Does this sound like a bad scope?

[Fusion]

I apologize in advance for the long post.
I got out to shoot my muzzle loader some today before our season starts and I'm wondering if I now have a scope that's given up the ghost. Let me start off by saying it's a cheap $30 Tasco Bucksight from Walmart and I'd not buy a cheap scope like that now, but at the time I didn't know better, and I've had it for 5 years or so and it's never given me a reason to doubt it or change it. It's also got a lot of memories to go along with it mounted atop my muzzle loader, so I really am hesitant to just change it. Everything else I hunt with has much more expensive optics now.

Anyway, this past season I removed the scope from the gun and then reinstalled it. When I went to zero it, I didn't have the greatest bench to shoot off of, but it was good enough. I shot 5 shots, and 2 of them were about 2" right, and 3 of them in the bullseye. I figured I must have pulled the 2 that went to the right, and that it was close enough. I went hunting, and the bullet impacted exactly where I wanted it to with the deer I shot. I thought all ways fine. At the end of the season I took the gun apart and cleaned it well, including taking it out of the stock, etc. The gun had also ridden in the truck some during the season and while I didn't drop it, I'm sure it did feel some bumps in there.

Fast forward a month or two and I got it out just to shoot. When I shot it, all of the shots impacted to the right about 2". I thought this seemed odd, but then I thought maybe that I just didn't have it sighted in well and the 3 in the bullseye had been what I'd pulled, or maybe where I'd taken it out of the stock, it just was too many variables to rule it as a scope failure. I didn't end up getting out to sight it back in until July. So in July I got out and shot it to sight it in.

This is what I got. The two to the right were the first two, then I moved it too far left, and then I moved it again and shot those 3 dead center. I was happy with it, and even tried banging the scope around some by banging on it, etc. It held up all day and shot where I wanted.

I took it home, cleaned it without taking it out of the stock, and put it away.

So fast forward to 2.5 months later and I get it out today to go shoot it. I go to the range instead of shooting on our property, so once again I don't have the best rest, but it works well enough to get by. So I take the first shot shooting at the small target in the corner. I miss the paper completely, but then I shot a couple more. What I now notice is once again it's shoot 2" to the right.
Ignore all the other bullet holes, but you can see the two to the right. One is right over 1" right, and one about 2". Also ignore the group size as it's due to me not having a great rest.

The only factors that changed were I was shooting slightly downhill when I zeroed it, and now at this range you have to shoot uphill. Could that effect it shooting to the right? I know my other guns shot about 1" low here from when they were sighted in on our property where we shoot downhill, but the other one wasn't off windage wise.

Anyway, I made some adjustments and got it centered again, and it will shoot dead center all day long. It shots a tight group like normal, it shoots the same spot if you bang on it somewhat, and it just seems to work exactly like it should when at the range. I'm just wondering where it's going to shoot 2 months from now.

Has anyone else had anything like this happen? Does it sound like a bad scope? The scopes I've had go bad in the past have always shot all over the place. It just seems really odd to me that it would shoot great all day and not move from recoil, getting bumped, or anything like that, but that it would lose zero in the house. Should I suspect this scope, or could it have been shooting uphill, or some other factor? Have any of you all had a scope do go bad and do this, or do they normally just start shooting all over the place and moving with each shot?

Like I said, I've just got a lot of great memories with this combo and I hate to change it, when something may not even be bad. Otherwise if it wasn't a situation like this I'd change the scope for piece of mind.

 

[rickyrick]

What distance, could be parallax. Also it could be weather changes affecting the stock contact with the barrel.

I know very little about muzzleoaders, but since you said that you took it out of the stock that's my guess.

 

[Fusion]

It was 100 yards. The first time It was doing this I'd taken it out of the stock, but after I saw that I adjusted it so it was shooting in the center, and I made sure to clean it this time without removing the stock. I then put it up to store for 2.5 months and when I took it out it did this. I should have clarified that. Sorry.

It was a temperature change. I'm not sure what the temperature was while I was shooting it yesterday, or the time before, but it was probably 65 or 70 degrees max or so yesterday, and I'd guess in July when I last shot it more than likely it was more like 85-95 as it rarely gets below that. So it was cooler could that make that much of a difference?

 

[HKFan9]

Could be the weather.. or you mentioned you had a bad rest... could be that even. Rifles shoot much better when you use their natural resting state.... rather than putting force and stress on it to hold it on target.

 

[Fusion]

I ended up getting the sand bags positioned decently, so I got a decent rest and start shooting good groups. Like I said though, I'd had to adjust it to the get those groups centered. So it definitely was shooting to the right, but the weather may have been the case. I just am unsure of how much the weather will affect it. I guess I need to try to go shoot it again and see how it does this time after sitting for a couple of days.

 

[HKFan9]

Is it a wood stock? they can swell up depending on weather conditions and change POI

 

[Fusion]

Unfortunately it's a synthetic stock. I wish it was wood, as they look so much better imo.

 

[Mobuck]

No way I can tell exactly what your problem is but I'll offer this info. Even the slightest crosswind will move a ML bullet a couple of inches @ 100yards. I found this true last year as I was prepping for a ML hunt in Colorado. I was having trouble getting the windage right on my peep sight from one day to the next until I realized there was slight breeze. When I got to CO, I shot my rifle at a public range near Salida on a dead calm morning(rare in that area). It was right on but when my partner showed up and we went back to shoot his rifle there was just a little wind right to left. My rifle was 2" left of center again. With the large profile and low velocity of a ML projo, even a breath of wind will do a number on your windage.

 

[ndking1126]

I'm going to guess wind too.

If not, Its probably a scope that doesn't hold zero well.. not necessarily broken, just not engineered well enough to hold a zero.

Anytime I've had a scope broken, it either won't adjust POI reliably (ex: 4 clicks to the left results in 3" instead of 1" adjustment) or each shot gets farther and farther off for no reason to the point where you can't even hit a 8.5x11" piece of paper at 100 yards.

 

[was123]

Save yourself some headaches and never make a scope adjustment after only one or two shots. Cheap scopes are famous for not tracking properly. Make a scope adjustment, shoot a 5 shot group, see what you have. It is not uncommon for the point of impact to wonder slightly for the first couple of shots after an adjustment. Secondly, and please excuse my ignorance regarding muzzle loaders. Are your first shots from an oily bore? Rifles tend to require a couple of foulers after cleaning before accuracy settles down.

 

[tim s]

Do you use any kind of windflag? This could quite easily be the change from a right to left prevailing wind.

 

[MZ5]

Any chance the rings are over-tightened? Any chance the POI shifts quite a bit during the first couple/few fouling shots (I know little about MLs, though I have hunted with one before)?