Why did my front sight mounting become out of level?

I'm hoping someone can give me an idea where I went wrong not counting the fact that I tried to do it myself.

I started the day trying to mount a ramp and globe front sight onto a CZ 455 American barreled action. I purchased a new Forster Universal Sight Mounting Jig, new drill bits (7/64 & #31), drill stops, & 6-48 bottom tap from McMaster Carr, a Williams Shorty Ramp & a globe front sight from Lee Shaver Gunsmithing. I started by reading the directions, leveled the jig on a firm work surface and checked level on the two v-blocks and overarm, all appeared to be level in regards to each other and checked center between the overarm and both v-blocks. I marked an appropriate location for the mounting screw hole on the barrel and using the provided center lined up the mark and leveled the barrel in both x & z axis using the barrel length and flat top of the action. Working slowly, carefully and using the included drill guides I drilled both a pilot and tap diameter hole. Since the hole was too shallow to use a plug tap, I carefully tapped the hole with a bottom tap using the included tap guide, gentle pressure and making sure that I cleared chips frequently. Once the hole was tapped and cleared of chips, sprayed with degreaser and allowed to dry, I tested the screw and ramp to make sure that everything fit snug which it did. After cleaning the barrel & underneath of the ramp, I applied a small amount of blue loctite to the screw and tightened the ramp down. With the barreled action removed from the jig and now clamped in a padded vise, I drifted on the globe sight and feeling good about what I had accomplished.

I then mounted the action in the stock and shouldered the rifle. It looked like the sight was off so I returned the barrel of the rifle to the padded vise and leveled the action. Then, looking thru the globe I took note of the bubble on the spirit level inside the globe...it was off 1/2 bubble. I removed the spirit level from the sight and placed it on the receiver....it showed level. I reversed the spirit level in the sight as suggested by Mr. Shaver with no change...still 1/2 bubble off. I removed the front sight and placed the spirit level in the ramp dovetail leaving my torpedo level on the receiver for reference, again 1/2 bubble off.

What the hell happened?

Orphanbrg said:

I'm hoping someone can give me an idea where I went wrong not counting the fact that I tried to do it myself.

I started the day trying to mount a ramp and globe front sight onto a CZ 455 American barreled action. I purchased a new Forster Universal Sight Mounting Jig, new drill bits (7/64 & #31), drill stops, & 6-48 bottom tap from McMaster Carr, a Williams Shorty Ramp & a globe front sight from Lee Shaver Gunsmithing. I started by reading the directions, leveled the jig on a firm work surface and checked level on the two v-blocks and overarm, all appeared to be level in regards to each other and checked center between the overarm and both v-blocks. I marked an appropriate location for the mounting screw hole on the barrel and using the provided center lined up the mark and leveled the barrel in both x & z axis using the barrel length and flat top of the action. Working slowly, carefully and using the included drill guides I drilled both a pilot and tap diameter hole. Since the hole was too shallow to use a plug tap, I carefully tapped the hole with a bottom tap using the included tap guide, gentle pressure and making sure that I cleared chips frequently. Once the hole was tapped and cleared of chips, sprayed with degreaser and allowed to dry, I tested the screw and ramp to make sure that everything fit snug which it did. After cleaning the barrel & underneath of the ramp, I applied a small amount of blue loctite to the screw and tightened the ramp down. With the barreled action removed from the jig and now clamped in a padded vise, I drifted on the globe sight and feeling good about what I had accomplished.

I then mounted the action in the stock and shouldered the rifle. It looked like the sight was off so I returned the barrel of the rifle to the padded vise and leveled the action. Then, looking thru the globe I took note of the bubble on the spirit level inside the globe...it was off 1/2 bubble. I removed the spirit level from the sight and placed it on the receiver....it showed level. I reversed the spirit level in the sight as suggested by Mr. Shaver with no change...still 1/2 bubble off. I removed the front sight and placed the spirit level in the ramp dovetail leaving my torpedo level on the receiver for reference, again 1/2 bubble off.

What the hell happened?

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I have no idea what went wrong on the sight, but I know that post title is wrong and will get this post locked.

moonlight machine said:

I have no idea what went wrong on the sight, but I know that post title is wrong and will get this post locked.

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Nothing I can do about it now....guess it's the second screw up of the day

If the new title is not sufficiently detailed, please suggest a better one.

Orphanbrg said:

What the hell happened?

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Might be your levels ALL have errors? None were mentioned as uber-accurate ones of the sort some of us traffic in for machine-tool assessment.

