Screw Size for Weaver Scope Rails ?

I am trying to find a rail for a Sporterized 7.7mm Arisaka that has been
converted to 300 Savage. I bought it at a Military Surplus store for $130.

It was drilled and tapped, but who knows when !?

The receiver is straight and level front to back and has holes pre-drilled
and Tapped for the Weaver screws.
I measured the holes with my trusty digital micrometer.

http://www.mynetimages.com/9a8722f6f9.jpg

Having the dimensions of the drilled holes doesn't do me any good, though,
as nobody knows where to look.

All the rails are made for specific rifles and who knows what the guy who drilled
these holes used for a rail ? !

All the stores where I can look for rails have the damned pegs behind the
counter and clerks who are as dull as a fence post soaked in the rain.

I have found something that I want to try, but it requires longer screws
than come with Weaver rails.

My question is - what are the specs of the screws that come with Weaver rails ?

I think they are Metric, but am not sure - I am not a machinist and am trying
to keep the expenses at a minimum !

What thread size are they and where could I obtain that thread size, but
longer than what Weaver provides ?

DoctorBill

Probably #6 x 48 tpi. Brownell's has them, in various lengths.

RRR

Bill, I don't know what you have there but the picture looks like you have 2 different sized screw holes, the rearmost hole on the front rev'r ring looks smaller than the other 3. The foremost screw is also out of line with the other 3 when I hold a straight edge up to the pic. It looks to me like the 3 larger holes are 8-40's and the smaller one is 6-48. Maybe it's just the picture angles and lighting.

He may not have used a one piece base, but the more common 2 piece bases.

I dont think it was one piece as most time the spaceing on one piece is same. Your best bet is first see what the thread size is. would say work was done in the States and if so it not metric.
Your next problem . will bet you cant move scope far enough for correct eye releif. That may be why mounts are missing

looks like you many need a 48 or 68 for rear and like a 47 for front. I dont know the radis so hard to know which one

First - all the four holes have the same size and thread.
The screws from various Weaver Rails all fit those 4 holes.
If the screws are 6-48, I will go to a fastener store here where I live:
http://www.fastenal.com/web/home.ex
and buy some longer ones.
What class of bolt (only hundreds!) would I ask for ?
http://www.fastenal.com/web/search/p...N-gj4wap&Nty=0
http://www.fastenal.com/web/search/p...N-gj4wbr&Nty=0


Second - at the front of the receiver, the middle hole is the standard Arisaka
gas vent hole - that is why it looks larger.
Third - Are all the two piece Weaver Bases of the same hole distance apart - front and back ?

Forth - I would like to set up a Red Dot scope. I was wondering if the two front holes
would be sufficient to hold a one small rail - Red Dot Scope all by itself.

Here are some bases I found on
http://www.theriflescopestore.com/

Notice the different hole widths one to another base.
Differnt heights, though.
This is confusing and very frustrating !

http://www.mynetimages.com/6406152a7a.jpg

I E-Mailed the Rifle Scope Store and asked them about the Arisaka setup...

DoctorBill

PS - Edited in later......Making progress.....
......I may have found the Weaver Bases I need !
Weaver number 55 (rear) and 46 (front) with a shim...
Where do you buy shims - does Weaver sell them ?

FYI - Nice web site for scope mounting:
http://www.charm.net/~kmarsh/mounts.html#twoversus

I don't think that you will find 6x48 screws at Fastenal

I agree that you will not find 6/48 screws at Fastenal. IF you are sure the screws are 6/48 I will send you 4 screws, just tell me how long and give your mailing address.

Larry Miller

Yep..They are 6-48. If you get in a bind, let me know. I can probably come up with some Weaver screws. If you buy new mounts, the screws will come with them.

You want to make certain the screws do not bottom out and not allow the base to be cinched down tightly. After all the screws are in, back all but one out and see if you can wiggle the base. Repeat this will all the screws to make certain one is not hitting bottom.

If you need shims, you can get a packet of sheet brass of various thicknesses at your hobby, hardware or industrial supply store. You can cut them to size with a pair of snips and drill the hole, just a little larger than you need. Once you have this stuff, you can find many uses for it. Brownell probably sell this stuff already cut and drilled, but you will pay ten times the price to avoid two minutes work.

