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 10 1896 Sight and bullet deviation tests rept 06/1897 (Read 940 times)
butlersrangers
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1896 Sight and bullet deviation tests rept 06/1897
May 24th, 2018 at 5:42am
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I found these page entries from the 1897 Chief of Ordnance report interesting. They indicate the progress of installing model 1896 sights on caliber .30, model 1896 and model 1892 magazine rifles.

Also shown are Deviation or Drift results from shooting conducted at Sandy Hook, the Water Shops Pond, and at a "camp", on private property, about seven miles from Springfield Armory.

(I thought this private range might be the Range at Bircham Bend, but, that would only be 3-4 miles from S.A.).

It is of note, that with rifle length barrels, bullet drift was to the left and with carbines, bullet drift was to the right.
(The suggestion that a barrel length, in between, might have no drift may have had an influence on a trial, years later, of the 26" BoOF rifle)?
  
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Dick Hosmer
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #1 - May 24th, 2018 at 1:00pm
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That is REALLY strange about the left drift from a RH-twist bore, and is contrary to similar tests conducted with the trapdoor. I'm guessing there were factors such as whip, or some other harmonic of which they were either unaware or did not test. Could the offset mass of the magazine have had any effect, I wonder? SA used RH and LH barrels to test the TD. I own one of the the LH carbines.
  
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butlersrangers
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #2 - May 24th, 2018 at 2:20pm
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Dick, I think your thoughts are logical on the 'reversal' of drift, between rifle barrels and carbine barrels. (It likely has to be the barrel harmonics of the rifles and carbines used in the 1896-97 testing).

The velocity difference between projectiles fired from rifle and carbine barrels was only around 80 fps.

The gyroscopic twist and direction imparted to the projectiles had to be nearly identical.

I am guessing that later testing and trials gave different results?

The model 1901 rifle sight corrects for drift by angling the eye piece to the Left, as it is moved up the leaf. This would indicate correction for rifle bullet drift being to the Right.

The carbine version of the model 1901 sight has no correction for bullet drift.
  
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Dick Hosmer
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #3 - May 24th, 2018 at 4:16pm
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As does the Buffington sight for the TD. There is a missing factor here and I would not be surprised if it were the mag. FWIW, they chose to use carbine leaves as the basis for the BoOF sight (different range grads of course).
  
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #4 - May 24th, 2018 at 4:49pm
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I never did believe the drift to the left idea that someone got from someplace.  The Buffington sight being set up to correct for drift to the right sorta says it wasn't true.  I could see early Krags being off a bit in windage, with no correction available, and I think that was the beginning of the "against the laws of physics" idea.
  
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butlersrangers
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #5 - May 25th, 2018 at 8:02pm
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A bit of a conundrum, if you get my 'Drift'.

I am inclined to agree with "Madsenshooter" and Dick Hosmer, that with U.S. rifles and their right-hand rifling twist, 'drift' must be to the right.

The model 1901 rifle sight was definitely built to correct for drift by moving the eye-piece to the left, as range increases, which would indicate drift is to the right.

By contrast, the short-careered, model 1898 rifle rear-sight, a.k.a. 'The Dickson sight', had its three notches slightly off-set to the Right of the center-line, (which would indicate a correction for bullet drift to the left).

The model 1902 sight, a rendition of the Dickson sight, has its single notch on the centerline, hence no built in correction for bullet drift. 

As Mr. Hosmer might say, "With Krags, we are often presented with an inconvenient truth". But, I am not sure what the Truth is.

The 'range testing' for drift with The United States Magazine Rifle caliber .30, that was performed in 1895, 1896, and 1897, appears to have been under the supervision of Lt. T.C. Dickson. His name is the signature submitting the report.

It does sound to me from the content of the report, that they were having difficulty completing these 'shooting tests' and may have been getting surprising results.

The bullet drift tables submitted in the 1897 report were repeated in 1904 and 1917 government publications (attached pages).

Also, attached are a couple of pages from Dr. Hudson's practical work on rifle shooting from 1902. The Good Doctor understood sight picture, bullet drift, and trusted his 1901 sight!

I suppose it is possible the old drift tables were flawed, caused some embarrassment, were eventually ignored and worked around, but, they sure got reprinted a lot??? That's the government for you!
  
