Bert H. said

 For the Model 70, many people chose a Weaver scope.  

Maybe many did, but they were the cost-conscious ones; at the time of the 70s inception, the best US-made hunting scopes were Noskes & Lyman Alaskans.  (Excluding the very expensive German scopes.)  But for a 70 with blocks for a target-type scope, Fecker, Lyman, Unertl, & several smaller makers would have been among the options; no one particular make predominated.

Hi ptrossler-

I will assume that you are looking at a pre-war Model 70 (or Model 54) Super Grade 220 SWIFT that has a 26″ standard barrel contour.  If I’m wrong about the barrel please let me know.

The standard sight mounting provisions on the pre-war M70 consisted of a 3/8″ dovetail in the rear sight boss of the barrel, two 6-48 D&T holes on the top of receiver ring, and two 6-48 D&T holes on the left side of the receiver below the bridge (intended for mounting a receiver sight like the Lyman 48WJS).  No factory D&T holes were provided on the top of the bridge (for a top mounted scope base like the Redfield JR), the top of the barrel (for a Lyman or Unertl telescopic sight block), or left side of the receiver (for a G&H or similar side mount).  Any D&T holes in those locations were almost invariably non-factory.

To mount a target type telescope, e.g. the Lyman, Unertl, Fecker, Litschert, etc. the approach was to use a cross dovetail block (Lyman/Unertl BK works) in the barrel dovetail and another block (Lyman/Unertl U works) on top of the receiver ring.  It would look like this (on a M54):

Commonly used domestic top mounted telescopes of the pre-war era included (as Clarence says) the Lyman Alaskan, Noske, and Weaver G330.  Several manufacturers (notably Stith and B&L) made scope mounts that utilized the barrel dovetail and/or the holes on the receiver ring top and left side rear of receiver, permitting a scope to be mounted without adding D&T holes to the bridge.  A typical Stith installation of a Weaver G330 on a pre-war M70:

In the pre-war period, the factory catalogs did briefly offer to furnish and install the G&H side mount with Lyman Alaskan (by name), but soon changed to just a general statement that telescopic sights and mounts could be furnished (prices on request).  So…  It is POSSIBLE that a D&T hole in the bridge (typically just one hole spaced for the Redfield JR base) or a G&H side mount could have been factory supplied.  HOWEVER the vast majority of such applications were done outside the factory and it is generally impossible to document that extra D&T holes in barrel or receiver were factory work.  It is often possible to prove that such holes aren’t factory work, but the opposite is problematic. 

Therefore, from the collector’s perspective it is best to assume that any deviations from standard are aftermarket modifications, and the value of the gun should be adjusted accordingly.  Conversely, from the shooters perspective such modifications might be viewed as improvements.  I know my friend Clarence will agree with that…

Hope this helps…

Lou