For one does someone know the radius?

And two does it cross reference to a more common action say a Pre 64 Win M70. Trying to get dimensions for a sight base

I believe it's a the same as a Pre 64 magnum, with the .435 screw hole distance.

That's what I was hoping for.
Thanks

FYI a Pre 64 was only a Magnum length

Could you measure from the top of the receiver to the bolt body; take half the bolt diameter and add the distance to the bolt from the top of the rear bridge; should give you the radius.

Kobe While that would give me the correct dimension for the front bridge it will not work on the rear which is the dimension I'm looking for.

Think of it like a Remington that has a 2" radius on the rear bridge but is lower then the front bridge. If done how you suggest the rear bridge would need to be 1.65" high from bore center an 4" in diameter

And If i had the action in hand I would just use a dial indicator and measure the drop from center and calculate the chord height.

I don't have the action but I do have a Pre 64 M70 and that I can measure.

There is a formula in the Machinery's handbook that will allow you to measure the radius. You use chord length height and a constant. Look it up, if you can't find it I will.

Jim
Thats the issue. I have the formulas I've used them more then I care to count. What I don't have is a Dakota action to measure. I do have a Pre64 M70 and if they are in fact the same I'm good. I just need a confirmation that the Dakota rear bridge and the pre64 M70 are the same other then hole pattern.

Thanks for the help

quote:

Originally posted by kcstott:
FYI a Pre 64 was only a Magnum length

I think they were actually all standard length, and the magnums were opened up in the magazine area. Either way, there are 2 different rear base sizes for the pre 64, and the magnum is .435 like the Dakota, and the standard length base is the same as current standard Md 70.

Yes there was only one length action but three variations in magazine size to accommodate various cartridges.

I'm going to check the action I have on have and see what it is and then measure the rear radius.
Thanks again Guys

[QUOTE]Originally posted by kcstott:
Yes there was only one length action but three variations in magazine size to accommodate various cartridges.

Actually there were four, I think. Three normally and the other oddball

If you can wait 6 weeks I can throw a correct Leupold base in the mail if that will help.

I have a 76 action here, my measuring tools are limited to a set of dial calipers and a machinists square but if I can help by providing measurements let me know.

Having said that, while playing around with my Dakota, if I lay a set of Talley Model 70 bases (#1 and a #24), a straight edge sits flat across the tops. Likewise, a set of Talley Dakota bases (#29 and #DA) will go onto a pre-64 magnum and the straight edge also sits flat.

They are not exactly compatible because on the 76 the holes are moved forward to accomodate the bolt stop, where on the Model 70 the front hole is moved rearward to accomodate the bridge cutout or the charger guide on the Target rifles.

When making custom bases for the M-70, I start with a 1.375 radius... fine tune or lap to fit. This doesn't necesarily work on post 64's that I;ve run into..some seem to be "free handed"

Kobe thanks for the insight. good to know the details

Boxhead Thanks,I think I got it confirmed. I was planing on just buying a Talley base and measure it.

Free_miner Thanks. I think you proved it out.

Duane, Thanks again for sharing your tricks of the trade. I've seen a few Remington's Free handed that way. Looked like a kid with a belt sander got to it.

To everyone thanks for the effort I believe I have the information I need.

kcstott, I assume this is for your peep sight project.

If it would help I can send you a pencil rub sketch of the Dakota rear bridge so you can locate the mounting holes to position the base correctly fore/aft on the bridge.

Sure that would help.
Its actually for a set of scope bases that will have the Tom Burgess flip up sight.

I really appreciate it.