1903 Springfield Question

[Highgravity]

Does the built in spin drift adjustment on your rifle track properly for you with cast boolits?
My new to me rifle acts as if there is no drift when I raise the elevation. My POI walks to the left.
My load is 16gr. 2400 and lee 180gr. runs at 1500 fps. I am new to this type of site and am trying to
get my head around what is going on.

[gnoahhh]

Hmmm. Never noticed that before, but on the other hand I never do any cast bullet shooting with mine past 200 yards. Perhaps the 1905 sight drift only works to compensate for high speed jacketed spitzer bullets? I'll be curious too to see if anyone has input.

[Highgravity]

After having slept on it, I thought time of flight had more to do with the spin drift (less velocity= more drift per given distance) thus self correcting.
Not so, I guess. I've now settled on the idea that the exaggerated elevation corrections to compensate for the lower velocity are overdoing the drift.
What do you think?

[W.R.Buchanan]

I don't think compensation for Spin Drift was built into a Springfield Sight. I may be wrong but it seems a little too much information for a Conscripted Doughboy to deal with. I don't even know if they knew about Spin Drift in 1906.

First: you are dealing with an iron sight, and anything past 600 yards is going to require divine guidance rather than correction for spin drift.

Also the sight radius on a Springfield is about 20" That means a 1 MOA correction will be about .004-.005". The ladder on the sight could wobble that much and nobody I know of could adjust for that little movement anyway. Spin Drift is one of the factors that come into play way down the line from what 99.999% of shooters are ever going to experience. Coriolis Force has about the same effect, and both only affect bullet travel at very long ranges.

Also normal windage corrections IE: speed of the crosswind, would have way more effect past 200 yards than spin drift ever will.

Wind is more likely to influence your boolits than any other factor. The other factors are splitting hairs unless you are shooting F Class or Sniping at 1200 yards.

Randy

[M-Tecs]

The Trapdoor Springfield Buffington 1884 sight is angled to compensate for spin drift. The 03 sight is a version of the Buffington 1884. The 1903 sight is angled like the 1884 just less. Top two pics are 1884's and the bottom is an 1903. My 1884 sights track spin drift very well but I have not shot my 1903 enough at distance to comment.

[M-Tecs]

More detail on the spin drift of the 1884 sight https://books.google.com/books?id=BdVCAAAAYAAJ&pg=PA86&lpg=PA86&dq=buffington+sight+instructions&source=bl&ots=r_j0xlUje5&sig=S_k3M0dSgWVDv2PKP3MQwrssaok&hl=en&sa=X&ei=vl4xVeLYEc_-sAT794HwBg&ved=0CCoQ6AEwBDgU#v=onepage&q=buffington%20sight%20instructions&f=false

[Highgravity]

Thank You for the link. I swear the more you learn the more you realize you don't know. LOL

[Larry Gibson]

Yes spin drift is built into the M1903 sight as shown. However, the built in correction is for a 150 gr bullet at 2700 fps.

A 311291 at 1900 fps has the following spin drift with a 10" twist;


100 yards; .13"

200 yards; .58"

300 Yards; 1.17"

400 yards; 2.93"

500 yards; 5.05"

All will be +/- with the correction for wind drift at those ranges.

Larry Gibson

[Multigunner]

Interesting facts I ran across years ago.
When the bullet leaves the muzzle of a 1903 theres a tiny jump to the left. Possibly due to the very slight horizontal vibration of the receiver due to the opening of the ejection port. The center of the bullet traveled a few hundredths to the left of the bore line till spin drift canceled that out at between 500 and 600 yards, the original battle sight was zeroed at the range where spin drift canceled bullet jump. In this way the 1903 could be bore sighted with the battle sight and would be very nearly dead center in the vertical plane out to 600 yards, holding under the target as needed, with spin drift then curving the bullet path to the right increasingly at further ranges.

As the bullet loses velocity the rate of spin stays very nearly the same so drift increases at longer ranges.

