Options to deal with Remington Receiver with 8-40 scope base threads

[jepp2]

I found out the recently acquired Remington 700 has been converted to 8-40 threads on the receiver base mounts. I tend to use Leupold QR bases, since I move scopes around a good bit. Since I don't have access to much, what are the options to utilize the Leupold scope bases?

Options I'm aware of:
-Warne Maxima M912-873 bases that come with 8-40 screws - nobody has this base in stock
-Brownells has a Remington 700 heavy duty Picatinny base. but this doesn't allow Leupold QR rings

So I really want to use the Leupold scope bases, but anything short of drilling out the holes and counterboring the recess?

 

[jepp2]

Buy some 8-40 screws, Brownells or (my local) True values now carry a good selection of gun screws.

Ok, but they don't fit through the holes in the bases, and the heads are too big to fit.

 

[jepp2]

How do you know they wont fit?

I tried them. And if you read this article, you will see what is required. I'm looking for a simpler way.

https://rifleshooter.com/2014/10/remington-700-8-40-scope-base-conversion/

 

[Riesel]

Is it possible to drill the bases to the correct size and then turn the screw heads down to fit in the #6 counter bore hole? I think I've done this in the past using a drill to turn the screw and a flat file to cut it down.

 

[jepp2]

Is it possible to drill the bases to the correct size and then turn the screw heads down to fit in the #6 counter bore hole?

I'm sure I could drill the clearance hole in the base. I "read" somewhere where someone used the drill like you suggest, but spun the head against a Dremel abrasive wheel (spinning) to reduce the diameter. Cheaper than having to buy and counterbore and find someone to use it. I'm surprised a file will cut the head. They are really hard.

 

[Boyd L.]

....So I really want to use the Leupold scope bases, but anything short of drilling out the holes and counterboring the recess?

I think your best option is to obtain two drills. The first with the appropriate shank diameter (#29, I think), and two, a drill of appropriate diameter to permit the head of the screw to pull up against the counter bore shoulders.
Set up the base level and centered, punch the shank diameter. Without moving the base or base holding it, switch to the counterbore bit. Drill to the premeasured depth.
Rinse, repeat three more times.

 

[BR7.62]

Badger makes pic rails for 8-40 screws.
I think if you were gonna modify a rail like mentioned youd want to be using a mill to make sure it's perfect.

 

[jepp2]

I think if you were gonna modify a rail like mentioned youd want to be using a mill to make sure it's perfect.

I agree with that. Somehow my $59 Harbor Freight drill press with no vise isn't get the job done.

 

[Ledd Slinger]

Yeah I think drilling and counter boring is really the best way to go. I've converted all my factory 700s to 8-40 base screws. I just open up any base I want using a 11/64" drill bit then counterbore with a chamber bit that fits the 'oval' head torx screws I use. I also keep a good supply of various length screws on hand.

You could use a regular counterbore bit for the flat Fillister head screws. I like the oval heads better because the bore leaves more metal and the screw heads have better contact.

Here's my little scope base mod kit. I do use it in my milling machine, but I have done them in a drill press and it turned out fine. Mill is definitely the way to go tho.



Good screw kit to keep on hand

 

[RWO]

Everybody wants to use filister head screws. IMHO Weaver's system is better. Their base screws have a 45 deg taper on the under side of the head. This matches their counterbore: https://www.brownells.com/gunsmith-...r-8-40-sight-screw-counterbore-prod25485.aspx

A regular machinist's countersink is usually 82 deg., so it does not match the Weaver base screw head. Neither does the usual drill point angle of 117 deg. If you have a drill grinder, it usually has an adjustable drill point angle, so it's easy to put a 90 deg point on a drill to cut the counterbore A piloted counterbore is better, but is more costly.

RWO

 

[Ledd Slinger]

Everybody wants to use filister head screws. IMHO Weaver's system is better. Their base screws have a 45 deg taper on the under side of the head. This matches their counterbore: https://www.brownells.com/gunsmith-...r-8-40-sight-screw-counterbore-prod25485.aspx

A regular machinist's countersink is usually 82 deg., so it does not match the Weaver base screw head. Neither does the usual drill point angle of 117 deg. If you have a drill grinder, it usually has an adjustable drill point angle, so it's easy to put a 90 deg point on a drill to cut the counterbore A piloted counterbore is better, but is more costly.

RWO

Yeah I don't like fillister screws. The flat head leaves wiggle room for the base to move in the slightly wider flat counterbore. The 45 degree weaver head design, aka: "oval" head, is way better for getting a solid weld of scope base to receiver. Locks everything down super tight.

I just picked up a 1/4" - 45 degree counter sink on Ebay for countersinking the oval head screws. Works perfect for the larger head on 8-40 torx screws and matches the angle. I drill my hole with an 11/64" drill bit in the mill, then remove the bit and arbor and install my angled countersink with its arbor. As long as you don't move the table, the countersink bit will remain perfectly centered over the hole you just drilled. No pilot needed.

For flat counterboring, I only use piloted counterbores. Well worth the extra money because the swappable heads on my set don't always run perfectly true. The pilot ensures the counterbore bit stays straight.

 

[jepp2]

This is all very helpful information for me. Thanks to everyone!!

 

[Ledd Slinger]

While on the subject of fillister and oval screw heads.....

I just went to install this PT&G bottom metal that arrived yesterday. Bottom metal is nice and magazine fits perfectly, but Houston we have a problem!

Pic of the bottom metal. Note the action screw recess angle.




Pic of the action screws that come with the bottom metal Ummmmm...I'm ot the fartest smeller, but I don't think this is gonna work Dave!