Verifying an old scope is still able to hold a zero

[Roamin_Wade]

Is there any way to somehow test a scope off of a rifle to assure it will hold a zero? I bought an old JC Penny Glenfield (Marlin) 30-30 that has an old Redfield 4x32 scope on it. I’ve taken the rifle all the way down and cleaned every crook and cranny on it, including scope, and then took it to the range recently. I ended up getting it in the circle every shot but it was all over the place. Is there any way I can “stress” that scope non-destructively, to see if it is good or bad to justify replacing it or not? Thanks in advance...

 

[LoonWulf]

Is there any way to somehow test a scope off of a rifle to assure it will hold a zero? I bought an old JC Penny Glenfield (Marlin) 30-30 that has an old Redfield 4x32 scope on it. I’ve taken the rifle all the way down and cleaned every crook and cranny on it, including scope, and then took it to the range recently. I ended up getting it in the circle every shot but it was all over the place. Is there any way I can “stress” that scope non-destructively, to see if it is good or bad to justify replacing it or not? Thanks in advance...

Id put it on another rifle that is a known value. Likewise you could put another scope on the 30-30 thats a known value. Test and see where the divergence is.

 

[Roamin_Wade]

Id put it on another rifle that is a known variable, likewise you could put another scope on the 30-30 thats a known value to test and see where the divergence is.

Great advice. Simple and result oriented. I was thinking there may be someway to set it in some v-blocks and aim at a target, put it through some shock loads like a rifle would do to it, and then set it back in v-blocks to see if it stayed.

 

[LoonWulf]

Great advice. Simple and result oriented. I was thinking there may be someway to set it in some v-blocks and aim at a target, put it through some shock loads like a rifle would do to it, and then set it back in v-blocks to see if it stayed.

If you had good machined V blocks you probably COULD do that. Youd have to make sure you put the scope down exactly the same and level each time.

 

[Bill M.]

You could use a laser bore sighter before and after “stressing” it. I also doubt if there is anything wrong with a fixed power Redfield scope of that era. The mounts, maybe.

 

[243winxb]

Staff tested the precision and repeatability of the adjustment dials by zeroing the scope, then locking it in a shooting vise and viewing crosshair movement over a 1" grid target. It was confirmed that each click equaled 1/4" of movement at 100 yds. Turning the dial 75 clicks in each direction and then 75 back confirmed that the crosshair returned to its original location.

https://www.americanrifleman.org/articles/2018/12/28/tested-hi-lux-xtc1-4x34-riflescope/

Zero means scope adjustment are in the middle. Do not turn the adjustment till they hit the stop. To hard and you break it.

An accurate rifle can be tested by shooting. 1.Fire a group for zero. 2. Adjust up 20 clicks & right 20 click . Shoot. 3. Return to orginal scope setting, fire a group. First & 3th group, should be the same zero.
I just did this a month ago. After gun fell off bags on to bench.

 

[jmr40]

I wouldn't trust the rubber seals on even a high end scope to still be in good shape after 30 years. And a modern $200 scope is a better optic than one that cost $500 30 years ago.

Some high end optics makers will refurb scopes with new seals. On the rest it is usually time to buy a newer scope.

 

[jmorris]

I have a 45-70 that I use to confirm one can hold up. It’s cheaper to shoot and actually has more felt recoil than my 50 BMG, with “Marlin” loads. If they live, I trust them.

Before I even put them on any rifle, I mount them in a vise and “box” them running up, right, down and left, the same number a few times, if they are not at the starting point, each time, no reason to even start wasting components.

The only time I ever put one in V blocks is to find its center adjustments, the aim point will remain in the center, if centered, if not, it runs in a circle, as the scope is rotated in the blocks.

 

[illinoisburt]

You could use a laser bore sighter before and after “stressing” it. I also doubt if there is anything wrong with a fixed power Redfield scope of that era. The mounts, maybe.

That's not a bad idea if you are referring to a cartridge type laser in the chamber with bolt closed. Look through the scope at small object a hundred yards away to verify where the laser is pinpointing. Give the gun and scope good solid raps with a rubber mallet then mortar the butt a few times on the ground. Look back through the scope at the same target. If the laser is pointing exactly as before then things are good. If it's pointing anywhere else, ya got a problem. Don't open the bolt or move the laser itself in the process.