Scope mount shimming advice

Spur0701 · November 6, 2023, 07:10 AM

I've got a new Savage Mk II .22 that I mounted a Primary Arms ACSS .22 scope on, the mount was the one that came installed on the Mk II. I've run out of elevation adjustment and am still about 6 inches low at 50 yards and I want it on at 50. I know I should shim the back of the mount but am looking for any advice on how much and what to use for the shim. Any help is appreciated.

mehavey · November 6, 2023, 09:23 AM

You've got a 12 MOA problem there -- not insignificant.
Can you post a pic of scope/mounts set-up?

stagpanther · November 6, 2023, 10:12 AM

A .22 scope that you can't zero at 50 yds--probably the most common .22lr distance--something don't sound right with that.

I'd get an MOA rail/mount before shimming--which will never be consistent IMO in the long run.

tangolima · November 6, 2023, 10:22 AM

Something is not right. You shouldn't need shim. Did you try swapping the front and rear rings? Could it zero at 25yd?

-TL

Sent from my SM-N960U using Tapatalk

Spur0701 · November 6, 2023, 10:51 AM

Here's groups at 25 and 50....though the 50 is subsonic and the 25 super. In both cases the point of aim is at the top of the bullseye box at the 12 O'clock position as indicated by the chevron I put in with my marker. The base is what was on the rifle, the rings are Weaver that I had on the shelf that if I remember correctly came from Midway. Could the problem be the rings?

tangolima · November 6, 2023, 12:46 PM

It is way off. 3 possibilities; the rings, the scope, or the rifle. Try to eliminate by swapping components.

Rifle problem is bent barrel. I had one milsurp rifle that shot left and low by as much as 39moa. Eliminate the rings and optics first.

-TL

Sent from my SM-N960U using Tapatalk

mehavey · November 6, 2023, 03:32 PM

Looking at the pic, how much daylight do you show between
the scope bells (front & rear) and the picatinny rail itself ?

(Can you slide a playing card between them?)

tango1niner · November 7, 2023, 09:51 AM

Those picture of the rifle, mount, rings and scope set up leave much to be desired.

**4V50 Gary** · November 7, 2023, 11:47 AM

I knew one gunsmith who used business cards. I wouldn't b/c that would attract moisture and promote rust. I'd wax the metal (receiver and bottom of mount) and then use brass or aluminium (can). Both would also be waxed.

mehavey · November 7, 2023, 05:42 PM

Quote:

Shims...(etc)

I'm still waiting for the OP to tell us whether the Scope bell(s) are in fact resting on the rail.

**Unclenick** · November 7, 2023, 05:53 PM

Spur0701,

Per Tango1niner's comment, can you put an illuminated white background behind the rifle and retake the photo in profile so we can see the light gaps between the scope and rail? Of specific concern is whether the eyepiece bell might be elevated by sitting on the back edge of the rail.

MarkCO · November 7, 2023, 06:45 PM

Quote:

Originally Posted by mehavey

I'm still waiting for the OP to tell us whether the Scope bell(s) are in fact resting on the rail.

Me too.

jcj54 · November 8, 2023, 07:32 AM

You need taller rings

stagpanther · November 8, 2023, 07:57 AM

Quote:

You need taller rings

Best answer so far.

tangolima · November 8, 2023, 09:54 AM

Hard to tell in the picture. If that's what has happened, he may have bent the scope tube. A new scope may also be needed.

-TL

Sent from my SM-N960U using Tapatalk

stagpanther · November 8, 2023, 10:19 AM

Quote:

Hard to tell in the picture. If that's what has happened, he may have bent the scope tube. A new scope may also be needed.

Could be--I have a couple of PA ACSS scopes and they're pretty tough--my money would be on the rinky-dink scope rings failing before the scope.

If you zoom in on the rings you can see a notable gap in the front ring with the screws showing between the top and bottom halves, as well as what looks like an asymmetric wear mark on the scope tube in back of the front ring. Could be the rings simply weren't torqued correctly--or as others had mentioned the front scope bell be contacting the rifle/barrel/rail.

mehavey · November 8, 2023, 04:45 PM

My money's on the scope's front bell resting on the rail -- pointing the tube "up"
(I'd be glad to be proven otherwise w/ some pics)

MarkCO · November 8, 2023, 10:36 PM

Quote:

Originally Posted by mehavey

My money's on the scope's front bell resting on the rail -- pointing the tube "up"
(I'd be glad to be proven otherwise w/ some pics)

That is where I'd put money too, if we were betting.

