What are 8-40 screws

Re: What are 8-40 screws

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Stick Around</div><div class="ubbcode-body">Most receivers are 6-48,8-40 is a bump in fastener diameter.

You want 6-48's or "regular". </div></div>

i too was wondering this. was looking to get a badger base, but it was an 8-40. is it a larger screw?
 
Re: What are 8-40 screws

For SAE/English sized fasteners, bolts/screws smaller than 1/4" (diameter) are named according to a "number" instead of fractions of an inch. In the common land, the biggest "number" screw is #12, and the smaller the number, the smaller the diameter.

You are asking about a number 8 screw, with 40 threads per inch.

I think most rifles tend to come tapped for a 6-48, which is smaller than 8-40. My Remington 700 in 338LM is an example of a rifle tapped for the larger screws, 8-40. In this case, a scope base with the holes drilled out a little extra was required, because an 8-40 screw doesn't fit through a hole drilled for a 6-48.

Hope this helps. LOTS more info out there on the web about fasteners. This wasn't even a "101" class.
 
Re: What are 8-40 screws

ok, thanks!

hopefully this Warne steel base is a good one! I really don't want a 20moa. I have enough elevation on the scope I'm getting...
 
Re: What are 8-40 screws

If you are running a heavier caliber you might consider having a smith retap your receiver for 8-40. As stick stated most rifles are tapped 6-48 and will state if they are otherwise.

Here Larry the guru of all gun bubbas splain's a bit http://youtu.be/LLMFtwS2bpQ

I strongly recommend this be done by a competent smith, you tap into your chamber and you now have a tomato stake.
 
Re: What are 8-40 screws

For giggles a guy can go 8-40 and a lugged base.

HardCorp.jpg


Reality is,it's been a long while since I've failed 6-48's and that was ala the notoriously shitty Leupold S/S fasteners(pre Torx) and aboard my 378Wby.

I'm routinely comfy in 6-48's,but have been known to go overboard.(grin)
 
Re: What are 8-40 screws

6s to 10s... wow that's a huge jump in size.


6s are more than enough for 99% of the guns on the market with a quality bolt. Unless you're hunting elephants 6s will be fine on most guns.
 
You must have one that matches your barrel OR re-tap the barrel for the larger screw.
I have a 112 Savage 338 Lapua Mag and it is drilled and tapped for 8-40. I cant go back and I cant find bases that will fit.
 
yes, but I cant find the 8-40 screws

Fastenal, your local Ace hardware, Brownells, any of the manufacturers of scope bases.
Put up a WTB ad on the Hide.
Maybe the internet?

They aren't hard to find.

Edited to add:
Look right above, ^^^^ up there^^^^.

Links provided for you so you don't have to put any effort whatsoever into getting stuff for yourself.
 
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