It has become clear that the scope base on the Reidl is causing the "not hitting where you aim" issues. First the Lyman ran out of both elevation and windage while still printing approximately 6" high and 6" right. Next, the Simmons ran out of windage "on", but also ran out of elevation while still printing 4.5" high at 35 yd. The rings are Burris, and I assume that the base is too. Regardless, something has to be 'done' about the base.

I removed the scope and the base.









The barrel is 1.139" in diameter at the rear hole, 1.125" at the middle hole, and 0.865" at the front hole.

The hole spacing is:
3.30" from the rearmost hole to the front hole.
0.80" from the rearmost hole to the middle hole.
Which means 2.50" from the middle hole to the front hole.

I have radius guage set, and the radius of the front of the base is .4375" (7/16ths). Unfortunately, the set only goes to .5000" radius (1 inch diameter), so I couldn't get an exact measurement on the radius of the rear of the base. I will assume it is 1.139"/2 or 0.5695" because the rear of the base fits the barrel pretty well. What that means is that I would need to get a mill cutter of diameter 1.139-ish if I wanted to mill the rear of the base 'shallower'. I probably do. Here's why:

The thickness of the base behind the rear screw hole is 0.232".
The thickness of the base at the front of the middle screw hole 0.205". That means  a taper of approximately .027" per inch. The change in diameter of the barrel over that same inch is 1.139 - 1.125 = 0.014". So the barrel is getting smaller between the rearmost screw and the middle screw AND the base is 'thinning' as well. Combined that "tilts" the base down-in-front by about 0.041" inches. That's a lot! If I remember correctly, moving a sight 0.001 inches at the gun moves bullet impact by 1 inch at the target. (Don't quote me on that though, I'm not 100% sure I'm remembering those numbers correctly.) If I have those relationships correct, that's 41" of "up" at the target that the base is "adding".

The front of the base is uniformly 0.333" thick. The barrel is 0.865" in diameter at the front screw. Therefore, adding the thickness of the base to the HALF the diameter of the barrel we get 0.333 + 0.4325 = 0.7655" for the height of the top of the base above the centerline of the bore.

The rear of the base is 0.232" thick. The barrel is 1.139" in diameter. Half the diameter is 0.5695". Therefore the height of the rear of the base above the midline of the bore is 0.232 + 0.5695 = 0.8015".

Now, if the height of the rear is 0.8015 and the height of the front is 0.7655, then there is 0.8015 - 0.7655 = 0.036" of "down-slope" to the base. That is 36" of "up" at the target.

So, using only the measurements of the base I get 41" of elevation ADDED by the base, and using both the taper of the base and the taper of the barrel I get 36" of elevation ADDED by the base. Either way, that's too much tilt in the base. I think I need to take 0.036-ish off of the rear of the base.

Paul

In view of the problem with getting a milling cutter that size, I would likely be looking at shim stock, unless I am missing something.

I'm sure that you have people that can sharpen milling cutter over there...

Shimming is definitely the easiest solution, I think. Still, it is possible to set up the dividing head to rotate on a specific radius relative to the center-line of the quill. Theoretically, the diameter of the mill cutter would be immaterial as long as it was less than the diameter of the radius you were trying to cut. Holding that base in the dividing head might require some 'gymnastics' though.

Another advantage to shimming is that it isn't "one time" permanent. If the 30 to 40 thou of adjustment was 'off', removing or adding shims is considerably less painful than replacing the base or ending up shimming anyway.

Paul

Quote from: j0e_bl0ggs;141275I'm sure that you have people that can sharpen milling cutter over there...

Sadly, I'm not sure that statement is true for the state of Alaska.

Paul

I think my "0.001 at the gun equals 1 inch at 100 yds" was wrong. "Doing the math", if one minute of an angle equals approximately ONE inch at 100 yd, and TWO inches at 200 yd, then it equals approximately 1, one-hundredth of an inch (1/100") at the gun. So the above corrections of 41 and 36 should be divided by 10, resulting in 4.1 or 3.6. But, the measurements of 41 thou or 36 thou are still correct, they just represent 4.1 and 3.6 "mils". Which is why I got confused, because "milli" is the prefix for "thousandths". However, in this case it stands for milliradian.

Paul

Quote from: gitano;141277Sadly, I'm not sure that statement is true for the state of Alaska.

Paul

Don't believe that for a second, a remote place would deffo have a tool n cutter grinder, failing that I'll get one ground here and send it to you...


BTW no need of rad gauges, diameter of barrel under fitting will do...

QuoteDon't believe that for a second,

I might take that bet.

QuoteBTW no need of rad gauges, diameter of barrel under fitting will do...

Not if the radius of the base is different than the radius of the barrel. Looking and "wiggling", I'm not convinced that they are the same. While I have the diameter of the barrel at any give point - with screw holes easy landmarks for measuring - measuring inside radii is considerably more difficult without gauges.

Paul

Then if rad on base is different to the barrel rad the sight base has not been fitted correctly.

How about you take the base off the gun mount rings to it mount an old pos scope to the rings hold old scope in a vice and turn a piece of wood to the radius you need cover with sandpaper and away you go.

A one inch shaft would work instead of the old scope.

Better to just do it 'properly' seeing that the machine tools are available.

That process crossed my mind, farmboy. The issue with that - not a 'deal killer', but an added complication - is the slight taper from the rear screw hole to the front - about 0.015" over that inch. Hand fitting with sandpaper is certainly a way to 'sneak up' on the fit and get it right on, but also certainly tedious.

What I'm going to do is shim the front of the base about 40 thou/1 mm, remount the Lyman scope, and check the sighting. If that amount of shimming solves the problem of the scope running out of elevation adjustment, I'll remove the shim(s) and decide on a method of modifying the base.

Paul

Need to have a sense of humour to sand off 40 thou....

Quote from: j0e_bl0ggs;141289Need to have a sense of humour to sand off 40 thou....

of steel.

Paul