Marlin Firearms Forum banner

1 - 20 of 77 Posts

·
Premium Member
Joined
·
7,648 Posts
Discussion Starter · #1 ·
.


Shooting in a cross wind at 300 yards. How much do I hold off to compensate for wind drift? The wind was 40 to 50 mph variable. 45-70 with 405 gr. Lasercast at 1325 fps.
 

·
Premium Member
Joined
·
4,983 Posts
Ha! Well, most folks had an issue at the buffalo match last weekend, 30mph crosswinds....I didn't however, my 630gr bullets just whistled (literally) their way down with no deviation. Everyone else with lighter bullets 405's, and under had to wait for the wind to die down before shooting at 200yds.
 

·
Super Moderator
Joined
·
9,322 Posts
It must be Monday in Idaho.......again.

Jeff
 

·
Registered
Joined
·
676 Posts
I shoot a 550 grain bullet at about 1230 fps if this is a full cross wind I would have around 15 minutes turned in on my MVA sight which is about 45 inches.
 

·
Banned
Joined
·
267 Posts
Ha! Well, most folks had an issue at the buffalo match last weekend, 30mph crosswinds....I didn't however, my 630gr bullets just whistled (literally) their way down with no deviation. Everyone else with lighter bullets 405's, and under had to wait for the wind to die down before shooting at 200yds.
I hate to be the turd in the punchbowl but bullet weight has absolutely nothing to do with a bullets ability to "buck" the wind. Velocity and ballistic coefficient are all that matter.
 
  • Like
Reactions: M700

·
Premium Member
Joined
·
4,983 Posts
007 I would say that in "theory" you would be correct, but I would have to say that in "actuality" at the slower speeds these bullets travel, weight most definitely makes a difference. Now, if you want to talk about the high speed lighter bullets travelling over 2000fps then I would defer to you since I have NO idea (since I don't use them) about those types of rounds. I'm not the definitive expert, by far, but I know what i see at the range.
 

·
Banned
Joined
·
267 Posts
007 I would say that in "theory" you would be correct, but I would have to say that in "actuality" at the slower speeds these bullets travel, weight most definitely makes a difference. Now, if you want to talk about the high speed lighter bullets travelling over 2000fps then I would defer to you since I have NO idea (since I don't use them) about those types of rounds. I'm not the definitive expert, by far, but I know what i see at the range.
If you are interested, I will give you the long explanation but if you are not interested in that then I will state again that only the velocity and ballistic coefficient determine a bullets drift in the wind. Weight has no effect whatsoever. This is true for all bullets at all speeds. In general, slow bullets with poor BC's, such as the 45-70, drift more in the wind. In fact, your heavy round moving slowly almost certainly has more drift than the faster 405's. If the rounds have identical BC's, then you absolutely do have more drift.

Any ballistic calculator will tell you this and they do not lie. It is not a round one chooses for any distances past 150-200 yds. This is NOT saying that it cannot or has not been done. Also, I am only addressing external ballistics here....not the terminal ballistics we all love about the 45-70. Shooting the 45-70 at 200 yards is challenging precisely because it is slow and has a terrible BC. Drift and drop are huge. Other attributes make it a perfect tool for a specific job.
 

·
Premium Member
Joined
·
1,689 Posts
Unfortunately, when a person is trying to score well on short range targets like those at 300 yards in a mild cross wind as described in the original post some additional equipment will need to be purchased. In addition to my home-made wind gauge as described here: http://www.marlinowners.com/forum/3...ard-calibers/140518-my-barrel-too-long-2.html

a person will need to invest in a simple plastic protractor, a Hewlett-Packard 12C scientific pocket calculator, and possibly a text book on trigonometry. For a cross-wind that is perpendicular to your line of fire simply use the protractor to measure the angle formed between the fence post and the out-stretched log chain. Using a direct conversion of 1 degree of angle = 1 inch of allowance; a 32 degree angle would call for 32 inches of windage allowance.

For cross-winds that vary from perpendicular it becomes more complicated and is beyond the scope of this post. Also extended ranges will complicate matters as well as periods of excessive lunar pulls, sun spot activity, and gravitational variances.
 

·
Registered
Joined
·
3,061 Posts
Unfortunately, when a person is trying to score well on short range targets like those at 300 yards in a mild cross wind as described in the original post some additional equipment will need to be purchased. In addition to my home-made wind gauge as described here: http://www.marlinowners.com/forum/3...ard-calibers/140518-my-barrel-too-long-2.html

a person will need to invest in a simple plastic protractor, a Hewlett-Packard 12C scientific pocket calculator, and possibly a text book on trigonometry. For a cross-wind that is perpendicular to your line of fire simply use the protractor to measure the angle formed between the fence post and the out-stretched log chain. Using a direct conversion of 1 degree of angle = 1 inch of allowance; a 32 degree angle would call for 32 inches of windage allowance.

For cross-winds that vary from perpendicular it becomes more complicated and is beyond the scope of this post. Also extended ranges will complicate matters as well as periods of excessive lunar pulls, sun spot activity, and gravitational variances.
I just use an iPhone app. Works great.
 

·
Registered
Joined
·
4,169 Posts
Weight makes a difference because more weight generally means more BC....heavy bullets are longer, longer bullets usually have a higher BC.

There are other contributing factors...such as ogive and velocity, but there is no need for a complicated scientific analysis...or debate.
 

·
Banned
Joined
·
267 Posts
Weight makes a difference because more weight generally means more BC....heavy bullets are longer, longer bullets usually have a higher BC.

There are other contributing factors...such as ogive and velocity, but there is no need for a complicated scientific analysis...or debate.
It is not complicated scientifically and there is no room for debate. Weight, by itself, has as much to do with wind performance as the lunar phase....which is to say, not at all. It is velocity and BC. Truly, I am not making this up.

Apologies to the OP for getting off topic.
 

·
Registered
Joined
·
4,169 Posts
Read what I posted again...specifically the part about "other factors"....I'm not the one trying to debate, and I fully understand BC...I was shooting (and hitting) targets at 900 yards just a couple of weeks ago...as I have done for nearly 30 years now.

You cannot have high BC without having a long bullet....you cannot have a long bullet without having a heavier one...

So....weight does effect BC...not by itself, but it is a factor no matter how you slice it.
 

·
Registered
Joined
·
653 Posts
Just take a sip of tea and hold off half the critter!!:tee:
 
  • Like
Reactions: msharley
1 - 20 of 77 Posts
Top