How is any sporterized rifle with a 2 piece scope base accurate?

[pavementends]

I want to set up one of the family heirloom rifles as a proper, ready to go hunting rifle that will be accurate and reliable. If there is a lot of misaligned tension in the scope mount, I'll worry the scope base screws will break again.

Some fine people have suggested various ambitious courses of action involving lathes and jigs. Others have proposed that I ignore the misalignent and just screw the pieces together.

How about this for a middle of the road fudd home gunsmith solution:

First a separate, straight, piece of picatinny rail to mount decent rings to a seemingly straight scope. I then decide which of my loose scope bases appears to be taller than the other (with respect to the top surface on which the scope mount stands). Could possibly create a difference in height with a thin shimming operation, but holding the rifle to flat surfaces make it seem as if the front base is true and the rear is unaligned and lower than the front.

The base which appears taller and truer is left screwed in place while I put a smudge of some bedding compount beneath the other. I then use the scope with the prepared scope rings to force the floating base in alignment with the screwed fixed base.

I want to set up one of the family heirloom rifles as a proper, ready to go hunting rifle that will be accurate and reliable. If there is a lot of misaligned tension in the scope mount, I'll worry the scope base screws will break again.

Some fine people have suggested various ambitious courses of action involving lathes and jigs. Others have proposed that I ignore the misalignent and just screw the pieces together.

How about this for a middle of the road fudd home gunsmith solution:

First a separate, straight, piece of picatinny rail to mount decent rings to a seemingly straight scope. I then decide which of my loose scope bases appears to be taller than the other (with respect to the top surface on which the scope mount stands). Could possibly create a difference in height with a thin shimming operation, but holding the rifle to flat surfaces make it seem as if the front base is true and the rear is unaligned and lower than the front.

The base which appears taller and truer is left screwed in place while I put a smudge of some bedding compount beneath the other. I then use the scope with the prepared scope rings to force the floating base in alignment with the screwed fixed base.

Once you have decided to us a pic rail you are half way there. Most rails are quite "true" you should be able to mount the rail shimming which ever end needs it, and use epoxy to insure there is no stress on the rail. Then with the use of Burris rings with the inserts you should be able to align the scope also without stress. Nothing should bend when you tighten things up and the Burris rings are great.

 

[Lenny Foffa]

!. The Wheler Scope Alignment kit would be useful to you. It comes with TWO alignment bars, 1 inch and 30mm
2. Yeras ago the Gunsmithing team of Miller and Crumm ( Spelling ) used to weld bases to actions and blend the weld so no seam or weld line was ever visible. If you going to own and shoot a rifle your entire life, it ,may be worth the expense. I like Leupold STEEL, Dual Dove Tail Bases, simple and strong. If I owned a rifle that was difficult to mount bases too, I would seek out a gunsmith, who knew how to properly weld ( Not a welder who thinks he is a gunsmith) ,those two Dual Dove Tail Bases to the receiver. The issue is then gone forever. Just my humble opinion. Good Luck Buddy

 

[ntsqd]

It cost me an insane (for a set of screws) amount of money to get the spare screws that I have. I love to measure my bullets in inches and my powder in grains, but you guys are really missing out when it comes to screws. If I ever have to re-tap those holes it's going to be in M4. But the advice is taken, that a larger diameter screw might be a solution.

I am intrigued by the method described in this thread, however:

Bedding Two-piece Scope Bases

www.rimfirecentral.com

That is essentially what I did with the one piece base that screwed down tilted due to shape of the receiver. I suggest the linear bearing shafting as a lower cost solution than the mediocre Wheeler alignment kit. That you're in Sweden does complicate things, no idea who to suggest as a vendor for the shaft and I suspect importing it from McMaster isn't as cost effective as a local source should be.

Unless the welder/gunsmith is also a heat-treater who knows what he's doing with an H-T oven there's no way that I'd ever consider welding to a receiver!

 

[cabelasken]

My gunsmith laps the rings and then put a small dab of permatex on the rings before putting the scope in place and aligning it. He also uses blue lock tite on the mounting screws. I missed three bucks in succession about 25 years ago and took the 284 win a-bolt to him to replace the barrel as it had over 6000 rounds down the factory barrel. He replaced the barrel and when I picked up the gun he asked me if I knew the scope mounts were loose.

 

[Dentite]

I have plenty of experience milling and setting up bases on Mauser '98 actions. Why you use a 2 base set-up is for the sole reason to have WINDAGE adjustment on the rear base and ring. You can also use a single one piece base, but again the rear ring has WINDAGE adjustment.
Most base screw holes are machined using a jig, even at the factory, and others are CNC milled, mistakes happen on production items.

You are overthinking this, even today, actions are milled off centre for scope base holes. My own Win Model 70 EW 338WM is out, it was a warranty job, milled it true from 6-32 to 8-40 and fixed it, then the customer decided he didn't want to buy more bases, which wasn't actually necessary, and sold it to me half price. It was brand new…

Cheers.

I got into hunting and shooting later in life. So while I have misurps that are over a 125 years old, my oldest hunting rifle is less than 10 years old. I've got some with a one piece pic rail and rings clamped onto that, but most are Talley Lightweight one piece mounts. ARs I always use one-piece mounts.

I never understood the point of a rear scope mount with windage adjustment. Or even the dovetail type you turn in. Why introduce a second interface?

If you are using the rear windage feature on a windage adjustable scope mount, you are torquing the scope, correct?

Or are you saying you can use the windage adjustable mount to correct drilling errors on a old sporterized milsurp that wasn't done correctly?

Thanks.

 

[ntsqd]

The story I was told was that old scopes didn't have the range of adjustment needed to deal with slightly misdrilled mounting holes.

I was taught to mount scopes by centering their windage adjustment, and then setting the windage against the collminator by turning those windage screws in the rear base.

