Not enough down travel to zero scope
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MudRunner2005
Well-Known Member
I ran out of top adjustment on my 5R .308 with a 20MOA base and had to swap to a 0MOA base and everything works out now.
westcliffe01
Well-Known Member
Wow, I looked on the manufacturers website and they do not seem to regard it as important to notify potential customers of the scopes internal travel. Its not listed anywhere, even on the scope manual that I had to find in a google search since there is no obvious place to find it on the web site.
So, in the absence of a specification, have you figured out what the internal travel is ? How many minutes per rotation of the elevation turret and how many total from top to bottom ? If the travel is around 40min (like many of the Nikon scopes) then clearly a 20 min rail is going to be a problem
You could consider putting a shim under the front of the rail (like 1 layer at a time of electrical tape) until you get back into territory where you have got surplus elevation left over. Just don't tighten the front rail screws tight, just enough to maintain contact. Once you work out your shim, then leave the shim in place and put bedding compound between the rail and receiver. You might want release compound between the rail and the receiver if you are likely to need to remove it often, else let it bond to the action.
You don't want to crank down on any of the screws but the back ones where you don't want any "lift" you would snug down tighter than the front. Put the scope on temporarily to verify that you are in the adjustment range. Then let the bedding set up. Clean up any excess compound right away so it looks neat. Give it 24hrs to set up fully, then remove the screws and apply blue loctite and tighten to the recommended spec (now that the bedding compound is cured and can support a load).
Most likely the LR scopes have more travel since they were apparently designed for longer distance shooting...
So, in the absence of a specification, have you figured out what the internal travel is ? How many minutes per rotation of the elevation turret and how many total from top to bottom ? If the travel is around 40min (like many of the Nikon scopes) then clearly a 20 min rail is going to be a problem
You could consider putting a shim under the front of the rail (like 1 layer at a time of electrical tape) until you get back into territory where you have got surplus elevation left over. Just don't tighten the front rail screws tight, just enough to maintain contact. Once you work out your shim, then leave the shim in place and put bedding compound between the rail and receiver. You might want release compound between the rail and the receiver if you are likely to need to remove it often, else let it bond to the action.
You don't want to crank down on any of the screws but the back ones where you don't want any "lift" you would snug down tighter than the front. Put the scope on temporarily to verify that you are in the adjustment range. Then let the bedding set up. Clean up any excess compound right away so it looks neat. Give it 24hrs to set up fully, then remove the screws and apply blue loctite and tighten to the recommended spec (now that the bedding compound is cured and can support a load).
Most likely the LR scopes have more travel since they were apparently designed for longer distance shooting...
Go to burris signature rings and you and use the inserts to get the exact MOA you need. they have 0, 5, 10 and 20 MOA inserts and you cna mix and mtach to 40 MOA.
bigngreen
Well-Known Member
No, you have a 20 MOA cant rail which means it's higher in back than front. I respect BountyHunters advice but the Burris signature rings will not last for ever on a RUM, I seen several just not be able to take the punishment, love them for smaller stuff but not for the RUM+ rounds.
westcliffe01
Well-Known Member
If the 20MOA rail is installed as it should be, it will tilt the scope downwards by 1/3 degree. Then when you look through the scope, the barrel is raised by 1/3 degree. That allows you to shoot further with a given amount of internal scope adjustment.
1/3 of a degree is not much. You may only need 1 strip of the electricians tape to get you back within the working range of your scope. But given the fact that you are not shooting a 223, the mounting rail would need to be properly bedded in that position. I am assuming you have a one piece rail, that way the rings would still be in perfect alignment with each other and the scope. So you just have to fill the gap that is created between the base and the receiver with bedding material.
In my opinion, it would be the cheapest and most robust solution to the issue while giving you as much travel as you can possibly get out the scope. But don't forget the final step of loctiting and torquing the base screws.
1/3 of a degree is not much. You may only need 1 strip of the electricians tape to get you back within the working range of your scope. But given the fact that you are not shooting a 223, the mounting rail would need to be properly bedded in that position. I am assuming you have a one piece rail, that way the rings would still be in perfect alignment with each other and the scope. So you just have to fill the gap that is created between the base and the receiver with bedding material.
In my opinion, it would be the cheapest and most robust solution to the issue while giving you as much travel as you can possibly get out the scope. But don't forget the final step of loctiting and torquing the base screws.
geargrinder
Well-Known Member
Quit shooting at 100 yards. Zero your rifle further out.
Or, use your mildots. Set your zero on the bottom of your top post.
Or, use your mildots. Set your zero on the bottom of your top post.
We were just breaking in the barrell. We were using the second dot up on the mil dots and it was still 5 inches high at a 100yds. Even if I zero it at 2 0r 300 it would still be shooting to high. I will try a piece or two of electricians tape and see if that works.
westcliffe01
Well-Known Member
Just remember you just want light pressure on the tape to make contact - then check where the scope is pointing at and if you've got control over the elevation for zero. Thats a hard hitting rifle and the rings/rail have to be 100% secure before you fire it.
MudRunner2005
Well-Known Member
Swap to a 0 MOA base.....It will solve the issue. Mine did that, and by swapping the base it corrected the problem and brought it down to be able to zero @ 100.
Lefty7mmstw
Well-Known Member
I'd actually go drink a can of coke and cut the side material out of it with a pair of tin snips making a few shims that will mate with the bottom of your bases. Stack them in one at a time until you can zero the scope with a couple of moa breathing room to spare. Then I'd put a drop of blue loctite on each of your base screws and torque properly. You won't have to work with bedding compound and it's a permanent 0$ fix. I've had to do this with a ruger 7 mag to clear a scope once (that shim went in the rings) and a win 375 because the scope was out of adjustment room once. Neither moved a bit over hundreds of rounds.
Greenleader
Active Member
- Joined
- Jun 1, 2013
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- 37
That optic should have at least 80 MOA of adjustment, I want to say it has 100 MOA. I did a search and found people having similar issues with the TRS-1.
Matt
Matt
