Windage adjustment on 1917

[NuJudge]

I shot my 1917 today with a handload known for shooting well in any .30-'06 that will shoot at all, and at 50 yards I got a group about 6 inches right and about 3 inches low from point of aim. The first shot on a clean barrel was about 3 inches below the point of aim.

I know I need to move the front sight right, but can anybody tell me how far?

[45B20]

NuJudge
Changes to front Sight to be made to move the group a specific distance:

Sight radius, times how much you wish the group to move, divided by the range, equals the change in the horizontal position you must make to the front sight. All Measurements are in inches. This also works for the up/down
movement of the group.

Remember: the direction the front sight is moved is in the opposite direction you wish the group to move on the target. That is: move the front sight to left, group moves to the right. Move the front sight down and the group moves up.

45B20

[NuJudge]

Here are calculations for changing elevation with the M1917:
http://www.nicolausassociates.com/PDF/M1917SightHeightCalcs.pdf

I was wondering if someone had gone to the trouble for windage. Looking at the elevation calculation math, I believe the same formula applies for windage.

[jamie5070]

Someone mentioned checking the bedding of the action and barrel before moving the front sight to make sure that there wasn't a high spot that was throwng things off. I recently had one rebarreled and it appears to be high and right. I haven't checked things out since I put a few rounds through it.
john

[Patrick Chadwick]

I agree with jamie 5070. 6 inches off-beam horizontally at 50 yards is way too much. The rifle would possibly/probably have originally been adjusted by the unit armorer and the front sight staked Take a careful look at the front of the sight block and check if you can see a small dimple (the stake mark). If so, then you can be sure that the rifle was OK, once upon a time, and something has changed. A plausibility check - the blade should not be more than about +/- 1 mm off the center line.

As the M1917 has a sight radius of 80 cm, the blade movement to give 6" at 50 yards would be 1/300 of 80 cm.

That is a grotesque 2.7 mm, more than 1/10".

So I think the bedding must be completely lop-sided. Don't forget, the wood is now 90 years old, and may have warped to press heavily on one side of the barrel. Or (don't laugh, I have experienced this) the trigger guard screws are loose!

Simply loosen the barrel bands and slide them forwards, so you can remove the handguards. Try sliding a piece of card up and down the barrel channel, between the barrel and the wood. If the resistance on one side is different to the other side, then the woodwork is warped.

Patrick

[musketshooter]

A handload that "shoots well in anything" may not shoot well in a 5 groove left hand twist rifle. I would try some military issue 150 grain ammo before adjusting the sight. You may have to taylor a new load for that rifle.

[NuJudge]

I shot a bunch of LC69 in this rifle, and it really does not like it. Huge groups, but not as far off center.

[Curt]

I have had luck with 1917's by grasping the top of the stock near the muzzle,put your thumb over the muzzle and see if it wiggles.If it does use a thin wood shim loosen the front band slide it under the barrel and tighten it back down.helps wandering zero's and loose groups, probally won't fix this problem though.

[Jim K]

With the older rifles, we can't overlook the possibility of a bent barrel. A bend is easy to detect, simply look through the bore from the back; a shadow should tell you if the barrel is bent and about how much. Some gunsmiths are set up to correct the problem, others are not. I don't think of it as DIY proposition.

Jim

[Dan Wilson]

If your shooting the LC that the CMP sold, its all delinked machine gun ammo and is not standard M2 ball spec. It tends to run low on velocity and accuracy.

Dan

[Timmer]

To answer your question I believe you will find that a 0.08" movement to the right will move your group 1" to the left at 100 yards. I used a micrometer to sight in my P1917 Eddystone. I had to move my front sight to the right 0.16" (sixteen hundredths of an inch) to put my rifle into the center of the black. I shoot handloads that average 2,720 fps using a 152 grain FMJ bullet. The rifle originally shot groups with the 5 shot groups center 2"s to the right of the targets center. After I moved the front sight and verified the movement using the micrometer the next 5 shot group was centered on the target. The target was an 8" bullseye, shot using a center hold.