Artillery Rear Sight Offset???
 

I'm reading an ad at Phoenix Investment Arms, about the artillery Lugers, and it says -

"Sometimes in examination people think the leaf site is bent. However, when raising the site to the full 800 meter position reveals a 7�° left movement. This design compensates for the rifling on the 200 mm barrel which gives the bullet a twist in flight and if properly adjusted will permit a corrected point of impact. Another example of Luger engineering."

Here's the URL -

1918 DWM Artillery

I've only physically looked at one artillery Luger, and didn't really notice anything odd about the rear sight...

Is this true???

I'm not clear on how the 7�º "movement" is accomplished...Is the tangent sight axle offset??? Is the sight base itself cut at an angle???

On a related topic, I've read several threads here about Phoenix Investment Arms...Can their little historical tidbits be believed??? They do seem to have a lot of them...I was particularly interested in the dimensions they gave for the barrels on the "fat barrel" Lugers...

I believe that it is correct that the leaf raises to one side as it goes way up to compensate for bullet drift caused by the rotation. Sort of like the 800 Meter sight for a 9mm, maybe just a bit overly optimistic/engineered. But it does show that they were mindful of the effects of rotational drift.
DJU

massed fire!
 

Back then, maybe even now?? They studied the effects of massed fire... everyone shooting as much as they can, as fast as they can, down range in hopes of less people to fight in close!! (worked with arrows too?) It has been borne out in WW1, WW2, and Korea... don't know about the rest... I find 800 meters pretty optimistic, as I've never had much luck with the 9mm at over 25 yards?? (exception, one unlucky duck on a stock dam at 100yds on a windy day??) :evilgrin: But, the fact remains, ballistically, they would perform, and probably were tested at some point in time to make the designers think this way... combat guys could enlighten us more on this then historians... Best to all, til...lat'r...GT

Here's a previous discussion.
http://forum.lugerforum.com/showthread.php?t=20239

Hmmmm...Some quite interesting comments/threads there & here... :)

I was more interested in the actual physical makeup of the tangent sight itself...is the axle hole drilled at a 7�º angle to the barrel??? Or is the axle itself machined off center, to impart a cant while raising??? I can't tell just from looking at those pics...

I couldn't see any real anomaly in the sight while inspecting an LP-08 last week...but I wasn't looking for one either...

The Earth's rotation in relation to firing a Luger...Yes, I can understand how scientists in Germany might make a definitive study of this... :rolleyes:

postino -

The position of the hole drilled through the forward end of the rear sight is done in such a way that as the rear sight is raised, it gradually moves very slightly to the left. This movement to the left is most noticeable when the sight is at or near its full 800 meter setting.

There has always been the notion that it is to the advantage of your troops to be able to put as much lead as possible as far down the range as possible while the enemy troops are still at considerable distances. In those times the goal was to try to put lots of bullets in the vicinity of the enemy and it was termed "barrage firing."

Although I have not tried using the LP08 at such long ranges yet, I doubt it will be very accurate at these longer distances.

However, I think I remember reading somewhere that some German military manual or publication of the time did state that the LP08 would put a bullet through a French helmut at a distance of 800 meters. So if that is true, you still would not want to be hit by one of these bullets at that distance.

Mauser720
Ron

I wonder how long, and how many rounds, it took them to establish that it would, in fact, penetrate a French helmet at 800M?
Sounds like a fun afternoon at the range. And how do I get a job like that?
DJU

Not as fun as a tester, but in the early 1911 tests (deciding that a 45 ACP was needed), Col Thompson and other military members tested assorted cartridge bullets and weights on live cattle and human corpses.


Ed

Perhaps if there is an artillery owner who has the time and good camera, a series of photos can be taken from the rear of the pistol with the rear sight leaf set to different elevations to give postino some idea of the operation of the sight...

Unfortunately, I just don't have the time right now... or I would do it myself.

..Or how many Frenchmen... :D

I just got my artillery and thought maybe I had a bad sight until finding this discussion.

I'll give the sequence shots a go.
Rear view looking forward
http://forum.lugerforum.com/picture....&pictureid=420
http://forum.lugerforum.com/picture....&pictureid=416
http://forum.lugerforum.com/picture....&pictureid=417
http://forum.lugerforum.com/picture....&pictureid=418

Top view

http://forum.lugerforum.com/picture....&pictureid=419
http://forum.lugerforum.com/picture....&pictureid=421
http://forum.lugerforum.com/picture....&pictureid=422
http://forum.lugerforum.com/picture....&pictureid=423

heyjerr -

Thanks for the pics! :thumbup:

Unfortunately, I'm still confused... :(

You and me both!:confused: until I looked closer and figured out what's up.
On mine, the entire sight mount is not perfectly level to start with when viewed from the front. Then it's magnified even more by not having the pinholes on the mount line up. When looking from the front, the pinhole on the left side of the mount is higher than the right side.

