Jump to content


Remembered Today:

Photo

Bullet drop at 200 yds


12 replies to this topic

#1 museumtom

museumtom

    Lieut-General

  • Old Sweats
  • 5,104 posts
  • Gender:Male
  • Interests:The Great War

Posted 08 December 2010 - 07:28 AM

I am working my way through a 1914 article, thats the only way to descirbe it. It says that a bullet travels at 2,000 feet per second and drops 6 inches the first 100 yads and 2 feet at 200 ys. I get the impression that this was writte about black powder rifles and not the SMLE, Any ideas? Should this article be about pre ww1 rifles?
Kidn regards.
Tom.

#2 Doc2

Doc2

    Lieut-Colonel

  • Old Sweats
  • 1,039 posts

Posted 08 December 2010 - 07:51 AM

I am no expert, but that certainly would not apply to modern loadings of the .303 round. Most of those have MV of about 2400-2600 fps and a 200 yard drop of about 12 inches. On the other hand, a blackpowder muzzle loader giving 2000 fps is fast (though possible with some loadings) with a drop at 200 yards of 21-26 inches, depending on bullet weight etc. I do not know about the ballistics for rifles in between, but I suspect your guess that the article is talking about pre-SMLE rifles. Doc

#3 TonyE

TonyE

    Major-General

  • R.I.P.
  • 3,648 posts
  • Gender:Male
  • Location:London SW19
  • Interests:British military Small Arms and ammunition.

Posted 08 December 2010 - 09:48 AM

Those figures are wrong for any small bore rifle (i.e. not a large calibre black powder cartridge like the .577/.450 martini Henry or similar) firing a pointed spitzer bullet at that sort of velocity.

For the SMLE in WWI the normal service round was the Mark VII ball with a 174 grain bullet at a muzzle velocity of 2,440 fps. This was introduced in 1911, but for earlier marks of SMLE made between 1902 and 1911 and not re-sighted, and for the long rifles of the Territorials and colonial units the cartridge was the ball Mark VI. This had a 215 grain round nosed bullet with a muzzle velocity of 1,970 fps.

I do not have British tables for bullet drop as generally the tables give rifle elevation in minutes of angle rather than bullet drop. However, an approximation can be made using modern reloading tables (mine are by Hornaday). These suggest that if the rifle is zeroed at 100 yards, a bullet with a ballistic coefficient of .36 fired at 2400 fps will drop about 6 inches at 200 yards. The Mark VII, being slightly heavier might do a little better as it will retain velocity more.

The nearest to the Mark VI bullet in the tables is a 200 grain round nose fired at 2,000 fps with a BC of .30, Again, if zeroed at 100 yards the bullet will drop about ten inches at 200 yards.

However, that is what sights are for. If the sights are set at 200 yards then the bullets will land at the aiming point at 200 yards!

As a rule of thumb, if the sights are left at the low setting of 200 yards, in theory you will not be more that an inch or so out at any range in between, which is this more than accurate enough for most purposes. However, remember that the specification of both rifle and ammunition are outside of this. Accuracy acceptance for Mark VII ammunition was just under three minutes of angle (actually a Figure of Merit of less than 8 inches at 600 yards) so at 200 yards the average group will be 5-6 inches. Add any inaccuracies in the rifle and the firer and you can see that the errors soon add up.

However, to return to your original question, the numbers quoted are exaggerated.

