A little gunsmithing on a hot afternoon

[Yooper]

Going down one of my rabbit holes just to satisfy my curiosity. Just for the heck of it, I put my Rem 700 action with the scope rings installed on the mill and checked them for parallel and alignment. What I found out was shocking! Nothing with the rings was even close to be in line. The picatinny rail had a twist, the rings were out of alignment over .040" and not parallel with the bore. So on a hot muggy afternoon I turn on the AC begin to mill my own rail while it is mounted on the receiver.

One of the challenges on the receiver is two different radii and two different heights. Thank god for a cad program to help me get that figured out!

I wanted the scope tube to bisect the bore so I measured the scope mount after getting it to full profile on one side and measure the center of the rings. Got the number and finished milling it to spec but in the end I was still .034" from perfect center. Should have paid better attention in geometry back in the school days. But the windage turret will dial that out and I am happy that the mount is within half a thou from ring to ring. No binding on this scope! Also corner rounded the edges of the mount rings to keep from digging into the scope tube.

You can see the amount of offset to try and center the tube but it really should have been a bit more.

 

[McMXi]

the rings were out of alignment over .040"

.040"? In which direction? Vertically, horizontally, or some combination of each?

 

[Yooper]

.040"? In which direction? Vertically, horizontally, or some combination of each?

Horizontally.

 

[ken erickson]

.040"? In which direction? Vertically, horizontally, or some combination of each?

I also am interested in which direction.

I was warranty repair for Remington from 1990 to 2002 and do not think I had encountered improper scope base mounting holes or receiver contours, at least to that degree.

Curious to know what that grind spot in the back face of the receiver that I highlighted with white arrow is and what is the over all history of your receiver? Factory base holes and factory contours?

When you measured the out of alignment are you measuring off the bolt bore of the receiver or outside of receiver?

Wondering also how you determined the proper "alignment" of the receiver in your milling vice. 700 receivers have very little flat horizontal surfaces to index off of as you know.

Please take my question in the context of me finding this topic interesting and not a criticism of your setup etc.

 

[RCW]

Oh man, I’m always so intrigued by the knowledge and skills you guys have….

@Yooper has posted many projects over the years and I’ve enjoyed them all.

There’s so many others with great talent that have posted projects as well.

You guys know who you are.

Wish I had 10% of your abilities.

 

[#40Fan]

OP, do you own a lathe? If so, I'd turn and thread a stub that you could screw your receiver onto. Lock the spindle down and then recheck all of your work from the beginning.

 

[Yooper]

OP, do you own a lathe? If so, I'd turn and thread a stub that you could screw your receiver onto. Lock the spindle down and then recheck all of your work from the beginning.

I actually have three lathes. I think I know what you’re suggesting and if I have it right, I can accomplish the same thing in the mill. (Which I just finished up this afternoon) Off to the range tomorrow morning and commence with the testing.

This all started when I watched a video on scope mounting. I started thinking about all the things we assume are correct. Did the manufacturer align the reticle with the scope base? Is the rail straight? Are the rings or mount parallel with the rail and then is the rail parallel with the bore of the barrel? If I would have mounted the scope in the original rings it would have tried to bend the scope tube in a ‘U’ shape. Of course I am exaggerating but there is a bunch of glass lenses in a scope and I don’t think stressing the tube would be good.

 

[NCL4701]

Since there are people here way, way smarter than I am on this subject, I’m going to ask a stupid question (or two).


If the rings aren’t lined up with each other such that they’re trying to bend the scope tube (inducing torque on the scope tube): isn’t that usually remedied by lapping the rings unless it’s so severe as to constitute a defect?

So long as the scope tube isn’t being bent, if the tube isn’t quite parallel with the bore isn’t that usually addressed by adjusting windage and elevation in the normal sighting in process?

I don’t have shots over about 300 yards so maybe I’m just not used to the higher level of precision required for longer shots.

 

[skeets]

Thats interesting, but since I lost everything in that boating accident I dont have anything to fool with

 

[McMXi]

If the rings aren’t lined up with each other such that they’re trying to bend the scope tube (inducing torque on the scope tube): isn’t that usually remedied by lapping the rings unless it’s so severe as to constitute a defect?

So long as the scope tube isn’t being bent, if the tube isn’t quite parallel with the bore isn’t that usually addressed by adjusting windage and elevation in the normal sighting in process?

Yes, lapping rings is a way to improve the fit between the rings and the scope tube. In a perfect world you want 100% contact between the rings and the scope tube without plastic deformation of the tube, and just the smallest amount of elastic deformation to prevent the scope from moving in the rings due to recoil.

And yes again. The misalignment is corrected by zeroing the scope to correct for any error, and ideally the corrected position of the reticle for zero is close to the center of the adjustment range (horizontal). Vertical zero is a bit more involved and perhaps more forgiving. There are many Picatinny rails and even some scope mounts with a built in cant of 10, 20 or 30 MOA to bias the range of vertical adjustment of the reticle in favor of providing more movement of the reticle downward to compensate for bullet drop at greater distances.

If the rail or scope base/mount isn't canted, you might only have half of the total vertical adjustment available to compensate for bullet drop.

 

[Runs With Scissors]

Outstanding work sir!

Have you done any "blueprinting" work on the gun?

I only have one Remington 700 action, and was thinking about making it my "first try" at blueprinting.

Out of curiosity, what caliber is it?

 

[Yooper]

I also am interested in which direction.

I was warranty repair for Remington from 1990 to 2002 and do not think I had encountered improper scope base mounting holes or receiver contours, at least to that degree.

Curious to know what that grind spot in the back face of the receiver that I highlighted with white arrow is and what is the over all history of your receiver? Factory base holes and factory contours?

