Issue when sighting in the scope on my Mini-Thirty

[spacecoast]

On my last outing to the range I went to the big boy area for sighting in my scope, and came across a weird problem.

Having determined that the scope rings really has to be torqued down to avoid the recoil to loosen them, I made every attempt to do this right. After every 2 shots I checked to see if it was still firmly attached, and it did stay put the entire session.

When I sight my scope, I do so without the magazine, loading each round one at a time. This is a slow process and helps keep the gun cool and me not rushing.

I started out at 25 yards to make sure that zero didn't move off target (I remove my scope after each session), and it was fairly close. A few clicks up and a few to the right and I was on the bull. Next was the 100 yards and I was pleasantly surprised. It grouped around 3" and just a little high(?), so a few more clicks and I was centering them around the bull in those 3" groupings. Very happy indeed.
Waited for the range to go cold, about 10 minutes, and went downrange and pasted over my prior shots so I could assure myself that I was indeed a crack shot.

Next session I took careful aim and fired. 5" high! I tried again with same result. Then a few more and all were high! I was about to throw a fit, so I checked the scope and it was tight on the rifle.
Can anyone tell me what gives here? Why would they jump about 5" after a little rest? The barrel wasn't hot, just warm, so that wasn't the issue.
I took the scope off, inserted a full mag and started plinking fairly rapid at the 100 yards, and managed to get about half of the round on the target, one in the bull, so maybe I don't need that pesky scope after all?

I don't know which of the factors caused this (scope, rifle or shooter), but if anyone have an idea I'd greatly appreciate it.

In the meantime I am selling my almost new scope (Tasco Mil dot, 3-9x40) and adding a red/green dot instead. Looking at the leapers because they are in my price range, but am open to suggestions in the sub $75 range.

On a side note. Just ordered an ATI folding tactical stock with all the rails needed for just about any accessory imaginable.

 

[Bigboreshooter]

A couple of things come to mind:

1) Removing and re-attaching your scope will almost certainly cause some shift in point-of-impact at 100 yards. H&K's famous "claw mounts" on their high end rifles were supposed to "guarantee" that the POI didn't shift more than 1" each time the scope was removed and re-attached.

I like the Ruger scope mount setup a lot, but I wouldn't expect it to hold perfect zero when taking the scope on and off.

2) Hate to say it, but you really should look at getting better optics. You don't have to get a $1,000 German scope, but $75 Tasco's and Leaper's are not going to perform like good scopes do. Though the recoil is not heavy on your Mini-30, a semi-auto of that type gives the scope noticable jolt each time the rifle is fired. Better scopes will hold their zero better on such rifles. You can get a pretty good, and durable, scope for $200 or less from Nikon, Burris, and several other manufacturers.

 

[spacecoast]

Thank you Bigbore...!

I remove my scope when I am done shooting and not in between sessions while at the range.

I wondered why the groups went up about 5" after I had shot the first 10 rounds. As I said in the first post, the rifle got nowhere near "hot" since it was single shots with a manual reload after each shot.

It just made absolutely no sense to me that they would drift up.

When I get my new ATI stock I will leave the red/green dot permanently mounted. The reason I took the scope off was to facilitate cleaning the beast without worrying about damaging the scope.

 

[Kanook]

Get yourself a jar and start saving for a better scope.

You say that you can only put $75 to $100 woth of glass on it. Will it be the same in 6 months?

When I was able to work, I was alloted $5 a day for food and drink from the wife. I would make a gallon of tea the night before and when that was gone, I would fill up with free water from the job site cooler. Eat Bfast at home, grab a hot dog for lunch and that would leave me about $3.50 left over everyday.

Throw that money in a jar and forget about it. After a year of saving, you will have $875, or enough to get the wife a present that she will not know how you got the money. Or it'll pay for the 2 week off for hunting trip, or in 3 months of saving you can get a pretty good scope.

Now that I can't work it's hard to save, but it is not impossible, and the wife still can't figure out how we can do it.

 

[spacecoast]

You just might have an idea, but keeping in mind why I bought the rifle in the first place, the $75 limit may just be where I am at, and the range limit of 100 yards I just can't see spending several 100's just for the fun of it.

I am not a hunter, never will be, but I enjoy plinking at the range since it is only about 5 minutes from my home (I live inside city limits). I have a .22 (Marlin Papoose) which I enjoy shooting, and so does the wife and grand kids. The Mini-30 was just for me for the above reason, and next reason was for eradicating zombies. Lastly it is a last resort for putting meat on the table.
For home defense I have plenty of more suitable weapons. and the Mini-30 was plenty expensive for something that hopefully will never be more than a toy for me.

That said, I am looking at the Leapers UTG, 1x32mm red/green dot at Cheaper Than Dirt for about $50. Anyone have any experience with these? The get pretty good feedback from customers, something than can't be said about a bunch of the sub $75 optics.

BTW. the Tasco 3-9x40 I got retails at $130, and yes I got it cheaper than that, but I still expected $130 worth of quality. That is if it is the scope and not the rifle that has a problem.

 

[Jimbo357mag]

I think 10 rounds is more than enough to heat the barrel and move POI 5" at 100 yards. Older Mini's were known for shifting POI. More trips to the range will confirm that. 8) 8)

...Jimbo

 

[spacecoast]

It is true that the barrel heats up pretty quick, but at no point was it too warm to wrap my hand around it, so I'd say that heat wasn't an issue here...

I ordered the red dot today, so I should be able to tell if it is the rifle, the scope or the shooter who is the problem.

I will give the scope another go if I don't sell it locally, and hope it was just a bad day at the range.

Thanks for the inputs and suggestions!