 

[MagnumManiac]

Or are you saying you can use the windage adjustable mount to correct drilling errors on an old sporterized milsurp that wasn't done correctly?

With this style set-up, you mount the bases, then you use a steel 1", or whatever diameter required, MACHINE TURNED bar to align the rings. Then you mount the scope. Been doing it this way for 30 years.
If mounting a rail, and the mount holes are out, what do you do then?

Just to add to this, when I was building LR/ELR rifles, EVERYTHING was re-cut/drilled/tapped to centreline and pinned front and rear. I used a lot of CZ 550 Safari Magnums, they have integral dovetail mounts for scopes, did I use them? No, I machined/ground them off and used rails pinned and bedded to the action…

Cheers.

 

[Dentite]

With this style set-up, you mount the bases, then you use a steel 1", or whatever diameter required, MACHINE TURNED bar to align the rings. Then you mount the scope. Been doing it this way for 30 years.
If mounting a rail, and the mount holes are out, what do you do then?

Cheers.

This is the type I've seen advertised, a dovetail front base where the ring is then "turned" into position to engage the dovetail with a lapping bar, etc. Then the rear ring sits on that base trapped between the windage screws on the base.

So if you crank the front ring into the base until it stops, and then you use the windage screws at the rear, how are you not torquing/tweaking the the scope? Or at the least, if the front and rear rings aren't aligned, you aren't going to get good ring-scope contact unless the scope is tweaked.

Or are you saying both the front and rear are windage adjustable mounts in the type you use?

 

[MagnumManiac]

Explain how you gather the hype that the scope is being torqued?
Explain how a rail is a better at mounting a scope.
I really do not understand your thinking here, the front ring turns in the base, if it didn't the scope would be banana'd from the twisting. How come, you can pick up a 12-14lb rifle by the scope and have zero affect on the tube?

Cheers.

 

[Dentite]

Explain how you gather the hype that the scope is being torqued?
Explain how a rail is a better at mounting a scope.
I really do not understand your thinking here, the front ring turns in the base, if it didn't the scope would be banana'd from the twisting. How come, you can pick up a 12-14lb rifle by the scope and have zero affect on the tube?

Cheers.

Sorry I'm not making myself clear. Would be easier if we in person I could use my hands to describe what I'm asking.

Okay, are you saying that when you crank on the rear windage screws, the front ring also turns in the dovetail base? In other words, the front scope ring freely turns right and left to maintain alignment with the rear scope ring as the windage screws are turned moving the rear ring?

If that's what you are saying, that makes sense to me. But I had assumed that installing (rotating) the front ring into the front base took some pretty good force (hence using a lapping bar and not the actual scope). Can this force be overcome by the force of the rear windage screws? I assumed the front ring was so tight in the front base that it wouldn't freely move, but the scope body itself would be torqued/bent as the windage screws are turned.

Hopefully that makes sense.

 

[MagnumManiac]

Sorry I'm not making myself clear. Would be easier if we in person I could use my hands to describe what I'm asking.

Okay, are you saying that when you crank on the rear windage screws, the front ring also turns in the dovetail base? In other words, the front scope ring freely turns right and left to maintain alignment with the rear scope ring as the windage screws are turned moving the rear ring?

If that's what you are saying, that makes sense to me. But I had assumed that installing (rotating) the front ring into the front base took some pretty good force (hence using a lapping bar and not the actual scope). Can this force be overcome by the force of the rear windage screws? I assumed the front ring was so tight in the front base that it wouldn't freely move, but the scope body itself would be torqued/bent as the windage screws are turned.

Hopefully that makes sense.

Yes, the front ring freely turns, there is resistance, but not enough to flex the scope tube. I actually put grease on the ring dovetail, and so should everyone…

The truth is, any misalignment should be corrected by milling the screw holes larger on the centreline, regardless of the type of bases/mount being used.
My Win Model 70 EW in 338WM is a prime example, front base holes were .025" off centre and crooked to the centreline of the action, 8-40 holes just cleaned it up, the rear holes were correct, but all were altered. The 8-40 screws are stronger on 338's and larger magnums anyway.

Cheers.

 

[Dentite]

Yes, the front ring freely turns, there is resistance, but not enough to flex the scope tube. I actually put grease on the ring dovetail, and so should everyone…

The truth is, any misalignment should be corrected by milling the screw holes larger on the centreline, regardless of the type of bases/mount being used.
My Win Model 70 EW in 338WM is a prime example, front base holes were .025" off centre and crooked to the centreline of the action, 8-40 holes just cleaned it up, the rear holes were correct, but all were altered. The 8-40 screws are stronger on 338's and larger magnums anyway.

Cheers.

Okay that makes sense, thanks.

 

[6fatrat]

Bed your bases, lap your rings.
Not rocket science

 

[Hugnot]

I did a hasty amateur job - not receiving compensation (no pay)

Centered scope reticle using a mirror,

Shimmed up low base using aluminum pop can pieces so bases were level.

Put scope(s) in Burris Sig rings & swivel plastic inserts to allow elevation & windage bore sight zero.

Used Hornady 4DOF or other ballistic calculator to determine if I had a comfortable amount of elevation with intended load to hit at longest range with remaining elevation.

If not enough elevation add 1-3 aluminum pop can layers (.008 - .011) to jack up rear base.

Glue down entire works with blue lock tight. Use T15 base screws at 15-25 inch pounds on steel receiver, depending if (6-48 or 8-40) to squash aluminum down. Wait 2-3 days for blue lock tite to cure.

No problems for many years (over 10). Works just fine on olde Mauser rifles having uneven base mounting surfaces. Blue lock thread locker prevents electrolysis between aluminum & steel.

Don't try this with non Burris Sig rings.