Gunsmithing Dumb mistake with a Nightforce base

[81mike]

Once again my impatience has set me back. Here's the deal:

I was planning on mounting my NF 20 rail on my 700p 338lm and as you all know the receiver is tapped for 8-40, but the rail is drilled for 6-48...the problem is I let a "buddy" "open the holes up"...when I picked it up, to my dispair, I was handed a "sorry, buddy" and a rail that an 8-40 screw will smoothly slide straight through...apparently he wasn't familiar with a counterbore

The fits have been thrown and the apologies accepted...now I am hoping for some expert help.

Does anyone know where I can get some 8-40 screws with, perhaps, an oversized head so that a qualified machinist can salvage my rail?

Thanks for any responses and directing them to "Dumbass" would be more than appropriate. Thanks guys.

 

[USMCj]

Re: Dumb mistake with a Nightforce base

goto your local hardware store and look through their screw selection to see if they have a screw with a larger head.

 

[packratt]

Re: Dumb mistake with a Nightforce base

Try McMaster-Carr

 

[81mike]

Re: Dumb mistake with a Nightforce base

I tried Fastenal and all they had was 8-32's

 

[Victor N TN]

Re: Dumb mistake with a Nightforce base

Can you move 3/8" in one direction or the other and come up with "fresh" metal and just redrill it? If I were you I would do it on a mill where I could make it a precise move.

But of course, it's your rifle and you're the one that has to live with the consequences.

 

[81mike]

Re: Dumb mistake with a Nightforce base

That has definately been discussed...we are thinking about taking the back of the rail, machining the recoil lug off, moving back and re-drilling...damn...haste makes waste

 

[81mike]

Re: Dumb mistake with a Nightforce base

Thanks packratt...any opinions on the flange socket? Doesn't look strong enough to me, but maybe someone knows

 

[AMAC]

Re: Dumb mistake with a Nightforce base

if it was mine I would throw it in the odds and ends drawer and buy another rail.

 

[81mike]

Re: Dumb mistake with a Nightforce base

Yep, thought of that too...maybe I will go ahead and get the 40 rail...thanks

 

[AXEMAN]

Re: Dumb mistake with a Nightforce base

whats it made of? have the holes tig welded shut. redrill. that way you can use the recoil lug.

 

[chpprguy]

Re: Dumb mistake with a Nightforce base

What size is the thru hole in the rail now?
I have some tapered/countersunk 8-40's that the head is larger than a normal 8-40 torx screw.....

 

[RADcustom]

Re: Dumb mistake with a Nightforce base

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AXEMAN</div><div class="ubbcode-body">whats it made of? have the holes tig welded shut. redrill. that way you can use the recoil lug. </div></div>

This is what I would no matter what it's made of.

 

[gunny]

Re: Dumb mistake with a Nightforce base

Try Brownells for the screws

 

[chpprguy]

Re: Dumb mistake with a Nightforce base

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RADcustom</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: AXEMAN</div><div class="ubbcode-body">whats it made of? have the holes tig welded shut. redrill. that way you can use the recoil lug. </div></div>

This is what I would no matter what it's made of. </div></div>

This should be a last resort,
easily do-able, but you risk warpage and you will have to reprofile the mating surface of the base...

 

[RADcustom]

Re: Dumb mistake with a Nightforce base

Maybe so, but it would be (IMHO) better than the over-sized screw solution.

 

[chpprguy]

Re: Dumb mistake with a Nightforce base

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: RADcustom</div><div class="ubbcode-body">Maybe so, but it would be (IMHO) better than the over-sized screw solution. </div></div>

I'm not an engineer (just a welder)
so I can't be sure, but I'd think oversized countersunk screws would be strong if the rail was machined correctly for them....
my opinion and a hat would barely qualify me to work at McDonalds though......

 

[Revenge Seeker]

Re: Dumb mistake with a Nightforce base

a flat head screw's max OD is larger than a standard SHCS, so a 60* countersink to desired depth should work just fine.

 

[subgunr]

Re: Dumb mistake with a Nightforce base

If the screw in question was a #8 SHCS. A BHSCS has a larger head dia. The FHSCS needs a 82 degree or 90 degree countersink depending upon the screw. If the rail is steel,I dont think I would "weld the holes up" and try to re-drill in the same place . Some of the rails are made from 40XX steel and welding will heat treat the area and you will need a carbide drill to get thru it. my 2 cents

 

[81mike]

Re: Dumb mistake with a Nightforce base

Gentleman, thank you all for your insights. I am still considering the oversized screw solution, but the problem is "where do I get them?". I have tried Fastenal, Grainger, Brownells, McMaster, etc. and nothing seems to look right. Hell I even emailed a company last night to see if they would make me a #8 screw with #10 or #12 heads.

I think I might try pleading mercy from NF but I am pretty sure what they are going to say, but F-it it's worth a shot.
Thanks again guys and if you have anything else I am all ears.

 

[chpprguy]

Re: Dumb mistake with a Nightforce base

If you tell me the hole size in the base, I may have some countersunk screws you can have...


Andy

 

[Top Cat]

Re: Dumb mistake with a Nightforce base

That has got to be a big hole in the base, like 1/4" ?, but don't panic yet...

Find a larger diameter screw that fits the new hole size snugly, whatever that is now. All that has to be done is to turn the part of the shank that enters the receiver to the correct diameter and thread it to 40 tpi.

Countersink your base to the correct angle to receive the screw head. You can also use a larger screw and turn the threads off the large part of the shank body to fit the hole. Either way, as long as the shoulder is a hair short so it doesn't jam on the receiver you are good to go.

A lathe would be handy, but if you are handier than your buddy, you can turn the screw with a drill press or hand drill and a file. Calipers are your friend.

Not really that complicated, but maybe some kind soul on here would make you a few.

The larger diameter screws would actually be a stronger system. Tell everyone you redesigned the screws for greater recoil area.

TC

 

[81mike]

Re: Dumb mistake with a Nightforce base

Just wanted to thank everybody for their input regarding the repair of my NF 20 rail, especially you, Top Cat. We used the stripper bolt method that you recommended and it worked like a charm. My only cost was an 8-40 tap from McMaster-Carr, but it was worth it as I learned a lot out of this little project.

Thanks again fellas, your insights and willingness to share your experience and knowledge are greatly appreciated.

Semper Fi,
Mike

 

[Top Cat]

Re: Dumb mistake with a Nightforce base

I'm glad you got it fixed...if you get a chance to post some pics of the solution, I'm sure the members here would find the solution interesting.

And you're welcome...as they say, a good idea is worth it's weight in beer...

TC

 

[81mike]

Re: Dumb mistake with a Nightforce base

I will be sure to get some pics up as it may be helpful to others. Thanks again.