At some point the USMC altered the battle sight for a more dead on hold at closer ranges. Not sure if they actually altered the rear sight or just installed a taller front sight blade which would have been the easiest way to go about it.

[W.R.Buchanan]

This is amazing to me. Can anyone actually realize the effects of this in the real world? Or were the sights designed to take it out of the equation.

I mean, 5" at 500 yards seems to be cutting it a little close for a ladder sight, as does 1/8" at 100,,, mainly cuz you can't see that close to line up the sights with the target at those distances without magnification.

It all seems mute to me. But I guess that doesn't mean they thought it was.

Did the German Sights have this feature included in their design as well?

The things I learn here never cease to amaze me!

Randy

[M-Tecs]

The effects of spin drift increase as distance increases. With the 45/70 it's something like 30" at a 1,000 yards and 170" at 2,000 yards. The sight were designed to be used for fire for effect at long ranges.

[W.R.Buchanan]

Mtecs: I read most of that link and it appears to me they are talking about "Wind Drift" not "Spin Drift?"

Did I miss something?

Randy

[M-Tecs]

Randy

You are correct that they mostly instruct on the wind drift but in para. 220 on pages 86 & 87 it talks a little on the Buffington sight and the built in drift.

[W.R.Buchanan]

People who think this shooting thing is all done at Sight Alignment and Trigger Control, are really missing alot of the finer points.

I learn something new here everyday.

I guess that's why I keep coming back.

Randy

[too many things]

another factor would also come into play. A 2groove and 4 groove would be different. I wont worry about it as 400yds is too far to change targets

[Multigunner]

Well the mechanism of Spin drift is the high speed rotation of the bullet causes a low pressure bubble to form near the base of the bullet drawing the base in the direction of the bubble which turns the nose to one side.
This is a sort of Bernoulli Effect, much like the effect of an aircraft wing, helicopter rotor blade, or propellor..
The surface features of the bullet, how many grooves etc, might make a difference in where the bubble forms and how much the pressure difference would be.

[Light attack]

I do believe that the Marines installed a taller front sight on the 1903/

Wish I had a micrometer for the ladder sight.

[Scharfschuetze]

An interesting aside is that the 1903A3 rifle of WWII had a rear aperture sight that, as far as I know, did not compensate for spin drift. As alluded to earlier, I don't think that foreign rifles of the era made any compensation for spin drift nor have US rifles post 1903 Springfield. That would include the 1917, 1903A3, the M1, the M14 and the M16/M4 series of rifles.

I have always been a bit conflicted over the spin drift question, although I understand the physics behind it to some extent. At ranges up to 600 yards, I do not adjust my zero for it, but at longer ranges (with a right hand twist) I just use a standard 1 MOA left deflection on my sight (scope or iron) to compensate for it on 7.62 NATO and 30/06 rifles. I really worry more about deflection caused by wind than the spin drift. The Lee Enfield with its left hand twist rifling will actually require correction to the right for compensation.

By the time you stop to figure out spin drift, coriolis effect, the ballistic trajectory of your load and its ballistic consistency as well as the atmospheric issues of temperature, wind direction, wind speed, target displacement due to mirage (light refraction) and what you had for breakfast, hitting at long range can get to be quite fun. It is truly is amazing what a good rifle and cartridge can do out at ranges nearly a mile away.


Wish I had a micrometer for the ladder sight.

I have both an original PJ O'Hare micrometer and a replica version of it. I think that you should be able to find one with a quick Google. Here is what they look like on a 1903.

[M-Tecs]

Wish I had a micrometer for the ladder sight.



This is where I purchased mine http://www.buffaloarms.com/Detail.aspx?PROD=1086893

[Multigunner]

The Lee Enfield with its left hand twist will actually require correction to the right.

The front sight base of the Lee Enfield is off set to the left (which induces a correction to the right) to compensate for both bullet throw due to flexing of the action body and spin drift from the left hand twist.