Spur0701 · December 2, 2023, 10:52 AM

Problem solved, seems as if it was the rings, or the rings being too low. After the first couple of post I ordered a set of Weaver high rings from AMZ, swapped them out. With the holidays have only gotten it to the range once at 25 yards and am still testing which ammo it shoots best with.....thanks for all the help.

Blindstitch · December 14, 2023, 06:19 AM

The first set of rings are my #1 most hated type of rings. I've thrown a bunch of those away.

November 6, 2023, 10:12 AM	#3
stagpanther Senior Member Join Date: March 2, 2014 Posts: 11,806	A .22 scope that you can't zero at 50 yds--probably the most common .22lr distance--something don't sound right with that. I'd get an MOA rail/mount before shimming--which will never be consistent IMO in the long run. __________________ "Everyone speaks gun."--Robert O'Neill *I am NOT an expert--I do not have any formal experience or certification in firearms use or testing; use any information I post at your own risk!*

November 7, 2023, 11:47 AM	#9
4V50 Gary Staff Join Date: November 2, 1998 Location: Colorado Posts: 21,848	I knew one gunsmith who used business cards. I wouldn't b/c that would attract moisture and promote rust. I'd wax the metal (receiver and bottom of mount) and then use brass or aluminium (can). Both would also be waxed. __________________ Vigilantibus et non dormientibus jura subveniunt. *Molon Labe!*

November 7, 2023, 05:53 PM	#11
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,063	Spur0701, Per Tango1niner's comment, can you put an illuminated white background behind the rifle and retake the photo in profile so we can see the light gaps between the scope and rail? Of specific concern is whether the eyepiece bell might be elevated by sitting on the back edge of the rail. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle

December 14, 2023, 06:19 AM	#20
Blindstitch Senior Member Join Date: April 14, 2013 Location: Milwaukee, Wisconsin Posts: 2,694	The first set of rings are my #1 most hated type of rings. I've thrown a bunch of those away. __________________ NRA Lifetime Member

November 6, 2023, 07:10 AM	#1
Spur0701 Senior Member Join Date: February 2, 2005 Posts: 208	Scope mount shimming advice I've got a new Savage Mk II .22 that I mounted a Primary Arms ACSS .22 scope on, the mount was the one that came installed on the Mk II. I've run out of elevation adjustment and am still about 6 inches low at 50 yards and I want it on at 50. I know I should shim the back of the mount but am looking for any advice on how much and what to use for the shim. Any help is appreciated.

November 6, 2023, 09:23 AM	#2
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,903	You've got a 12 MOA problem there -- not insignificant. Can you post a pic of scope/mounts set-up?

November 6, 2023, 10:22 AM	#4
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,835	Something is not right. You shouldn't need shim. Did you try swapping the front and rear rings? Could it zero at 25yd? -TL Sent from my SM-N960U using Tapatalk

November 6, 2023, 12:46 PM	#6
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,835	It is way off. 3 possibilities; the rings, the scope, or the rifle. Try to eliminate by swapping components. Rifle problem is bent barrel. I had one milsurp rifle that shot left and low by as much as 39moa. Eliminate the rings and optics first. -TL Sent from my SM-N960U using Tapatalk

November 6, 2023, 03:32 PM	#7
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,903	Looking at the pic, how much daylight do you show between the scope bells (front & rear) and the picatinny rail itself ? (Can you slide a playing card between them?)

November 7, 2023, 09:51 AM	#8
tango1niner Senior Member Join Date: March 5, 2009 Location: NY Posts: 317	Those picture of the rifle, mount, rings and scope set up leave much to be desired.

November 8, 2023, 07:32 AM	#13
jcj54 Senior Member Join Date: February 28, 2011 Posts: 219	You need taller rings

November 8, 2023, 09:54 AM	#15
tangolima Senior Member Join Date: September 28, 2013 Posts: 3,835	Hard to tell in the picture. If that's what has happened, he may have bent the scope tube. A new scope may also be needed. -TL Sent from my SM-N960U using Tapatalk

November 8, 2023, 04:45 PM	#17
mehavey Senior Member Join Date: June 17, 2010 Location: Virginia Posts: 6,903	My money's on the scope's front bell resting on the rail -- pointing the tube "up" (I'd be glad to be proven otherwise w/ some pics)