Scope shimming.

[richhodg66]

During experimentation with the 311413 in my .308 bench gun, I ran out of up adjustment on the scope. POI is about an inch and a half low of POA at 100 yards with the load at the sweet spot for accuracy with Blue Dot. Increasing it from there caused groups to open up quite a bit.

Shimming the rear ring to raise the rear of the scope seems like the thing to do, hoe best to go about that? Some kind of shim in the ring? Under the svope base itself? What material to use and how thick to start with?

That bullet is notorious for needing to be pushed slowly if accuracy is to be maintained and I seem to have found that out.

 

[Brad]

Pop cans can make good shims for this.

I have placed them under scope in ring but prefer to place under base.

Best course of action is Burris signature rings with the inserts- you can get offset inserts and they give a huge amount of options

 

[fiver]

i used some roof flashing it come in at about 12 thou or thereabouts.
i just trimmed a piece wiped a little rosin on it and put it under the scope, but now i don't remember if i used 1 or 2 to get it down the full 8"s i needed at 100yds.

 

[JonB]

Best course of action is Burris signature rings with the inserts- you can get offset inserts and they give a huge amount of options

I am a BIG fan of the Burris Sig rings with inserts.
Besides the shim-like adjustability, they are plastic and don't mark/scratch a expensive scope.

 

[Cadillac Jeff]

I sacrificed a old feeler gage, that way I had a clue how high I was raising it.

 

[RicinYakima]

Ideally, you wan to get it up to center of adjustment, so 0.025" is not out of line.

 

[obssd1958]

I used some scrap cartridge brass. Anneal it in a flame and you can cut it with side cutters.

 

[Tomme boy]

I don't shim rings or mounts. I don't want to dent my scopes. I get the Z rings or a 0,10, 20 moa scope base. Or get some lower rings if you can fit them.

 

[richhodg66]

OK, I have a set of the Burris signature rings on the way. Hopefully, that will take care of this. With low niode shooting, this could become a problem on other rifles, although this is the first time for me.

 

[Ian]

I haven't bought any in a while, but have bought many Burris Signature ring sets and they all came with neutral inserts. There was an additional kit i had to buy with three sets of matched inserts with iirc 5, 10, and 20 thousandths offsets. The frustrating thing was finding the offset insets in stock when I needed them.

In my opinion they are the best rings made whether you need the offset or not.

 

[Tomme boy]

Yep you have to buy the kit to get the extra inserts. When I built a bunch of Mausers, the scope mounts seemed to never line up with the bore of the barrel. Always had to use the inserts to correct it. Some of the military mausers were WAY off. I had one Turk small ring that the barrel was angled to the left about 5° The receiver was straight, the threading was done canted.

 

[CWLONGSHOT]

Just went thru this with a Ruger. 20 moa base did the trick.
Maring the scope when shimming is /was concerning.

Another time I upgraded scope W/30mm tube. That worked too. (usually more size means more adjustment )

Burris rings can be a blessing.

CW

 

[300BLK]

I probably have 6 or 8 sets of the Burris Signature Zee rings (work on Weaver bases or Picatinny rail) and all have been provided with adjustment inserts. I have several rifles with 20moa tipped picatinny rails besides.

 

[Petrol & Powder]

OK, I have a set of the Burris signature rings on the way. Hopefully, that will take care of this. With low niode shooting, this could become a problem on other rifles, although this is the first time for me.

/\ Unquestionably, "THE solution". /\
Elegant, simple, durable.

 

[JonB]

Another bonus to Burris Sig rings with inserts, is scope alignment in the rings.
I recall reading about "truing" scope rings(sanding/filing/polishing) especially rings mounted in a two piece mount.
The Burris inserts are convex and fit into the sig rings which internally are concave...so the inserts can "roll" or move into alignment during the tightening...you gradually tighten the front, then back, then front some more, than back some more...until tight, and the scope trues itself as rings are tightening.

 

[JonB]

OK, I have a set of the Burris signature rings on the way. Hopefully, that will take care of this. With low niode shooting, this could become a problem on other rifles, although this is the first time for me.

I haven't bought any in a while, but have bought many Burris Signature ring sets and they all came with neutral inserts. There was an additional kit i had to buy with three sets of matched inserts with iirc 5, 10, and 20 thousandths offsets. The frustrating thing was finding the offset insets in stock when I needed them.

In my opinion they are the best rings made whether you need the offset or not.

Rich,
Ian is correct, the sig rings only come with neutral inserts, you will likely need the offset kit.
If you have trouble locating the offset insert kit, I may be able to help you.

 

[Ian]

I might have some spares, been a long time since I looked in my scope ring box though.

 

[glassparman]

Gonna try the Burris rings. I have an M1A clone with one of those smithless scope mounts. It sets off to the left side and this thing shoots way off to the right and even with the scope set all the way to one side, I still can't get it dialed in. I think this is the answer!

Thanks for the discussion!

 

[richhodg66]

I also ordered the kit of inserts so I should have what I need soon.

 

[Ian]

Gonna try the Burris rings. I have an M1A clone with one of those smithless scope mounts. It sets off to the left side and this thing shoots way off to the right and even with the scope set all the way to one side, I still can't get it dialed in. I think this is the answer!

Thanks for the discussion!

There is only one M1A scope mount that's worth a damn for sure and another that looks to me to be just as good and lower profile. CASM is the known good and Bad Ace Tactical makes one similar but lower and has a stripper clip tee nut attaching point. Both are elevation adjustable.