Front view showing mount base is not level. Red lines added to show location of pinholes.
http://forum.lugerforum.com/picture....&pictureid=426

View from right side. Notice the distance between the pin and top of the sight.
http://forum.lugerforum.com/picture....&pictureid=424


View from left side. Notice the distance between the pin and top of the sight.
http://forum.lugerforum.com/picture....&pictureid=425

heyjerr,

Please re-post your photos HERE on the lugerforum. There is a sticky at the top of the New Collectors forum that explains all the reasons, but the ones you posted at smugmug.com are not visible to many visitors... including ME. Those types of sites are blocked by many employer's network security firewall.

I think we'll have to get a comment on a "pristine" LP-08 owner on this...


OK, I believe that's what does the "7�º tilt" that Phoenix alluded to...The offset pin holes allow the sight to raise off-center...You might find, if you measure from the front edge of the sight base, that the pin centerline-to-front edge measurements are different, too...

That's just a WAG, but it makes sense... :)

With the New Collectors Forum not near the top, I missed this guidance until now. I've uploaded the photos and the links so it should work properly now. Thank you.

I agree that it would certainly help to have a pristine owner comment on this as well. My entire sight is a different blue than the rest of the gun so I can't even be sure it's proper.

BTW, I took the sight apart and the portion that elevates also has a difference between holes on the left and right sides.

Heyjerr -

Regarding this portion of one of your posts: "On mine, the entire sight mount is not perfectly level to start with when viewed from the front."

I have a pretty decent 1915 LP08 and I can not see that the rear sight mount is not perfectly level to start with. It looks level to me. (?)

The bluing on my rear sight and rear sight base matches the rest of the gun, except for the top side of the little piece that slides up and down the 100 to 800 meter scale. The blueing on this top side of this particular piece is a slightly "bluer blue" (for want of a better description). However, since this little part is serially number to the rest of the gun and the font is perfectly matched to all the other small serially numbered parts, it was definitely this way when it left DWM.

One thing I do notice in your photograph of the two-digit serial number on the right side of this little sliding piece is the quality of the stamping. Is that a "19"? It looks like the "1" and the "9" do not line up very evenly. And the "1" (if that is what it is) seems more deeply struck than the "9".

On my example, this two-digit is very neat, perfectly lined up and perfectly struck. ("86" in the case of my example)

Could it be that on your example this part has been re-stamped to match the rest of the gun? Or another possiblity might be that at this late point in the war, the quality of the stampings was deteriorating due to the logistical exigencies of the war. I do not know.

At least on my example, when the rear sight is in its fully down position, everything seems to be perfectly level.

The photographs that you took to show the difference between the height of the pin on the left side as compared to the height of the pin on the right side are very good. Mine look exactly the same way.

The main difference between my 1915 example and your 1917 example should be that the 1915 has the fine tuning adjustment screws on both the rear and the front sight.

Hope this helps.

Mauser720 - Ron

I used to collect artilleries back in the 70's-80's and shot them quite a bit, sometimes at pretty extreme ranges. Living in New Mexico where the wide open lives our shooting range was on the edge of a river valley and we had our targets set up at 400 and 900 yds. The 400yd target was hard to see so we normally shot at the 900yd target. Shooting an artillery at 900yds is an eye opening experience. You wouldn't believe how long it takes for that pokey 9mm bullet to get out there or how accurately you can shoot at that range. I will testify to the accuracy of the sights and while a man sized target is an iffy hit at 900yds it is possible to get them pretty close. At 400yds it was actually possible to nail the steel gong with about 50% of the mag consistantly. All this of course was done using the stock. In my opinion the guns are pretty useable without the stock at closer ranges. They may seem ungainly compared to the 4" barreled lugers but compared to other pistols they are actually not too bad. For long range shooting though the stock is pretty much a must.....

Just my opinions of course based on actual shooting. I never noticed the sights offsetting but if they did than obviously it works.

Frank

Frank,

I agree completely. We do a lot of long range pistol shooting with various hand guns, and a C96, LP.08 or 6" Navy ( I've used all three) with stock attached would get someone's attention pretty quickly at 500+ yds. I wouldn't want to be standing out there if somebody was determined and skilled enough to ruin my day.

