How Much Shim Under The Scope Mounts?

kopcicle said:
So, what's the problem?
Next...
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The next problem is that DNZ discontinued their +20 MOA mounts. I just realized I'm fighting an uphill battle because my rifle is an older, pre accu-trigger Savage with the flat back receiver, and there are few options for it. In fact, XTR rings are about the only option, and they're much more expensive than I had planned to spend.
 
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LoonWulf said:
run a full length pic rail and regular rings? be about 60-80 bucks....
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Yeah. It can be done. I have a 0 MOA rai, but I never used it because it obscures a lot of the bolt opening. I'm sure ejection would be no issue, but it will really impede loading. I could take a grinder and cut out what I need, though.
 
So what the heck. I had a piece of .030" aluminum on hand. Calculates out to about 27 MOA. Made a shim. Dressed the edges with a Dremel tool. Punched the holes with a drill press. Bada bing bada boom.

I didn't bed it with epoxy. It's temporary until I find out how well it works. If all goes as planned, I have some JB Weld I can use.

IMG_4157.jpg IMG_4158.jpg IMG_4159.jpg IMG_4160.jpg
 
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Sorry DB... `thought you were dealing with a Picatinny Rail 1-piecer rather than vintage/classic mounting where you can get under the rear mount.
Your solution above is right on.

Gotta start reading the fine print.....

.
 
Bedding shims to angle picatinny rails works exactly the same as it does for 1pc or even 2pc “non-picatinny” mounts.

Shimming without bedding ensures stress somewhere in the system, because you’re resting the scope or rail over a staircase instead of the same plane. OR it ensures inconsistent contact when done with 1 pc mounts, because if the mount doesn’t bend (introduced stress), then it’s not making solid contact - like laying a 2x4 timber down a flight of stairs, the timber only makes contact at the very edge of the tread plates, whereas we really want it making full contact. THAT is the purpose of bedding the shims, to fill those voids and replace supporting contact between the action and rail.

I might be a little surprised if none of EGW, Nightforce, or anyone else doesn’t still make 1pc rails for flat back Savages.
 
EGW and Talley both offer these, both pretty affordable.

Don’t forget - If you don’t like the encroachment of 1pc rails into the port space, if your rings don’t need that space, a little grind time to bevel the rail to match the port opens that access right back again.

IMG_5939.jpeg IMG_5938.jpeg
 
Varminterror said:
Shimming without bedding ensures stress somewhere in the system, because you’re resting the scope or rail over a staircase instead of the same plane. OR it ensures inconsistent contact when done with 1 pc mounts, because if the mount doesn’t bend (introduced stress), then it’s not making solid contact - like laying a 2x4 timber down a flight of stairs, the timber only makes contact at the very edge of the tread plates, whereas we really want it making full contact. THAT is the purpose of bedding the shims, to fill those voids and replace supporting contact between the action and rail.
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I understood your point early on. The only other solution would be to make a shim that is actually a wedge with an MOA that matched the thickness of the shim. Good luck doing all that math and fabricating that wedge in a home shop.

Like I said, this is just temporary. If I like it, then I'll go to the JB Weld. I can't brng myself to putting JB Weld on a rifle unless I'm really positive about what I'm doing.
 
D.B. Cooper said:
I understood your point early on. The only other solution would be to make a shim that is actually a wedge with an MOA that matched the thickness of the shim. Good luck doing all that math and fabricating that wedge in a home shop.

Like I said, this is just temporary. If I like it, then I'll go to the JB Weld. I can't brng myself to putting JB Weld on a rifle unless I'm really positive about what I'm doing.
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There’s nothing permanent about JB Weld unless you make it so. Kiwi clear boot cream on the action, and the bottom of the rail if you do desire, and it comes right off. Just like bedding a rifle into a stock - the rifle comes right back out, it’s just a matter of applying the release agent. I just added another QD swivel to my match rifle for my thumb rest this week, I left the Allen key used to install it in the port while it cured so the epoxy wouldn’t push out through the keyway, popped right out this morning - I’d just wiped it in release agent before installing. No fuss.

If a guy had the means to make an angled shim, they’d be better served to put less energy into simply milling the angle into the base. I used to fit “picatinny blanks” to a lot of rifles in the early days before pic rails were readily available - THAT was work which makes me glad we have the market we have now. But shimming and bedding is quick, easy, and foolproof.