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Dick Hosmer
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #6 - May 25th, 2018 at 8:56pm
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I cannot back it up with any reports, but I still have to think that the asymmetrical receiver mass could well have some harmonic effect upon the horizontal component of the impact point, especially on the LONG rifle barrel. We KNOW the left drift to be "wrong" as it contradicts all other testing - and, the fact that it self-corrects at extreme range only supports that fact.

I do not know how the firing was conducted. Single-loaded? Possibly, but likely not. With box and follower, etc. removed? I sincerely doubt that. Consider the weight of the box, the follower, and two cartridges, and their moment arms from centerline. Yes, the side-plate has mass too, but the receiver is still right-side heavy (and right side stiffer) to some degree, all of the time. The relative effect would be much less in the carbine of course.

It is my understanding that the extra notches on the 1898 sight were mainly to provide a crude lead for moving targets, not for drift correction, even though they are not spaced equally off-center.
  
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butlersrangers
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #7 - May 26th, 2018 at 6:40am
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Dick: It appears you are thinking along the lines of Major Greer (Chief of Ordnance report 1900).
  
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #8 - May 27th, 2018 at 6:06pm
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Perhaps you have already viewed this.  It is from the 1899 report, if it helps prove/disprove anything.

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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #9 - Jun 6th, 2018 at 3:19am
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Still talking about drift in the 1901 report. See the last paragraph, trying different barrel lengths. Did not find anything in the 1902 report. Looks like they were already focused on a "new magazine rifle" and were giving up on the drift issue of the present magazine rifle.

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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #10 - Jun 9th, 2018 at 1:10pm
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Here is another consideration for drift..........the single lug bolt. From the 1901 Ordnance Report (and the early beginning of the model of 1903):

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Dick Hosmer
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #11 - Jun 9th, 2018 at 2:10pm
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It should be pointed out that the mention of "1894" rifles being converted to cadets is a well-known typo - should have read "1884".
  
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #12 - Jun 9th, 2018 at 5:57pm
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Thank you Dick for clarifying the typo in regard to Springfield Cadet Rifles.

In regard to 'Bullet Drift' with Krag 30" rifle barrels:

If I have read things correctly, it appears bullet drift was actually to the right, but, initial bullet movement or deviation was to the left.

Due to vibration or harmonics of the 30" barreled/action, the bullet left the bore angled toward the left.

The bullet moved in a horizontal arc and eventually "drifted" back toward the Center Line and crossed to the right at around 1,100 yards.

To me, the conundrum now is the 'Drift Correction' built into the model 1901 rear-sight. It angles the eye-piece, increasingly to the left, as range increases. This seems Wrong?

The correction is for a bullet always moving to the right from the axis of the bore. But that is not how Krag infantry rifles were actually shooting in testing.

It seems to me, maybe a shallow parabolic curve to the Right, reaching its maximum at 600 yards elevation (on the sight leaf) and then curving to the Left is what was needed. It would move back to center at 1,100 yards and continue shifting the eye-piece to the Left.

This whole anomaly, with the performance of 30" Krag barrels, must have driven the Springfield Armory crew 'nuts' when they were trying to calibrate the 1901 sight and get it in to production.

BTW - The (3 notch) model 1898 rear-sight was designed for use with the 220 grain bullet moving at 2,200 fps. This ammo was showing even greater bullet deviation to the left, than the 2,000 fps round.

The notches on the rifle version of the 1898 sight are all off-set to the right in relationship to the center-mark. The sight was designed to correct for bullet movement to the left. (Notches have no correction on the 1898 carbine sight version).
The outside notches on the 1898 sights were a correction for 20 mph winds at 1,000 yards and not to provide Lead on a moving target.
« Last Edit: Jun 10th, 2018 at 12:16am by butlersrangers »  
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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #13 - Jun 9th, 2018 at 6:15pm
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This is from Appendix 10 of the 1901 report. Probably only added to the confusion.

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Re: 1896 Sight and bullet deviation tests rept 06/1897
Reply #14 - Jun 9th, 2018 at 6:33pm
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The model 1901 carbine rear-sight and ultra rare model 1901 sight used on the experimental 26" Board of Ordnance & Fortification rifles had no provision for bullet drift.
  
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