Gunsmithing Scope base screws not straight

[hofhine1]

I really may be screwed but I thought I'd throw this out for some ideas.

I thought I saw this come up a year or so ago, but couldn't find it in the search, or was using the wrong keywords.

Problem, I have a 700 in .223 I bought, had barreled and set it in a McM stock I had laying around. First time at the range I had to put all the left that a NXS 8X32 had in it to get within about a half inch of POA.

I cursed the scope base manufacturer, because I knew that had to be the problem, the scope/ring assembly is proven, shoots fine on any other rifle, so, I get another base, swap out and head to the range.

Same, same , same.

I put the thing in the safe and try to forget it.

Yesterday I brought home a proven straightedge, pulled a Badger base off of another rifle and set the rifle in a rest and some bags to see if I can physically see the problem.

Yes, with the base screwed to the rifle, and a straightedge held to the side if the base, I can actually see the straightedge running off center of the flutes in the barrel. How much is hard to tell as I'm a one horse show right now, and lack the third and fourth hands required to try to get a measurement.

But to make things simple, I can assume that the screws are at least 22 MOA out of straight with the receiver, or bore.

Can anyone tell me if this were chucked up up straight in a mill, could the holes ever possibly be opened up enough to get them straight, or is it a lost cause to try on the receiver end, and go after fixing it with the scope base instead.

Thanks in advance for any help

sean

 

[pwc001]

Re: Scope base screws not straight

Yes, you can have the holes milled out and threaded for bigger screws. You can also send it back to Remmy, but they will take a long time, about 10 weeks, but that is a crap shoot, because you might get another bad one. Mine came back from Remmy great, but others have said they got back guns that are worse.

Good luck,
Pat

 

[Bronco]

Re: Scope base screws not straight

Adjustable rings.

 

[Al Nyhus]

Re: Scope base screws not straight

Don't assume it's the reciever base screws being out of line. You need to veryify the barrel/lug/reciever face fit to make sure that's not where the problem is before doing anything else.

A quick way to check this is: remove the bases and tape a piece of white thread at the rear of the reciever and center it exactly over the middle of the rear base screw hole. Now, extend it to the end of the barrel, drop it over the muzzle and tape it exactly over the center of the bore with a bit of tension on the thread. If anything is out of line, it's going to be pretty obvious where the problem is.

 

[pwc001]

Re: Scope base screws not straight

Good point, I missed the part about getting it being rebarreled, although alot of 700's have had the holes drilled wrong, so that would not surprize me if they are off. I also used the string method. Also a 4' level on the scope base.

 

[hofhine1]

Re: Scope base screws not straight

Al,
Thanks first of all, I like the thread idea, and pulled it off.

I don't know if the picture makes it as obvious as it was in real life, but I could plainly see the thread was not in the middle of the screws, I pulled the thread back through the bore to be sure it was centered, it has brand new Rock barrel and a new Holland lug, so I can only assume this was done correctly, and right out of the box it was shooting my goto 75 Amax load into 3/8 at a 100.

Obviously the next question(for me), is this a simple chuck it up and rebore and retap the holes to #8 screws?

Thanks again, I hate it when this happens.


sean

 

[Hateca]

Re: Scope base screws not straight

You are not showing the rear screw holes in relationship to the front. You can't assume the scope base holes are making the scope loose 22 moa of adjustment, there are other factors that can be involved with that, custom barrel or not.

You can't rely on what the outside of the barrel is telling you or the flutes in the outside of the barrel with regards to the scope base holes. All measurements and references must be taken using the bore, the outside of the barrel means almost nothing.

In the pic above the two holes are not off enough to have you loose 22 moa of adjustment at 100 yards, or even off enough for you to worry about. Making a call on whether or not you should have the holes re-drilled from pics is not an accurate way to make that call and you may spend money and still have the same issue.

 

[Wild_Bill]

Re: Scope base screws not straight

Have a gunsmith look at it i have seen barrels from top brands have a hole that the drill wandered these barrels can shoot aswell as any other barrel but they can make your rifle shoot sideways, have a the gunsmith that fitted the barrel check it over if the barrel has a bend in it it can be indexed upward so you use less elevation to get your zero, it will not loose accuracy but can do exactly what you are describing.

 

[Wild_Bill]

Re: Scope base screws not straight

PS if the scope holes were out they would have over .030" diference from the rear hole to the front hole check the barrel, Was the action trued? most rem actions are out a few thou on the face and if the bore is bent you will not fix it machining new holes.

 

[Al Nyhus]

Re: Scope base screws not straight

hofhine: I don't believe you've got a problem as regards the base screws. 22 moa is a huge amount for them to be off..and these certainly aren't off that much, if at all. Like HateCa pointed out, we don't know which way the bore is pointing. The thread method I suggested assumes the bore is pointing straight but it's no substitute for a qualified 'smith..still a quick way to check and see if anything is wildly wacho, though.

Time to have it checked by a good 'smith. -Al

 

[vinconco]

Re: Scope base screws not straight

I had a Remmy PSS that was off over 22 moa. Couldn't get a MK4 on paper at 100 yards. A straightedge told the story very quickly and the holes were redrilled. Rifle is now GTG and within 1/2 moa w/ the scope windage centered.

 

[Hateca]

Re: Scope base screws not straight

The majority, I would say 90%, of lost windage is the fact that the barrel bore has not been timed to TDC with the action.

If the barrel bore run-out has not been timed to the action at TDC or BDC you will loose windage very fast. If you are loosing 22 MOA of windage from scope base holes alone you would have trouble even mounting the base the holes would be so far off.

Now the holes could be a little off, the bore run-out could be a little off (even with a custom barrel) there could be some machine error, all that added up could cause you issues. But I will bet the run-out in that barrel has not been timed to TDC or BDC causing you the problem.