the art long range cartridge in suppressed weapons. It delivers more energy more accurately than any existing sub-sonic round at 200 yards {and a lot further} (except other Whispers®). In addition, it has interesting sonic capabilities - possessing greater versatility than any other cartridge capable of performing in these vastly differing arenas.

The above came from the following link...
http://www.quarterbore.com/300whisper/

Or you might try this one...
http://www.accuratereloading.com/300whisper.html

Or maybe this one...
http://www.lasc.us/RangingShotLongWhisper.htm

GSO.... I realize that your MOS probably didn't cover the finer arts of suppresed weapon balistics... but mine did. been using this cartridge for years as well as many others.

I admitt that I know little about pellet guns... they were never very popular in my MOS... we tended to us the real thing and trained as we fought.

[yellowwing]

Pulled from http://www.lasc.us/RangingShotLongWhisper.htm
When the 7 TCU’s 140 grain bullet hits the ram, it’ll be going 1349 fps. In other words, it’ll have lost a whopping 551 fps, or nearly 29% of its original velocity. In a very gentle 5 mile an hour side wind, it will have also drifted over nearly 6 inches.

The 300 Whisper will be a very different story. When its 220 gr bullet hits the ram, it’ll still be going 983 fps. Amazingly, it will have only lost a miserly 67 fps over the 200 meter course! Compare that to the 7 TCU loosing 551 fps at the same distance. Well, you might say, there’s bound to be a lot more wind drift because the bullet is moving so slow. Wrong. That’s not how it works. Wind drift will be only 3.8 inches or 36% less than the 7mm bullet.


My apologies Gunny!

This "know it all Cpl" learns something new every day here!

Semper Fi!

[greensideout]

Originally posted by BHABIT
OK GSO...




The above came from the following link...
http://www.quarterbore.com/300whisper/

Or you might try this one...
http://www.accuratereloading.com/300whisper.html

Or maybe this one...
http://www.lasc.us/RangingShotLongWhisper.htm

GSO.... I realize that your MOS probably didn't cover the finer arts of suppresed weapon balistics... but mine did. been using this cartridge for years as well as many others.

I admitt that I know little about pellet guns... they were never very popular in my MOS... we tended to us the real thing and trained as we fought.


Ok BHABIT , here we go---lol.

We were talking apples when you jumped in with an orange.

The only changes we could make with the .177 cal pellet rifle to help with wind was to change the speed of the pellet or it's weight. Both of those will help just as I said they would.

In one of my posts I suggested that you may be talking about the ballistic coefficiency of the 300 wisper. Bingo! You were.

The sub-sonic and heavier bullet concepts are so basic to marksmanship and so elementry to shooting that I'll pass on regurgitating them because you seem to understand them and it would serve no purpose in this discussion.


WING;
You were not wrong and proved it with the 7 mm TCU vs 300 Wisper as it applies to ballistic coefficiency.
Shooting both 200 yds, (the same distance), the wind will drift the 140 gr more easily then the 220 gr, even though it is moving slower. Think ping-pong ball vs bowling ball.


DEPJon;
Good to hear that it helped. Keep shoot'in!


BHABIT;
About that MOS comment you made---I was just trying to deside what my favorite helo door weapon was. I think it was the Daisy Red Rider.

[yellowwing]

Don't let anyone tell you that the slower the bullet the more wind affects it!! This is not ALWAYS TRUE...
No the Whisper is not a magic physics defying round. The last link researched explained that to go from 170 to 220 grains, they extended the length of the Whisper 300. Thus giving it a much improved drag coefficient.

I think the Gunny proved his basic point.

The other links show average 5 shot groupings. Less than 1 inch at 100 yards!

[BHABIT]

The intent of my original post was this...

1. Ballistical statements NEED to be qualified...

2. ALL ballistical projectiles can be modified in one fashion or another to cheat the so called RULES.

3. I was trying to peek Depjon's interest enough to hopefully get him to think outside the box.

Other that I did what I set out to do... I gave him a link that dealt with pellet ballistics and probabley gave him some food for thought as he calculates his down range tables.

As far as talking about ORANGES?? don't think so.... I wasn't the one who gave him erroneous information.

I just wanted to be helpful and accurate in what I was telling him.

[greensideout]

We all wanted to be helpful and he said he has already improved.

So there ya go!