M14 Forum

art7 · January 1st, 2012, 10:41 PM

I want to get some ideas flowing about rear sight improvements. I took a stab at this a few weeks ago, when I came up with the idea of putting foam rubber blocks in the sight to bias the windage threads. It seems to work, but I have a few other ideas I want to bounce off people, and would love Gus to chime in.

Can you pin a rear sight? I'm talking horizontal pins. You'd have to drill holes in the 'ears' of the receiver, which is scary for an expensive part. However the AR guys are doing this with success, and it is NRA and CMP legal. I think there is enough meat on the carriage. I own a rear half of a TRW receiver that was chopped, so I can experiment, but I wanted to get input first.

Thoughts?

Art

Gus Fisher · January 2nd, 2012, 01:09 AM

Art,

I don't think there is room anywhere on the RS base to drill holes for horizontal pins large enough to do any good. Maybe just forward of the hole for the pinion and at the bottom of the RS base, but I don't think so.

However, I think the pins in AR's are vertical and by the fact they are in two places, they hold the base from slipping side to side. Scroll just a bit down the following page to see how it is done.

http://www.whiteoakprecision.com/uppers-service.htm

art7 · January 2nd, 2012, 06:00 AM

Understood how the AR pinning is different and vertical, and this would not deliver all the benefits that AR pinning would. But if you could get one or better two pins in the M14, it would keep the carriage square in terms of side-side twisting. There would still be lash between the aperture and the carriage that I have not accounted for yet.

Art

Gus Fisher · January 2nd, 2012, 06:22 AM

I just don't see any spot you could drill through both sides of the receiver and into the RS base to get a horizontal pin in it. Of course, the pinion could mess up some of that alignment as it may not fit once you pinned the RS base that way.

Phil McGrath · January 2nd, 2012, 08:23 PM

I have seen one rear sight base drilled for a guide rod, the guide rod fit thru the RS base and fit INSIDE the RS pocket, a pair of small springs one on each side kept slight preasure on the base.

How the rear sight tracked for windage before/after the mod or how repeteable the windage was, I don't know.

BDH · January 2nd, 2012, 09:21 PM

Seems like it couldn't be used for competition due to altering appearance. But if you don't compete with it, who cares.
Bruce

Bamban · January 2nd, 2012, 09:49 PM

Art,

I went through a lot of work to get the sight on one of my M1As work just right. What I found out the base thread matching to the windage knob thread is not the best, slop is there, backlash. While assembled, put a dial indicator and wiggle the windage knob you can see the dial moved till it settles. I think even if you put the parallel guide rods, you still have to address the thread slop. On some M1A sights you can't go back and forth 1 click and expect it to move. I heard people say only move in one direction, say if you want 1 click L, go 2 clicks R, then 3 L, or 1 R, then 2 L. Whatever they do I will get lost with the process.

On this particular M1A I sent the base and windage knob to Gary LaValley, the principal of Phoenix Precision Match Sights. He bushed the base and re-threaded it to precisely match the threads on the windage knob. He then milled off the 4 big detents on the sight and cut 8 equidistant detents for ball and detent set to using the 32 TPI. Gary has a CNC Mill dedicated to cutting threads

I like what the concept of rods and springs inside the RS pocket mentioned by Phil.

Here is my input.

Assuming you have enough meat to cut precision holes, is it feasible to insert linear bearings through the holes for the rods to ride on. Instead of using one rod per hole, use 2 and insert a compression spring in between them. This will allow for drop in base that snaps in between the walls of the RS pocket without punching precise holes through the the receiver sight ears for the rods. The spring loaded rods make up for the lousy tolerance of the RS pocket.

Or maybe one rod all the way and trimmed/filed to length and in the other hole the internally spring loaded rods

Maybe the linear bearing are not needed, just precise holes.

While you are at it, figure out a way to negate the need for the sight cover function of providing downward pressure on the elevator rack down against the slot in the RS base. The sight cover will just be sitting there as an artifact satisfying the NO external mod rule.

win308 · February 10th, 2012, 07:43 PM

The only thing I have seen is a blind hole drilled in the rear sight base...similar to Phil's idea, and then a coil spring about the size of an ejector spring is inserted into the hole. When the rear sight is assembled, the spring exerts a constant pressure on the base pushing to the left. Every click to move the sight to the right has to fight the compression of the spring. You need two clicks left windage, you go six left and then come back four.

Bamban · February 10th, 2012, 08:57 PM

Quote:

Originally Posted by win308

The only thing I have seen is a blind hole drilled in the rear sight base...similar to Phil's idea, and then a coil spring about the size of an ejector spring is inserted into the hole. When the rear sight is assembled, the spring exerts a constant pressure on the base pushing to the left. Every click to move the sight to the right has to fight the compression of the spring. You need two clicks left windage, you go six left and then come back four.

I had one similar installed by C Fowler in tripled lugged M1. I got real confused in fishtailing wind I ditched the spring.