Before chasing it further - as you SEEM to have done all the right things?

How about going off and punching some holes to see if you can effectively zero the rig in spite of what looks to be a minor tragedy at the moment.

That should at least add to your knowledge base as to the magnitude of the effect. Or lack of effect.

I'm not particularly familiar with the rifle you did, or all the tooling you used. But if I'm understanding you, the rifle was not completely assembled when sight was installed.

For me, on rifles, I want to install the front sight last, on a complete rifle. A rear sight with wind-age adjust is not as noticeable, but a canted front sight can be an eye sore.

A problem that happens often is, as you tighten everything down, be it screws, pins or what ever, that they will slightly twist, or change location of part slightly.

I do front sight last, as barrel will be locked into reciever and any twist or turn is done on that end. Then Besides which ever leveling tools, I use four carpenter squares to double check my leveling. These kind of squares stand up, with at least one flat edge. On a flat bench, I use two squares to straddle receiver or stock snuggly. Then the other two squares to straddle front sight, front post should be dead in the middle of the two squares. Double check, with levelers, but I usually trust sight being square to receiver more. Etch small aligning marks on barrel and front sight. Drill or pin after.

Sell that Forster on Ebay and get someone to help who has a milling machine. I do all my sights on one. Those Forsters have caused a lot of canted sights

texasgunsmith said:

I use four carpenter squares to double check my leveling. These kind of squares stand up, with at least one flat edge. On a flat bench, I use two squares to straddle receiver or stock snuggly. Then the other two squares to straddle front sight, front post should be dead in the middle of the two squares. Double check, with levelers, but I usually trust sight being square to receiver more. Etch small aligning marks on barrel and front sight. Drill or pin after.

View attachment 225249

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That square resembles two brand-new "Empire" made in USA I just last week bought - sold packaged as a pair - from Lowes.

News flash. They are NOT "square".

A pair being easy to face to each other, new, no dings yet, I first tried them against each other on the glass kitchen stovetop 'coz it was handy. Obvious divergence, not just a teeny-tiny bit.

OK - could be the cooktop. Next went down to the shop, confirmed it on a better surface.

Herman Grade A surface plate.

Check yours. Hope you have better luck.

First, thanks for the input. Second, thanks to whomever changed the title of this post.

From the responses some clarification may be in order.

While I am aware that the tools I am working with may seem to some sub-standard they are all I have at the moment and maybe this will be an answer to that particular error.

I was using a Stabila 11901 Magnetic pocket level and while I do own two, I've learned that they are slightly off when compared to each other so to that end I only use one at a time. It stands to reason (in my mind anyway) that if I level the jig using a specific level and use that same level throughout the project without exception there should be continuity in plane. Much the same in cabinet making...you don't change tape measures in the middle of a project.

The base rifle was manufactured with sights, a military style ladder mounted at the rear of the barrel and a hooded blade on the front. Since I wanted the rifle set up for an iron sight target rifle and I didn't want to monkey with trying to remove the factory sights from a perfectly good barrel, I chose to replace it with a factory barrel of a different style, one that had no sights installed. A Williams FP receiver peep sight would take the place of the ladder and a Lee Shaver P-H Globe sight would now act as the front.

The barrel system on the CZ-455 is meant to be removable, interchangeable and is held in place using two grub screws that seat the barrel into the receiver at opposing, roughly 45 degree compound angles. The with the new barrel properly torqued in the receiver, the complete barreled action (minus the stock of course) was clamped into the jig. Since the receiver on the CZ-455 is round I don't think straddling the action with carpenter squares would have been much help. Using the machined flat surface of the dovetailed receiver as a reference, I leveled the roll in the action and then leveled the pitch in the barrel until it was level and parallel with the overarm. I rechecked roll and pitch several times as I slowly alternately tightened the two v-block clamps.

My only thought would be that when I remounted the magazine well and the stock, the force of those two forward screws which have access to the underside of the barrel somehow pushed things out of alignment. I'll have to disassemble the rifle to where I started and recheck at that point.

A milling machine would have been the way to go and nothing would give me greater pleasure than to add a milling machine to my stable of tools. There are some issues to that though. First is the pocket book which can eventually be overcome. The second is the low clearance of my basement, roughly 6-1/2'-7' to the bottom of the joists. Been looking for a good used Millrite but always seem to miss them in my area.

