Not what you would expect...

[Antelope_Sniper]

Recently I was having a bit of a problem with one of my rifles...it wouldn't shoot very well, and realized on of my bases wasnt' tight. I knew one of the holes had been slightly stripped (because I did it ). So I pulled the scope off, leaving the rings on the scope, took the bases off, dropped them in acetone overnight to clean off the old lock-tite (hmmmm someone here game me that idea ) Took it to the smith at BassPro, and had him re-tap the hole for me.

The BassPro Smith was real nice, and did it for FREE. 8)

So I put everything back together, with lots of blue lock-tite, took it out and shot it...and the point of impact only moved an inche at 100 yards. This fixed my accuracy problem, the gun new shoots sub 1/2"

Back at the house, I noticed my crosshairs were a little crooked....the scope was tilted a few degree's to the right, so loosened the ring screws, careful not to change anything other then straighted it up.....took it out and shoot it.....

This moved the point of impact 9 inches to the right and two inches down. :?

Completely take everything off, impact doesn't move....straighten it just a little bit....off the paper....

 

[Kodiak]

Just taking a guess here. Through the years of messin' with scopes (about 60 years) I have found a problem or two as you describe. The scope x-hairs are not stable within the scope body and no. 2, the scope rings are not in perfect alingment when you tighten them around the scope body. Of course, there may be other problems poppin' up here also.

Best of luck,

Jim

 

[JD338]

Antelope_Sniper

What make and model scope do you have?

JD338

 

[Antelope_Sniper]

Leupold VXIII 6.5-20. 30MM tube, sidefocus, Mil-dot.
Standard Leupold 2 piece bases, dovetail front, and Leupold Rings.

I wouldn't exactly call this a problem. I moved my zero to the center of the paper, and proceeded to shoot two groups under 1/2".

When I took everything off, and put everything back on, that's when I expected to miss the paper. Of course I was very careful during the process, and was suprised to see my zero stay virtually the same.

I thought it was interesting that what I thought was the smaller change, created the larger change in zero.

I hope to never have to change these rings again...but on my future mounting jobs, I might take Kodiak Jim's advice and use a torque wrench. That way if I have to remount, there is one less variable to worry about.

 

[onesonek]

Well, whether it be the case or not here's a couple thoughts.
First, it seems seldom that the reticles is is truely square in relationship to horizontal and vertical planes. Undoubtedly you had originally sighted in the scope, and made both vertical and horizontal adjustments from the factory optical center. So, when you remounted it, it is likely you were very close to your oringinal mount. Then when deciding it was "off kilter" a tad, and change it, it may and likely was different from the first mounting. Changing/rotating the scope will change the reticle's poi because the erector tube in which the reticle is mounted changed from it's original sight in position by a fair degree. If you made the poi changes you want and it shoots fine, it's no big deal, the reticle is fine I would think. It all goes back to your original sight in and how much adjustment was made at that time, taking the erector tube away from optical zero.
This is why some/most long range shooters have levels mounted. Any slight canting changes.

Just a thought or 2,

Dave

 

[FOTIS]

There was a redfield JR mount ad in the gun rags back in the 70's-80's.
It read

".003" movement of the scope in the ring means 12" at 400 (I think) yards"


yes it can and will happen.

 

[BillPa]

I'm pretty anal when is comes to mounting a scope. The last thing I'm going to do is just slap things on, apply a half gallon of Loctite and call it good.

The reality, someone made a receiver,someone made the bases-rings and another made a scope. Any bets they actually match?

One tool that everyone should own if they mount scopes....
http://www.kokopelliproducts.com/scopeb.html

...and NO, I don't work for or sell them. Just a good product.

They will tell you how things are aligned in a few minutes without measuring. Its not a "new" idea, I have a set made by my late uncle in the 70s and I've made a few sets over the years. Unlike the "pointy" bars tell you next to nothing other than the point meet, they show you any mis-alignment at a glance.

The fun part....once you've determined the rings are as straight as a dog's hind leg then you can start the search why. Bent-twisted receivers (common), action dimension differences(common), base(s) that fit the receiver(uncommon), rings that really match the scope tube diameter (uncommon) and finally, is the scope tube actually straight! Even simple things are overlooked, are the screws really the right length or do they bottom out in the blind hole, the barrel threads or only engage a few of the threads?

We carefully bed our actions for as close as possible a unstressed 100% fit in the stock . Why not the bases and rings to the receiver and the scope to the rings for exactly the same purpose? I've bedded rifles when the action screws were tightened it locked the bolt. Why would anyone want to mount a couple hundred dollar scope then bend the snot of it?

I've made the statement that 50% or more scope problems are due to improper mounting, maybe more. I've remounted scopes when the top half of the ring was removed the scope sprang up and cleared the lower half a 1/16" or more.

I know guys say "I used this out that", "I only buy" or "are the best" and "never had a problem", but even the best of stuff isn't the best of stuff if it doesn't fit.

Bill

 

[Guest]

Scope mounting is one of those areas that most people overlook or believe good enough is good enough.

As for the measurements, you can count on things approximating .001" equalling 1moa, but that's just an approximation. Burris Signature rings operate on the same principle, and I've verified it. I had a rifle with misaligned bases and a scope with 25moa of adjustment up from center. I was still about 3" below the bull at 100yds at the end of adjustment of the scope, and I added back .030" using the Burris offset inserts and got things right in line.