Regards
TonyE

#4 museumtom

museumtom

    Lieut-General

  • Old Sweats
  • 5,104 posts
  • Gender:Male
  • Interests:The Great War

Posted 08 December 2010 - 10:26 AM

Thank you Tony and Doc.
I attach the article for your reference.
Kind regards.
Tom.
About a Rifle.
We need rifles—good ones. We need to be able to handle them and to shoot straight. When taking position to fire keep the body rigid but not stiff. The firer should be at right angles to the target, legs slightly apart, with his elbows and lower part of chest forming a triangle. Rest the stock of the rifle in the hollow of left hand, the thumb slightly resting on the side of or just under the barrel, holding the gun firmly but not tightly. It is the right hand does all the work, and keeps the sights straight and true on the “bull.” The ball of the thumb should be pressed against the thick part of the stock, the fingers should grasp, or partly grasp, the “hand,” and the first joint of the first finger should rest lightly on the trigger, whilst the heel; of the stock is held, by steady pressure of the right hand right into the shoulder. You thus avoid the kick. Having thrust your cartridge into the .rifle and closed the breech with a smart snap, the rifleman must first get the stock comfortably fixed against his shoulder, then—though the mode of procedure here varies—bring your foresight down from the top of the target to about an inch below the “bull,” then, fixing your attention on the little black disc, get your foresight; seen through the V in the backsight, just touching the “bull,” pull—not jerk—the trigger, and your first bullet has been sent, at some 2,000 feet per second, towards its mark. A bullet does not travel in a straight line, but, under the influence of gravity and friction, begins to drop almost as soon as it leaves the muzzle. The bullet of a service rifle drops six inches in the first 100 yards, but when it had gone 200 yards it will have dropped not twelve inches but two feet. The drop increases with the distance. Were there no sights, on the rifle and you wanted to hit a mark at 200 yards you would have to aim two feet above it. The sights of a rifle enable you to keep your eye on the mark although the muzzle of the rifle is actually pointing above it. The movable slide of the backsight enables you automatically to point the muzzle just so many feet above the mark aimed at as is necessary to counteract the known drop of the bullet at various ranges.
Judging Distances.
Soldiers, volunteers, everybody, need to be able to judge distances. In war a man’s life may hang on his ability to estimate the range of a foeman. It’s an interesting business to be able to judge distances. To learn measure out a distance of, say, one hundred yards, and carefully study it. Then pick out objects in other directions which in your estimation are one hundred yards away, and test your judgment by actual pacing. In this way you will come automatically to recognise a distance of one hundred yards or thereabouts, and you can then estimate a longer distance by reckoning it as being so many times one hundred yards. Another exercise is to get a friend to show himself standing, kneeling, and lying down at various known distances. You should then carefully note and memorise the different appearance he presents according to the distance. You will find that at one hundred yards you can clearly see details of his clothing, which are only partially visible at 150 yards, and quite invisible at 200 yards. Distances are over estimated when the observer is kneeling, sitting, or lying; when both the back-ground and the object are of a similar colour; when heat is rising from the ground; when the ground is undulating or broken, or when looking over a valley; when the object lies in the shade, is only partially seen, or is viewed in mist or a bad light. In long streets, avenues, and ravines, things look farther away than they really are. Distances are underestimated when the sun is behind the observer; when both the background and the object are of different colours, and again when the object is large or is seen in a bright light or clear atmosphere. Should the intervening ground be level, or covered with snow, the object will appear nearer than it is. The observer should also add five to ten per cent, on to his original estimate when he is looking over water or a deep chasm, or, again, when looking upwards or downwards.

#5 Doc2

Doc2

    Lieut-Colonel

  • Old Sweats
  • 1,039 posts

Posted 08 December 2010 - 11:21 AM

Obviously I am not able to clearly define the rifle discussed from that short article, but one line jumps out at me. "Having thrust your cartridge into the .rifle and closed the breech with a smart snap...." That is obviously describing single-loading, not the use of a magazine. I guess it could refer to single loading a magazine rifle with a magazine cutoff, but it really sounds more like a description of a Martini-Henry to me, for some reason. Given the various loads available for the Martini-Henry, I can't discuss the MV or bullet drop issues. In reality, the Mark VI .303 round could be the one discussed, as the ballistics would be a drop of about 20-24 inches IF THE RIFLE WERE HELD PARALLEL TO THE GROUND, rather than sighted in at 100 yards as discussed by Tony. Given that your article was published in 1914, if I had to put money on it, I would have to bet that it is discussing one of the predecessors of the SMLE or one of the pre-1911 SMLEs in caliber .303 Mk V or Mk VI. Doc

#6 TonyE

TonyE

    Major-General

  • R.I.P.
  • 3,648 posts
  • Gender:Male
  • Location:London SW19
  • Interests:British military Small Arms and ammunition.

Posted 08 December 2010 - 11:34 AM

I agree that the velocity given indicates a Mark VI round (although the earlier Marks II to V had a similar MV) and the description of "a sharp snap" does sound like a .303 inch Martini Enfield. There were numbers of these dragged back into service in 1914 so it is entirely possible.

The MV of the .45 inch Martini-Henry was 1,340 fps.