Orphanbrg said:

A milling machine would have been the way to go and nothing would give me greater pleasure than to add a milling machine to my stable of tools. There are some issues to that though. First is the pocket book which can eventually be overcome. The second is the low clearance of my basement, roughly 6-1/2'-7' to the bottom of the joists. Been looking for a good used Millrite but always seem to miss them in my area.

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Again, it "seems as if" you did all the right things, but with marginal tools. Poor tools are serious time-wasters - any tool, any trade.

GOOD levels are cheap enough. You don't need a 12" or 15" Starret, B&S, Vis, Lufkin, or Scherr.

I also have a pair of short, Chinese made precision "block" levels that are astonishing accurate for their modest price. Should be a good fit to what you are doing. japanese, French or Swiss ones even more so.

Milling machine? Low overhead? You don't need a vertical.

A few hundred bucks will put a Burke # 4 horizontal into that tight budget and space. Not a lot more, a Nichols or even a Hardinge TU or TM. There are easily a dozen OTHER makes of small Horizontals - antiques are fine - that can serve well under a low overhead.

Get YOUR head and an angle plate or three around the idea of the workplane being 90-degrees rotated, and the cuts go easily as nicely as a too-tall and less rigid Millright vertical or other BirdPort clone. Not as if you had to fab valve-bodies for a dual-range Hydramatic mashmission.

And I still say you need to take that rig out and go punch some holes in paper.

Firearms are simple critters. They can be chock full of errors. So long as... those errors are stable and consistent - can put one round after another in the same "wrong place"?

Shooter adjusts, does a helluva job with it. Regardless.

I made this one as other jigs were not big enough nor accurate enough for my work. I silver solder the sight bases.

Remember, all sighting must be "Square and Plumb" to the bottom flat of the receiver. We are talking mauser type receivers, not the round tube things.

All mating surfaces are machined, including the bottom of the base, so the jig may be clamped to the milling machine table.





The V blocks have a round shank and telescope in the base blocks and have clamping setscrews. The bores for the V block shanks were bored with a boring head after the base blocks were attached to the long base plate.



Not quite square as you can see below, just a mock up for the photo.





Things to keep in mind:

A drill press table is not necessarily square to the spindle centerline. Swing a dial indicator and do a tram check.

Never pound a dovetail sight into the ramp unless you are certain you will not displace the sight base. Best to use a pusher like the Williams tool.



Even on a milling machine, tram in the spindle to the table. I check the tram on my vertical mill often. And the table is 54 inches long, large enough for any barreled action without having to move and reset up the assembly.

Below, showing the way I set up in the milling machine when not using the jig. Note the tap wrench with pilot in the spindle, the wrench telescopes on the pilot. There was a parallel under the receiver flat when aligning, and the assembly is clamped to the table. Drill and tap in one setup after aligning the barreled action to the table.



Note in all photos I am mechanically aligning the sight base to the bottom of the receiver. Levels are not accurate!

One thing that bothers me about the "store bought jig":

Are the bushings in the overarm absolutely square to the pad the receiver is mounted on? How about "stacked tolerances" in all the assembly pieces? Things to keep one awake at night.

thermite said:

Again, it "seems as if" you did all the right things, but with marginal tools. Poor tools are serious time-wasters - any tool, any trade.

GOOD levels are cheap enough. You don't need a 12" or 15" Starret, B&S, Vis, Lufkin, or Scherr.

I also have a pair of short, Chinese made precision "block" levels that are astonishing accurate for their modest price. Should be a good fit to what you are doing. japanese, French or Swiss ones even more so.

Milling machine? Low overhead? You don't need a vertical.

A few hundred bucks will put a Burke # 4 horizontal into that tight budget and space. Not a lot more, a Nichols or even a Hardinge TU or TM. There are easily a dozen OTHER makes of small Horizontals - antiques are fine - that can serve well under a low overhead.

Get YOUR head and an angle plate or three around the idea of the workplane being 90-degrees rotated, and the cuts go easily as nicely as a too-tall and less rigid Millright vertical or other BirdPort clone. Not as if you had to fab valve-bodies for a dual-range Hydramatic mashmission.

And I still say you need to take that rig out and go punch some holes in paper.

Firearms are simple critters. They can be chock full of errors. So long as... those errors are stable and consistent - can put one round after another in the same "wrong place"?

Shooter adjusts, does a helluva job with it. Regardless.

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Good Advice.

