Holding zero
- Thread starter nwolf
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moombaskier
Well-Known Member
I had a loose base once and the groups fired looked like 2 separate good groups about 2" apart. I finally traced it down by dry firing and watching the cross hairs randomly shift back and forth. I grabbed the scope and could feel it move just a little. It drove me nuts for a while!
pressman
Well-Known Member
i am not a scope expert by no means but i am going to say no way. could this happen. i could see it move due to recoil but coming back to zero?
Now the cross hairs might flex maybe but you would never know it or see it at least that is my opinion. why would you ask this question? and what kind of scope are you using? not sure what your problem is that would let you think something like this is happening.
Now the cross hairs might flex maybe but you would never know it or see it at least that is my opinion. why would you ask this question? and what kind of scope are you using? not sure what your problem is that would let you think something like this is happening.
First off, nothing is loose, checked and rechecked. The problem is that cold bore shot is dead on. Second shot, if fired within 30 seconds of the first will be 2" low, third shot lower still. If I wait a couple minutes between shots it will shoot 3/8 groups.
Now before anybody says anything about the barrel getting hot, does your .223 get hot after one shot?
I know that the springs in the scope can cause problems, which is why when you make an adjustment on some scopes it takes a couple shots for it to settle. Or you tap the side of the scooe after adjustment. I just wonder if they can settle on there own after a few minutes.
Now before anybody says anything about the barrel getting hot, does your .223 get hot after one shot?
I know that the springs in the scope can cause problems, which is why when you make an adjustment on some scopes it takes a couple shots for it to settle. Or you tap the side of the scooe after adjustment. I just wonder if they can settle on there own after a few minutes.
pressman
Well-Known Member
Well a 223 is not a big recoil gun and you are right i have not had any gun heat up that bad after just one shot. has this pattern happened more then once? are you shooting from a bench with bags? is this a bolt gun or an ar platform?
Every time, at least for the one day I have shot it. The thing that made me think of this is that this scope has the adjustment problem I was talking about before. When I make an adjustment, it takes a few shots to settle it in. Since I already know the springs are sticky, how much of a stretch is it to think they may be doing this. I will be at the range thursday with a new scope in hand. I will make sure it is still stringing with my scope, then change it out. If it still strings, must be the rifle. If not, then looks like I've found a new problem we can have with a scope. Just what we need.
davewilson
Well-Known Member
do you have an AO parallax adjustment on your scope?
Make sure both the AO and eyepiece locks are reasonably tight. What kind of scope is this? Some cheap scopes have poor internals. Glued in prisms are a frequent problem. Try a different scope. If the scope is new, send it back.
I have seen this happen a few times over the years. It usually got down to one of a few issues.
Scope bases aren't tight. And you think the are. Check to make sure the base screws aren't bottoming out. It will seem like your tight but a small fraction is not always perceivable. This has been a issue with some Savages that have blind screw holes in the receiver. Had to file the screws down.
Bedding issue. I had a Model 70 that would shoot the first shot perfectly. The recoil would flex the action in the bedding after the shot. After a few minutes it would settle back to the original position. Re-bedding fixed it.
Scope problem. The recoil shifted something against tension in the scope that would reflex back a short time later. Very possible to have this happen. I have seen it even with light recoiling rifles. I have a scope right now that did exactly what you describe. A Leupold that had a custom Reticle put in it. It was OK before. Changed the scope
and the problem was gone.
Scope bases aren't tight. And you think the are. Check to make sure the base screws aren't bottoming out. It will seem like your tight but a small fraction is not always perceivable. This has been a issue with some Savages that have blind screw holes in the receiver. Had to file the screws down.
Bedding issue. I had a Model 70 that would shoot the first shot perfectly. The recoil would flex the action in the bedding after the shot. After a few minutes it would settle back to the original position. Re-bedding fixed it.
Scope problem. The recoil shifted something against tension in the scope that would reflex back a short time later. Very possible to have this happen. I have seen it even with light recoiling rifles. I have a scope right now that did exactly what you describe. A Leupold that had a custom Reticle put in it. It was OK before. Changed the scope
and the problem was gone.
Thanks for that. Its on an AR so cant do anything about the other items.
I didn't realize you were shooting an AR. One more thing for AR's. It doesn't sound like this is your problem but looseness between the upper and lower can cause random impact point shifts. I don't like using the tension pins that are available since they loosen and tend to wear out the pin holes in the alloy frame. I use the plastic wedges available from Brownells but make a modification. I drill a small hole in the base of he wedge. I then take a 1/8" diameter spring like a rebound spring for a smith and wesson revolver that is cut to length and pressed into the hole. This modification applies additional tension and the plastic doesn't compress over time. Works great! I'm an AR nut, and shoot 200-300 yard egg shoots with them about a dozen matches a year. When set up well an AR can give the bolts a run for the money.
Ok, I took the rifle out with a scope I know is good. I did ladder tests with two powders and four bullets. I cant get it to shoot better than 1 1/2" groups. It also throughs fliers several inches outside the group pretty often. I am going to try again with a different scope mount next week. Any other thoughts?
The chances of two scopes being bad is pretty low. Does your rifle have a picatinny flat top? Maybe it's not the scope/mount that is causing the problem. Have you had the rifle shooting well previously. What kind of AR, and what is the barrel/twist.What are your hand loads, bullet weight?