In general, bedding rails is something we should be doing whether we’re shimming or not. Here’s an extreme example of why: if I had tightened this mount to the receiver, it WOULD flex and make full contact, and the rings would appear to not line up - and some guys might lap those rings, thinking they were out of round, or not machined properly for axial alignment. Instead, it would just be the bend in the rail causing misalignment, so I bedded this, perfect contact front and back, and the rings aligned perfectly on top with great scope tube contact, without lapping or bedding the rings. This base readily revealed its poor fit - not all rails do. But how many times have you seen rails removed from rifles and there is left shiny witness marks around the edges of the bases, with finish still remaining in the middle? That’s happening because the rail doesn’t fit, and is high at the edges, rubbing harder at the edges where it’s making contact than in the middle.

35801424785_ae62ee8009_o.jpeg
 
MEHavey said:
How does one do that with what is becoming increasing numbers of new rifles w/ integrated picatinny rails cast/milled directly in the receiver ?
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I’m not certain I understand your question - it appears you’re asking me how someone puts on shoes while they are already wearing shoes.

There is no need to add a rail to an action which has an integral rail, so it’s pretty obvious bedding an integral rail, as well as adding pop-can shims to an integral rail, aren’t applicable…
 
MEHavey said:
No, I'm saying that integrated rails require the shim to be
inside the ring/under the scope itself, not under the rail
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I’m not a fan of ruining scopes. You can crush your tubes if you like.

Lots of angled 1pc Spuhrs and Hawkins mounts out there - and Burris XTR Sig and Signature Zee rings on integral picatinny rails…

All of my integral rails are 20moa or more, by design.
 
MEHavey said:
Your response is unfortunate.
I asked for an alternative if/when (as the OP indicated),
there were no differentiated scope blocks available to him.

,
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There are one piece mounts with cant built in, some quite cheap and IME surprisingly straight. There are clamp on Pic rails with cant built in. There are rings that allow for adjusting cant without pinching scope tubes, which I've done. If shimming then epoxy bedding his rail is what he wants to do that will work also.

As VT said, lotsa options! just gotta find one that appeals

Ive used all of the above options at one time or another, and Ill say that I prefer a +MOA pic rail with regular rings over pretty much all the other options, but thats just what appeals to me.
 
Yeah. It works. That's 5 shots (including the top right flyer) in just about 2" x 2" at 300 yards. And I still have about 40 MOA of elevation adjustment remaining, of which I'll need 34-35 to get to 1000 yards.
IMG_4170.jpg

I shot this group using the 1.5 MOA subtension/hashmark/BD/whatever you call it with a center-mass hold. (1.5 MOA form this set up and bullet load should, according to the shooting calculators, be zeroed at 275 yards, so it looks like either the app is off, or my bullet is dropping about 1/5 inches over the 25-yard difference. Either way, I'll take it. Cairbou won't know the difference.
 
D.B. Cooper said:
Yeah. It works. That's 5 shots (including the top right flyer) in just about 2" x 2" at 300 yards. And I still have about 40 MOA of elevation adjustment remaining, of which I'll need 34-35 to get to 1000 yards.
View attachment 1160762

I shot this group using the 1.5 MOA subtension/hashmark/BD/whatever you call it with a center-mass hold. (1.5 MOA form this set up and bullet load should, according to the shooting calculators, be zeroed at 275 yards, so it looks like either the app is off, or my bullet is dropping about 1/5 inches over the 25-yard difference. Either way, I'll take it. Cairbou won't know the difference.
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The apps needs good data and sometimes truing to be accurate. Im usually at least a bit out before truing my data.
 
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LoonWulf said:
The apps needs good data and sometimes truing to be precise. Im usually at least a bit out before truing my data.
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I've heard of that, but I'm not sure what's involved int hat, or how it would impact other data in the app. For example, if I change the BC (by trial and error) until that 1.5 inches goes away, what does that do to the zero at 200 and point of impact at 400, etc. Same with changing MV. It seems to me that, if I change either of those data points, it will upset the dope card up and down the scale.
 
D.B. Cooper said:
I've heard of that, but I'm not sure what's involved int hat, or how it would impact other data in the app. For example, if I change the BC (by trial and error) until that 1.5 inches goes away, what does that do to the zero at 200 and point of impact at 400, etc. Same with changing MV. It seems to me that, if I change either of those data points, it will upset the dope card up and down the scale.
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If your zero'd at 2 that wont change, since thats your known input.
Truing the data will change ALL the drop #s the calculator spits out before and afterwards, but they should corelate more accurately than previously.
 
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