Ron

Being a long range, high power shooter, let's talk ballistics for a minute. Can a 9mm go 800 meters? Sure. Can it do so accurately? Prolly not. I regularly shoot .308 and 30.06 at 600 yds, and a 6.5 X 284 at 1000yds. Planning reloads, you have to keep the bullet supersonic til it hits. Generally 1100fps. Muzzle velocity on the .308/ 30.06 is in the 2500-2700fps range to do this, with a 175-190 gr. bullet. The 142 gr. bullet leaves the 6.5/284 at 3200+. A 9mm 115-125 gr. muzzle velocity is 11-1250?

A bullet that slows to subsonic will start to tumble, and weave around. It is still dangerous, and will do harm. But I think the French Helmet thing was propaganda. Probably worked as the treaty made them stop making artilleries.

FN

for most rifle bullets there is a definite correlation between the transition from supersonic to subsonic and the tumbling of bullets. It all has to do with stability and long thin bullets which fly well at long distance are not terribly stable when the spin slows and the buffeting of the transonic shockwave starts. That is the biggest cause of the inaccuracy at long range. I've seen the same issues with my long range stuff like the .50 cal and the 20mm. However, for pistol bullets the same doesn't hold quite so true. There is some instabilty at the point where the bullet goes transonic and the shockwave moves back in front of the bullet but it is nowhere near as extreme or destabilizing to the short bullets fired from handguns. I'm not trying to say that the 9mm parabellum is very accurate at 900 yds but its not quite so bad as you seem to think. When we dug bullets out of the sand dune at 900 yds the 9mm bullets had always hit point first and showed some impact damage like having the plating scratched off by the sand at impact. The same was not true of the .223 stuff we fired at the same range. We normally found the bullets lying pointy end toward the shooter and they were so nice and undamaged that they could almost have been reloaded, except for the rifling grooves of course. The 9mm bullets also kicked up a pretty good cloud of sand at that range while the .223's were nearly undetectable. The whole point I'm trying to make here is that the 9mm is not a good round for long range shooting if your intent is to hit a particular target but for "volley fire" type shooting it can be pretty effective and dangerous to the attacker. Accuracy is good enough to get them in the ballpark too....

Frank

The total range of a 9mm is within the 1200 - 1500 meters, for all I know this is a pretty well-researched fact. So with a total range of 1200 - 1500 meters, I fully expect 800 meters to be feasible and lethal. Of course it will be difficult to hit a target dead center but as said before, the point was to keep the enemy away from the minimum field artillery range and the artillery unit themselves.

The 800 meter 'french helmet' story can be found in the official LP08 manual issued by the German army:

Translation from the manual (1917):
Performance of the Lange Pistole 08.

Due to the high rate of fire and the ease with which it can be handled, the pistol, in combined firing, and with enough ammunition available can be used effectively even against head sized targets up to 600 meters. Between 600 and 800 meters, with the correctly set sights, results can still be expected.

Up to 200 meters, every target can be hit with result in single fire.

At 800 meters a horse skull and a french steel helmet will be shot through.

biffJ.

Interesting! I never thought about a bullet that's about as long as it is wide. So if it starts a subsonic tumble, the trajectory isn't going to change that much! Almost like a musket ball.

FN

Is that a single shot, or two separate shots???

Reminds me of the story of Jesse James, when he rode with Quantrill's raiders, lining Union soldiers up against a tree to see how many could be penetrated with one rifle shot...

two separate shots :)

(not a lot of horses wore french helmets, back then anyway, lol)

The 9mm bullets don't tumble at that range, they are still going straight even though they drop below the speed of sound at less than 100yds. If simply dropping below the speed of sound caused tumbling than the effective range of the 9mm parabellum would be 80-90 yds. The difference in the effect of passing the sound barrier between these short bullets and the longer rifle bullets is the center of gravity's location in relation to the aerodynamic stability of the bullet. With the short pistol bullets the CG is pretty close to the aerodynamic center and therefore the bullet does not lose much in the way of stability as the shockwave moves forward due to the slowing of the bullet. In the long rifle bullets the CG is frequently quite a way back on the bullet and the CG always wants to be in front. The only thing keeping these bullets going straight is the spin and aerodynamics. As the bullet slows down the shock wave moves forward and that destabilizes the bullet as it moves in front of the CG. This doesn't always lead to tumbling but can cause wobble or nutation as its called. That is what disrupts the accuracy, not tumbling. Sorry for hijacking the thread with ballistics but it is pertinent.....

Frank