When you measured the out of alignment are you measuring off the bolt bore of the receiver or outside of receiver?

Wondering also how you determined the proper "alignment" of the receiver in your milling vice. 700 receivers have very little flat horizontal surfaces to index off of as you know.

Please take my question in the context of me finding this topic interesting and not a criticism of your setup etc.

View attachment 157673

Not sure what that is about but I bought this used and then blue printed the action and installed a new barrel.
There is no issue with the receiver. The issues have been with the rails and rings/mounts. As to how I set this up in the mill I will try my best to explain: first I clamped the receiver in the vise and using an edge finder established the center of the receiver. Then locking the table on center I loosen the vise and rotate the receiver until the mount holes line up using my tapered edge finder. I was pleasantly surprised at how all four holes were within .002” of each other!
You bring up another great point about mounting a scope and that is what do you go off of to determine when the gun is level when everything is round. Here I am making another assumption that the mounting holes are in the center of the bore. Quite the rabbit hole but I am having fun!

 

[Yooper]

Outstanding work sir!

Have you done any "blueprinting" work on the gun?

I only have one Remington 700 action, and was thinking about making it my "first try" at blueprinting.

Out of curiosity, what caliber is it?

I blueprinted the action and sleeved and jeweled the bolt. I replaced the barrel with a Krieger stainless and chambered it for 22-250. I also built a custom in the same caliber with a Defiance action and another Krieger barrel. Great for the varmints out west!

 

[Yooper]

Here are some misc pictures of blueprinting the action and working the bolt.

 

[ken erickson]

Not sure what that is about but I bought this used and then blue printed the action and installed a new barrel.
There is no issue with the receiver. The issues have been with the rails and rings/mounts. As to how I set this up in the mill I will try my best to explain: first I clamped the receiver in the vise and using an edge finder established the center of the receiver. Then locking the table on center I loosen the vise and rotate the receiver until the mount holes line up using my tapered edge finder. I was pleasantly surprised at how all four holes were within .002” of each other!
You bring up another great point about mounting a scope and that is what do you go off of to determine when the gun is level when everything is round. Here I am making another assumption that the mounting holes are in the center of the bore. Quite the rabbit hole but I am having fun!

Having a separate non-indexed recoil lug on the 700 and similar series Remington actions is IMHO a quirk that makes things a bit challenging when working on them. As far as mounting a scope on a completed factory assembled rifles we assume a lot when it comes to the recoil lug being on "straight' and that the barreled action is inlet into the stock square. When my shop would mount a scope we would visually mount the rifle "square" in a padded vise jaws, step back and peer through the scope and align the vertical cross hair with an imaginary vertical line thru the center of the buttplate or pad.

While this system is not perfect and not acceptable for the bench rest guys it does a reasonable job for most midwest hunting applications. Canting a rifle can be very detrimental to accuracy as you know.

If your dealing with a 700 barreled action and reasonably sure the recoil lug is positioned "square" with the bolt raceways you can set the flat of the lug on a surface that you know is level and go from there with your crosshairs . Some folks will use a plumb bob down range to get the vertical cross hair true others will use a level on the scope turret tops . All that assumes a lot when it comes everything being square and true to start with. And YES, it is a deep rabbit hole, LOL.

 

[Yooper]

It seems that scopes are very forgiving when shooting 200 yards or so. Some people I have talked to just guess the reticle line up by eyeballing it to the barrel. And it will work out to 200 or so. Its after that that I think what I'm doing might mean something. But now other factors start looming larger such as wind, bullet drop and bullet energy. So it will be hard to be conclusive but I will know I have taken much of the scope factor out of it.

 

[McMXi]

Going down one of my rabbit holes just to satisfy my curiosity. Just for the heck of it, I put my Rem 700 action with the scope rings installed on the mill and checked them for parallel and alignment. What I found out was shocking! Nothing with the rings was even close to be in line. The picatinny rail had a twist, the rings were out of alignment over .040" and not parallel with the bore.

Out of interest, what brand of rail and rings, and are they steel or aluminum?

The worst bolt action rifle I ever owned was a Savage Weather Warrior in 7mm-08 Rem. The barrel twist was a joke, but worse, the front and rear bridges had been ground so poorly that they weren't in the same plane, but rather in parallel planes angled down back to front.

You can see the "wave" in the Picatinny rail when screwed down to the receiver. It was a new rifle and Savage wanted me to pay shipping both ways for them to look at it, even after I sent them a bunch of photos. You can also see how far off the Seekin rings were in the horizontal plane, and even in the vertical plane. The last photo shows my wife holding a straight edge on the rear bridge directly over the scope base/ring mounting holes. The straight edge should also be in contact with the front bridge but it's way off.

No amount of lapping of the rings was going to fix it, so I ended up fixing the receiver myself and selling the rifle at a bit of a profit a few years later. It was my first and last Savage rifle.

 

[McMXi]

Curious to know what that grind spot in the back face of the receiver that I highlighted with white arrow is and what is the over all history of your receiver? Factory base holes and factory contours?


View attachment 157673

Yeah! WTH is that cut about and the vertical cut to the right of it. Even the primary extraction cam looks weird.

 

[Yooper]

The rail was made by Warne and the rings were Weaver. Rail and rings were aluminum.

 

[Yooper]

I want to make a second rail that is lower than the first. Come along for the ride.

After cut to length and squared up, I have to mill one end down to compensate for the difference in height and radius.

Then I indicate it in and proceed to cut the front radius that I had preset in the boring head.

Same thing with the rear radius. Different boring head with the preset for rear radius.

Note that I use the same side against the fixed side of the vise for consistency.

More to come this weekend.