Lyman 57 screw size?

[RU shooter]

Just got a Lyman 57 sight off a member here( thanks again JAKE) and plan on drill and tapping for it this weekend . I forgot it at home before I left for work today to check what the mounting screw size was so I can borrow the tap from work , I'm thinking 6-32 ??? Anyone know for sure ? It's an older all steel model if it makes a difference for a Springfield .

Tim

[gnoahhh]

6-48 is standard. 6-32 might not stay tight after installation.

[Char-Gar]

Just got a Lyman 57 sight off a member here( thanks again JAKE) and plan on drill and tapping for it this weekend . I forgot it at home before I left for work today to check what the mounting screw size was so I can borrow the tap from work , I'm thinking 6-32 ??? Anyone know for sure ? It's an older all steel model if it makes a difference for a Springfield .

Tim


6-48 is what came from the factory and rifles drilled and tapped for receiver sights were 6-48 also. This size is used by both Lyman and Redfield.

[RU shooter]

Thank you both , looks like I'll be stopping at the hardware store don't have that size at work .

Tim

[gnoahhh]

Lucky you if the hardware store has 6-48's in stock. They aren't used for much outside of gunsmithing and instrument repair. I just order a handful from Brownell's whenever I need some. Perhaps your friendly local gunsmith will lay a couple on you?

[LAGS]

I hope you find the tap you need. but I want to caution you that drilling and tapping the receiver is only Half the battle, and the Easy Part.
Getting the sight to be in alignment is the hard part.
The sight has to be perfectly level and plumb both left to right as well as front to rear.
This can be hard to accomplish with the rounded sides of the receiver on Springfields and Mausers.
Plus, when you try to drill the holes, the bit can walk very easily.
Once the holes are drilled and tapped, there is no going back to make any kind of adjustment.

[claude]

Might be worth your time to check these sites out.

Taps and drills

http://www.castbullet.com/drilltap.htm

Screws

http://www.castbullet.com/screws.htm

[hockeynick39]

Brownell's should have some tap and die sets in stock. Will concur on 6-48.

[W.R.Buchanan]

They are definitely 6-48 screws and taps are not going to be available just anywhere. You will have to go to a large machine shop supplier like MSC or Brownell's for these taps. Figure about $25 each and you'll probably need several. They break pretty easy!

You will also have to break thru the case hardening on the receiver which on a Springfield is 95% of the job.

It definitely needs to be done on a mill as you will be changing bits and such over and over and the only way to keep the hole locations true is by doing it on a mill where you can positively locate the part.

The holes need to be placed on the centerline of the receiver which is defined by the slot on the right side that the extractor runs in. IE: placed in the center of that slot.

Make sure to locate the sight far enough forward so that it clears the bolt handle.

I am a highly skilled machinist toolmaker with 30+ years experience. Drilling and tapping these two holes on my Springfield were easily the hardest two holes I have ever done.

It took me two full hours!

I am only warning you of this because it took every bit of skill I could muster to pull this off.

If you do not possess a similar level of skill (and judging from your OP where you didn't know the thread size it doesn't sound like you do),,, this might be better done by a really good gunsmith.

This is NOT an easy job!!!!!! But it is really easy to make a mess of!!!!

This is not intended to be a personal attack but merely a warning that sometimes one needs assess ones true abilities and FARM the JOB OUT!

words of experience here.

Randy

[Clark]

When I get rifles cheap at the gun show, it is often because someone screwed up the drill and tap and add scope mounts process.
I have drilled and tapped ~ 50 receivers, and only did one that was hard, a Swedish Mauser. But I have never worked on a Springfield.
Usually what goes wrong is holes are drilled in the wrong place.
If you can paint the receiver with di-chem and scribe lines with a height gauge, and then start with a short fat drill in the mill, then the hole might be where it is supposed to be. I have bright lights and wear an Optivisor to try to see what I am doing. Before I work on anything expensive, I consider practicing on scrap.

[Geezer in NH]

Brownell's or MSC get all type to make the order worthwhile Start, Plug and Bottoming

[LAGS]

On oddball receivers or ones that have been Bubba'ed. I crazy glue the receiver sight to the receiver to line it up right.
Then I mark the holes with a drill going thru the receiver sight holes, but only deep enough to leave a centering hole mark with the larger drill.
Pop the receiver sight off, and drill and tap the holes per the centering mark left by the drill bit that fits the receiver sight hole with the proper size screw hole size.

[W.R.Buchanan]

Springfield receivers are case hardened about .015-.020 deep and it is about Rc 63-65. Getting thru the outside is not that big a problem. I used a grinding point in the mill and ran it at 3000 rpms to spot the holes.

A carbide drill wouldn't touch the exterior.

Drilling thru the soft portion is not that bad until you get to the inside then you run into another .015-.020 of case hardening that you can't just grind thru. The drills don't like this either, even nice cobalt stub drills snap like toothpicks when they hook up to a hard edge.

I broke 2 drills (One in each hole) to get thru. Then I broke the same tap 4 separate times before getting the threads all the way thru. Every time I would get to the inside and creep up on the torque the end of the tap would just snap off. Luckily there was only a small portion of the tap in the hole which luckily broke out when hit with a center punch.

Please note this all was done on my milling machine and would have been disastrous if done without a firm hold in a mill vise or by using a drill jig that positively locates the receiver. The tap handle had a center in it to locate it perfectly in line with the hole. Only two fingers were used to turn the handle.

It takes several tries to get the holes drilled and tapped you have to have a mechanical way of locating the holes so that you can get the tools started multiple times in the same position.

Like I said above this is not an easy job. Maybe it is on other receivers but the Springfields are a bear.

I have heard of guys using a torch to heat the spots where the holes are located to soften the case but it seems very iffy to me.

Randy

[Clark]

Randy,
If I am ever having a bad day, I should just read your above post.134295

My father bought his 1931 in 1946 at Sears and Roebuck for $39.95. It was like the one he got his marksmanship badge with in WWII.

We were never temped to drill holes in it. But someone took the sling:(

[W.R.Buchanan]

Clark: the sling is pretty easy. the holes aren't. It was hot that day and I sweated blood over those holes for the full 2 hours!

This barreled action was pristine and the idea of ruining it was right in front of me the whole time.

When I finally mounted the sight and it came out right I went and had a drink!

I have done several other D&T jobs on different guns, several Mausers, several Marlins. They were easy and strait forward. None were remotely as bad as the Springfield.

In fact I have sweated blood over high dollar parts made out of oddball materials in my shop many times. Believe me you don't want to scrap a $2000 part on the last operation. None were as bad as those two holes on that gun.

Here's a pic of the action with the sight on it. By comparison the Timmney Trigger took 15 seconds to install and worked perfectly right out of the box.

Randy

[Clark]

I have not been directly involved, but 20 years ago someone I was building rifles with was building rifles with some other guys, and they had to get an EDM shop to bail them out.
https://www.youtube.com/watch?v=YbeKxFBZrF8

Last month I got an 1885 Win 45/70 and an 1873 44-40 from the great great grandson of the original owner still on the original homestead. Two pre 1899 antiques for $1500. But I had to send cash to someone who would give it to someone who would give it to someone, and then maybe the rifles would work their way back to me. I have never met ANY of these people. But the rifles showed up. After I missed sleep.

This week I bought a Bridgeport mill off ebay from LA that was local pick up only. I was thinking about buying a trailer and driving for 5 days. I managed to find a packing company, shipping, insurance, forklift, ... all with the phone and email.
After I missed sleep.
But the mill was easier, because I could say to myself, "What am I worrying about? At least I did not break off a tap in a rifle receiver."