Right now i am about 4" low at 100yrds. I have my scope adjustment all the way up and am out of adjustment room. Do i need to shim the front of my scope base or the read. A local Gunsmith say shim the front but i dont think that is right. any help would be appreciated!
Help needed. i am out of scope adjustment and i am still shooting low
- Thread starter kgpcr
- Start date
Mobius
Active member
Need a bit more info. What caliber are you shooting? The arc is important to know to determine if you are hitting the top of the arc at 100yds or if not which side of the arc you are on.
I'd sure check your scope rings. Sounds to me like your front ring is too high or your rear ring is too low.
Try this. Take the top off both rings and put your scope back into position. Now press down with one finger on the front, then the rear. If either of those causes the scope to lift, you have uneven height in your rings. Easy fix, whether shimming front or rear, or replacing one of the rings.
Try this. Take the top off both rings and put your scope back into position. Now press down with one finger on the front, then the rear. If either of those causes the scope to lift, you have uneven height in your rings. Easy fix, whether shimming front or rear, or replacing one of the rings.
1Cor15:19
Well-known member
This is not an unusual problem to have with production rifles. To increase the range of useful adjustment and raise the POI to your POA you'll need to "shim" the rear ring/base. Depending upon the rifle/scope combo there are several ways to make it happen.
Mobius
Active member
OK, so likely the zero point is the top of the arc. In that case, the guys above are right. The scope is too high on the front. Is it possible that your rings are swapped? Just a thought. You may have a set of rings that are designed to cant the scope and you have the rear ring in the front and vice versa? Like the guys about said, raising the rear of the scope will raise the POI of the bullet. Raising the front will lower it.
And a really good thought! Pretty common mistake.
Eastwoods
New member
There is probably a better way, but, I have had good luck with putting 2 layers of black electrical tape on the inside bottom half of the ring (rear ring in this case). That is , if you haven't swapped rings by mistake etc., and it is an actual manufacturing inequity.
Mobius
Active member
And if that IS the problem, begs the question, who the heck is that gunsmith? LOL.
Do not put shims inside the rings. Doing that will effectively reduce the diameter of the ring and crush the scope tube. The shims should go under the base. Usually about .030" to .040" will do the trick and bring your adjustment to the center of its range. Caliber doesn't matter at 100 yards. Any well equipped gunsmith should have precut shims on hand.
PRDATR
Active member
Yeah he is just peddling parts so move on down the road.
We need to know the rifle, make and model of the rings and bases and the scope. Post some pictures too because either the scope is hosed or something isn't installed correctly. Don't shim it.
Actually, everything can be correctly installed, and nothing "hosed", and still be out of adjustment. Over the years, I've worked on many rifles that were out of spec on the bridge height and needed shims to be correct. Another possibility is a scope that has been bent, usually by the front bell being pushed down towards the barrel. That will cause a high point of impact. Scope is still functional, just needs shims. 70's and 80's vintage Winchester m-70's were bad that way for a while, as far as the rear bridge being incorrect.
1Cor15:19
Well-known member
Listen to gunbugs, he knows about what he speaks. It is not uncommon for the specs for bridge heights to have significant variation. Many rifle designs have been in production for 50+ years and that almost certainly dictates some inconsistencies. Typically, the variance isn't a problem, but it can be for a number of reasons. Shimming bases isn't a bad way to go, though to raise the elevation you'll shim the rear base--not the front. Burris makes concentric inserts for their Signature rings that allows as much as 40 MOA (-20 in the front and +20 in the rear ring). I've mounted several scopes that way so as to extend the possible zero range when spinning turrets. I haven't, but I know several fellows that'll shim the bases, in addition to the Signature rings, to extend their range even further. Shimming is common practice among those in the know and a very easy fix.
sep
New member
Beyond all the sage advice you have already received, are you sure you scope is okay?
Smitty of the North
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pinehavensredrocket
New member
advice from gunbugs and others make perfect sense...but there is another fix not yet mentioned. sometime we mount scopes on several rifles and never " recenter" them. riflescopes do not have unlimited adjustment, so remove your scope caps and turn the elevation dial completely up until it stops. then turn it all the way back counting the clicks or hashmarks. divide the number by two and move to that number ( which will be center ). do the same for your windage dial.
doing this "recenter" will give you the most adjustment possible in your scope.
personally i like leupold and redfield mounts which allow rough windage adjustments from the rear mount, then just fine tune with the scope.
doing this "recenter" will give you the most adjustment possible in your scope.
personally i like leupold and redfield mounts which allow rough windage adjustments from the rear mount, then just fine tune with the scope.
If your adjustment is bottoming out it is not going to help any by recentering. As Gunbugs said shims will work for your problem. I have made shims out of a soda can by cutting to size with snips then using a hole punch to punch a hole for the screws. You can stack the shims to get the thickness you need.