Regards
TonyE

#7 Retlaw

Retlaw

    Major

  • Old Sweats
  • 424 posts
  • Gender:Male
  • Location:Accrington Lancashire England
  • Interests:Continuing the reaseach of the Accrington Pals for the late William Turner. Also researching all the men who took the Kings shilling 1914- 1918 in Greater Accrington.

Posted 08 December 2010 - 04:27 PM

Could'nt find my old score book for the .303, but I've scanned the range tables for the 7,62.
they are graduated in minutes of angle, zero at 200 yrds the bullet drop at 300 is 2.5 inches
at 400 yrds the drop is now 11 inches, at 500 yrds the bullet has dropped to 45 inches,
by the time its got to 1000 yrds it has dropped 30 feet.

Retlaw.

Attached Files



#8 museumtom

museumtom

    Lieut-General

  • Old Sweats
  • 5,104 posts
  • Gender:Male
  • Interests:The Great War

Posted 08 December 2010 - 06:08 PM

Thank you one and all. This is all very interesting.
Kind regards.
Tom.

#9 Phil_B

Phil_B

    Lieut-General

  • Old Sweats
  • 10,076 posts
  • Gender:Male
  • Location:Lancashire, England

Posted 08 December 2010 - 06:32 PM

By my simple way of thinking, it matters little what the forward velocity is, the bullet is falling vertically under gravity. Calculation shows that a body falling vertically for 0.3 seconds (the time for a bullet to travel 200yds at 2000fps) would travel 17 inches. :unsure:

#10 Retlaw

Retlaw

    Major

  • Old Sweats
  • 424 posts
  • Gender:Male
  • Location:Accrington Lancashire England
  • Interests:Continuing the reaseach of the Accrington Pals for the late William Turner. Also researching all the men who took the Kings shilling 1914- 1918 in Greater Accrington.

Posted 08 December 2010 - 07:11 PM

By my simple way of thinking, it matters little what the forward velocity is, the bullet is falling vertically under gravity. Calculation shows that a body falling vertically for 0.3 seconds (the time for a bullet to travel 200yds at 2000fps) would travel 17 inches. :unsure:



During my target shooting days I did a lot of my own relaoding, and chronographing of ammo.
If a bullet leaves the muzzle at 2500 ft p sec, at 500 yrds its down to 1800 ft p sec, at 1000 yrds
it will be just over the speed of sound, but wiil have taken 2.4 seconds to get there.
There are ballistic programs available to help with velocity, bullet co-efficient, trajectory, and
wind deflection.
A WW1 Vickers firing at a target 1000 yrds away can have 20 bullets in flight before the first one strikes.

Retlaw


#11 TonyE

TonyE

    Major-General

  • R.I.P.
  • 3,648 posts
  • Gender:Male
  • Location:London SW19
  • Interests:British military Small Arms and ammunition.

Posted 08 December 2010 - 07:47 PM

By my simple way of thinking, it matters little what the forward velocity is, the bullet is falling vertically under gravity. Calculation shows that a body falling vertically for 0.3 seconds (the time for a bullet to travel 200yds at 2000fps) would travel 17 inches. :unsure:


Whilst essentially you are correct Phil, the muzzle velocity does matter. If the bullet travels at twice the speed it will arrive at 200 yards in half the time and thus only drop half the distance. I know that is simplistic and ignores ballistic coefficient and form factor etc., but it is good enough for the purposes of this discussion.

Regards
TonyE

#12 Phil_B

Phil_B

    Lieut-General

  • Old Sweats
  • 10,076 posts
  • Gender:Male
  • Location:Lancashire, England

Posted 09 December 2010 - 10:28 AM

Quite right, Tony. That`s why I said it would drop 17" in the 0.3 secs of travel. The time (and drop) would of course vary with velocity. I feel that the aerodynamics, weight etc of the bullet should have an influence but I can`t see how, other than affecting velocity as above.

#13 MikB

MikB

    Brigadier-General

  • Old Sweats
  • 1,897 posts
  • Gender:Male
  • Location:Redditch
  • Interests:Military/Naval history, Engineering history, old telescopes, ballistics.

Posted 09 December 2010 - 11:03 AM

I think PhilB's pretty much right. Some British ammunition manufacturers were still publishing Drop In Inches - assuming a dead-horizontal firing - in the 1960s, though trajectory against an established zero was a very much more useful statistic.

Even so, the alleged 2 foot drop doesn't make sense even if you imagine the writer might've forgotten to average the downward drop velocity.

Regards,
MikB