Scope out of vertical adjustment

chiefjason

chiefjason

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Gonna pic the brain trust here before I start changing things. Gun is a CZ 455, used to be LUX, now sporting an American synthetic stock. So the stock was swapped recently. Took it to the range. Before I could make ragged holes in the bull at 25 yards without much trouble. Saturday it was WAY low. Ran the vertical adjustment all the way up. Last shot was on the edge of a 4" sticker target right at 6:00. That's where I ran out of adjustment.

I leveled the scope when I put it on originally and it shot very well in the wood stock.

So, it could possibly be a torque issue on the screws from the swap. Have not messed with that. But I only tightened the screws with a screwdriver, not sure I'm that strong.

I am also running pretty low scope rings. With the LUX and the drop in the stock I had too. And even then cheek welds were poor at best. So thinking I may need to get some higher rings.

Anything I'm missing or need to check?
 
Are the rings identical, maybe did you swap the rings front<>back?
 
Bailey Boat said:
Action screw torque, adjust both to 40 inch pounds and try again.
Click to expand...

No. In my experience most CZ's (and other rimfires) that are not pillar bedded prefer 21-24 in/lbs.

Jason we need some additional info: rings, base, & scope. Have you you checked the barrel channel for clearance (if you are desiring a free float barrel) ? I know my 455 is bedded the entire length of the barrel channel.

I have also used some flat gasket on my rimfires just in front of the action (Anz, Win 52, and CZ452) with good success.

I've also havd good success using DIP scope rails. I typically get the 25 MOA extended rail.

http://www.diproductsinc.com/Detail.aspx?PROD=175301&CAT=4268

Your POI shift could be several different things, but comb height and how the action sits in the new stock are the most likely culprits.
 
Catfish said:
Are the rings identical, maybe did you swap the rings front<>back?
Click to expand...

Scope was not removed in the switch. 2 bolts out, stock off, new stock on, 2 bolts in. It was sighted in well in the wood stock. No problems at all.

Scope is a Nikon 3x9x40, unsure of model. Rings have been on that scope so long I don't know. Just generic rimfire scope mounts, nothing special. They work great under the right circumstances. No base, dovetail on receiver.

The receiver and barrel just dropped in with no pressure. Could be touching but was not forced down at any point, unless tightening the bolts put pressure somewhere.

Heading to the LGS and my buddy is going to take a look at it too.
 
OK, Got a few more places to start. Rear sight ramp and scope bell are touching. Didn't seem to be an issue, but I'm going to tap the sight completely off. I just unscrewed the sliding rear sight and left the base to get enough space to mount the scope. Kept it quick and dirty. lol

Also, the barrel is only partially floating right now. A dollar bill hangs up right about where the rear sight is. So going to remove the stock and look at sanding it to get a bit more clearance. Even where it is floating it's kind of snug.

I may also swap rings front to back when it goes back together and see what that does.

JBoyette said:
What ever the forward rest is, that is causing the stock to touch the barrel.
Click to expand...

We were shooting it off of a sandbag. As tight as that clearance is in the stock, could be it. Plus it's actually touching something under the rear sight. Going to try and pull the stock back off tomorrow.
 
Bunsen said:
Jason, I'd open up the barrel channel as needed wherever you see a rub mark or the dollar bill hangs up.

As I mentioned earlier I've had good experience and observed no side effects to placing a 1.5" wide piece of flat gasket directly at the barrel-action junction on my CZ's. This "soft bedding" was a standard feature on the Win52 B's. ;)

http://www.homedepot.com/p/PartsmasterPro-6-in-x-6-in-x-1-16-in-Thick-Rubber-Sheet-58353B/206853053
Click to expand...

How much clearance before you put that on there? Standard dollar bill thickness or a bit more? does it affect the optimum torque on the action screws?
 
JimP42 said:
How much clearance before you put that on there? Standard dollar bill thickness or a bit more? does it affect the optimum torque on the action screws?
Click to expand...

Light sanding at most. The gasket I use is only 1/16" and it will compress some. There is typically a step down transition going from receiver to barrel and the gasket sort of fills that void as well as the one in the stock inletting. It sort of locks the action into the stock and acts as a slight dampener as well as barrel support.

Sorry I don't have any pics and I am not going to pull an action out of a stock just for pics.

I've never had any torque issues with the action screws and the gasket in place. 21-24 in'lbs on any rimfire that is not pillar bedded.

455's do tend to prefer a little bit of upward pressure on the barrel. That was the reason I was given when I got my djdilliondon Tacticool skimmed and bedded stock from him. He does do custom CZ work if you are looking for somebody.

My gunsmith typically skim coats the 4" closest to the action under the barrel then free floats the rest on all my centerfires. It's an older technique, not without it's merits.
 
Bunsen said:
Jason, I'd open up the barrel channel as needed wherever you see a rub mark or the dollar bill hangs up.

As I mentioned earlier I've had good experience and observed no side effects to placing a 1.5" wide piece of flat gasket directly at the barrel-action junction on my CZ's. This "soft bedding" was a standard feature on the Win52 B's. ;)

http://www.homedepot.com/p/PartsmasterPro-6-in-x-6-in-x-1-16-in-Thick-Rubber-Sheet-58353B/206853053
Click to expand...

So the rubber basically acts like a shim to lift the barrel slightly? I'll look into that.


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chiefjason said:
So the rubber basically acts like a shim to lift the barrel slightly? I'll look into that.
Click to expand...

To a minimal degree yes. Based on the info you have provided I am hypothesizing a somewhat sloppy fitment of the barreled action in the stock. The soft bedding technique is an easy an inexpensive way to test that without going to full pillar bedding right out of the gate.
 
Before doing anything else I'd swap back into the old stock and see how it shoots. Hate to test a bunch of stuff when you may have bumper/broken the scope somehow in the process. Probably not, but worth checking.
 
Bunsen said:
Light sanding at most. The gasket I use is only 1/16" and it will compress some. There is typically a step down transition going from receiver to barrel and the gasket sort of fills that void as well as the one in the stock inletting. It sort of locks the action into the stock and acts as a slight dampener as well as barrel support.

Sorry I don't have any pics and I am not going to pull an action out of a stock just for pics.

I've never had any torque issues with the action screws and the gasket in place. 21-24 in'lbs on any rimfire that is not pillar bedded.

455's do tend to prefer a little bit of upward pressure on the barrel. That was the reason I was given when I got my djdilliondon Tacticool skimmed and bedded stock from him. He does do custom CZ work if you are looking for somebody.

My gunsmith typically skim coats the 4" closest to the action under the barrel then free floats the rest on all my centerfires. It's an older technique, not without it's merits.
Click to expand...

Thanks for the details. Very helpful.
 
OK, got some of the rubber gasket the other day. Added a bit in but didn't clear things up. Got to messing with it and the stock was curving back in on the barrel too much, particularly where the barrel is thicker toward the receiver. Broke out the sandpaper and knocked the curve back some. Took off the front and rear sights while I was at it. Got the receiver back on and a dollar bill passes all the way back to the rubber piece without binding now. Back to the range at some point.
 
Now we are back on track. First 2 shots were nearly off the paper high. Finally got it worked down. Last 5 shots at 25 yards before I had to leave. This is more what I expect.


51f4cb4810ed5f0716291c76f568de35.jpg



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