Supposedly there is a Weaver Base that fits Arisaka's - Weaver 48070.
Brownell - 955-010-070 but I can't get Brownell's web site to respond to it.

Also Weaver bases 55 (back) and 46 (front with a 0.065 shim) supposedly
will do it.

The problem at this point is where to buy a 0.065 curved shim ?

I will try Brownell's via Internet Explorer to see if they respond (?)
I use SeaMonkey (Mozilla) Browser.

Mr. Miller and Chargar - thank you for the offers. I think I am onto the proper Weaver
Bases - info from a friend locally.

I may go to Cabella's this afternoon. They don't have all the scope bases behind a counter
where some fool clerk has to look for me !

Damn - I hate to have to rely on some uninterested clerk to determine what I can buy !

DoctorBill

6x40 and 6x48 are the most popular sizes. If you PM me with the length you need I can send you a set of four ratehr than tryig to buy a package of them from Brownells. Most hardware is 6x32 size and a hardware clerk will probably not have what you want. My Weave chart lists #70 bases for front and rear of the Jap rifles.

I just ordered all three Weaver bases from Brownell's.

Weaver 48070 - Brownell - 955-010-070 Arisaka Base - one piece (?)
Brownell - 955-010-046 and 955-010-055

They will come with screws.

I think I am home free ! These should work out fine.

Thank you, gentlemen, for your offers of base screws.

I just bought some 0.5 in wide by 12 inches long K&S Industries Brass strips
at ACE Hardware in the following thicknesses ...0.016" ($1.29), 0.032" ($1.79)
and 0.064" ($2.99). They also had 0.096" thickness.

Shim material for the next ten years. The cost almost broke me, but I persevered !

BTW - Scott at
http://www.theriflescopestore.com/
answered my E-Mail right away and said that the Weaver 49A rear and Weaver 46 front
should fit. Oh well - too late - I already ordered the 46 and 55 bases from Brownell's.
I'll make a shim as I said before.

DoctorBill

Years ago, there were still lots of scopes that didn't have centered reticules floating round. We really had to use brass shims under the mounts to get the reticule anywhere near centered after sighting in. I had a 8X Khales that had crystal clear optics but required a mountain of brass shims.

My gosh I still have an old Bushnell 3x with non centered reticule. Everyone who looks into the rifle says the scope is broke!

I received (from Brownell's) the Weaver # 70 for Arisaka's - the holes drilled by
some unknown person (a previous owner) did not fit.

I also had ordered Weaver #46 (for the front) and Weaver #55 (for the rear).

The latter two fit ! The front needed a shim, but I had two Weaver shims, which
fit when one was ground a tad shorter.

Why do Weaver shims come short with only one hole ? ODD....

Here is the fit with the Bases - I used Permatex Blue Gel Threadblocker on the screws.

http://www.mynetimages.com/5ab9209082.jpg

WalMart had a Tasco Scope for $35 ---- 3-9X 50mm "Bucksight" which
I bought (I am cheap).

Of course it is Chinese...isn't most everything ! ?

http://www.mynetimages.com/bd0de1dc07.jpg

The scope holes were not lined up correctly - the scope obviously points off to the right.

The guy who drilled and tapped this was a "hack' !

The sight adjustment is now fully to the left - dead up against the limit to
bore sight it.

DoctorBill

Since the drilled holes for back Base are offset to the left side from the front base
by about a millimeter, I took the base off and elongated the screw holes off to the
left side with a model maker's rat tail file

http://www.mynetimages.com/8cc5e4ca4a.jpg

and put it back on and slid it to the right a tad, then tightened the screws.

Scope lines up fine now - at least by looking at it.

I will re-boresight the scope tomorrow (it is dark now) to check it out and
then place a small drop of Gorilla Glue under the base to make sure it doesn't
move anymore.

I'll be damned if I am going to go buy some adjustable base for $70 !

It is amazing the little problems one runs into. One has to be "Mr FixIt".

DoctorBill

VERY Useful Information !

I wish I had found this several weeks ago !

Weaver's Scope Mounting Rail Specifications - from Brownell's web site.

http://www.mynetimages.com/0d2062475f.jpg

http://www.mynetimages.com/0d2062475f.jpg

Either copy the picture (Save as...) or go to the link and copy that.

WOW ! Ignorance is very expensive.

"In the absence of light, darkness prevails."

DoctorBill