My little Burke below. Has a vertical head also. I rarely use it as mostly the big Vertical mill does the work. Photo taken when I was making the V blocks for the sight ramp jig in the above post. Variable speed DC motor.

SilveradoHauler said:

Good Advice.

My little Burke below. Has a vertical head also. I rarely use it as mostly the big Vertical mill does the work. Photo taken when I was making the V blocks for the sight ramp jig in the above post. Variable speed DC motor.

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I see an idea or two in your foto I may shamelessly steal when I get the damned roof fixed and get back to my "iron" projectss.

Mine is a "stalled" conversion to T.B. Woods by Baldor-Mexico Dee Cee motor. NOS @ $200 shipping included, ex Left Coast. KB-Penta controller is brand-new.

Dee Cee is a good fit, given how scarce undamaged Master, Century/Lima integrally geared-head motors have gone.

DC motors are a hoot. Zero to max speed by turning a knob. And high torque at low RPM. I also have a DC on the big vertical mill (2 HP) and a 2 HP on one of my lathes.



The black box on the wall is the DC Power Supply.



Forward, Reverse, Start/Stop, Jog, Speed Control

The OP used a level that was known to not be on, then compared it to the level in the sight. An accurate level is a must for this job, assuming the level in the sight is accurate. It should be checked before starting. If the site level and the level used for setup agree, then you are ready to start setup.

ulav8r said:

The OP used a level that was known to not be on, then compared it to the level in the sight.

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Stop right there. Setup "slippage" and creep got you. Poor tools, poor practices, poor results. Having used both Forster jig and bridgeport, and nowadays both at same time, careful setup is a must. Both will give good results if you pay close attention when you are aligning things.

kendog said:

Stop right there. Setup "slippage" and creep got you. Poor tools, poor practices, poor results. Having used both Forster jig and bridgeport, and nowadays both at same time, careful setup is a must. Both will give good results if you pay close attention when you are aligning things.

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While I admit that the level I used may not have been up to snuff, the barrelled action was parallel to the jig in both roll and pitch before, during and after the drilling and tapping operation. I know because I made careful note of it's position throughout the process. In the future, in the absence of a better level, I would do well to use the level located in the soon to be mounted sight.

Now you have me looking at horizontal mills and while I will admit that I know next to nothing about vertical mills short of a year @ the local Voc-Tech, I know absolutely nothing at all about a horizontal mill.

What am I looking for in a good mill and what tooling is an absolute necessity when considering a purchase? Point of fact, there is a listing in the local classifieds for a Nichols. It looks to be a standard model with a vice and some tooling. The condition from the photos suggest that it is slightly used and/or very well taken care of. What would be an appropriate dollar figure for something like this?

Orphanbrg said:

...there is a listing in the local classifieds for a Nichols. It looks to be a standard model with a vice and some tooling. The condition from the photos suggest that it is slightly used and/or very well taken care of. What would be an appropriate dollar figure for something like this?

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The Nichols models with the sliding head, ditto similar build-quality but scarcer "Diamond" (also Frey tie-in) are about the most all-round useful small horizontals out there.

IF.. it still has a working integrally geared-head Master, Century, or Lima motor, I'd think it worth serious coin vs a plain Burke or the like (~ $300-$600) without the sliding head.

Horizontals run fairly low RPM but high-torque spindle speeds for anything but small endmills.

If no OEM geared motor, you would want a 3-P + VFD motor of around 2 or 3 HP, ELSE a DC motor and DC Drive of 1 to 2 HP (more useable torque, DC usually delivers).

Either of those are dead-easy to integrate to common belt drives or even less-common chain drives.

Tooling is usually #9 B&S taper with a great deal more grip and HP capacity than a BirdPort's most common - the R8. 30 or 40 taper would be cheaper and easier to tool-up. R8 on the torque a Horizontal works with, a borderline disaster. It is over-stressed for a lot of the work even a BeePee vertical is asked to handle. Same-again 4C and 5C - the unfortunate limitation of Hardinge TU or TM. "All players" are far the better mills with 30 or 40 taper OEM spindles or conversions.

#9 B&S collets can still be had new (H&H Industrial). Milling-cutter holders are stouter, still "out there", but used.

Putting an ER, TG, or one of the "Quick Change" adapters (PDQ-Marlin "VS" series here) onto the spindle lets you grab most anything within the mill's capacity range.

2CW (Burke B-100-4 AKA #4, "Quartet" with #9 B&S on its vertical spindle.)

now the short answer to your question is because it can.
even with a jig drill bits wander