Drills and taps for hardened receiver


PDA






Sun Tzu warrior
January 10, 2013, 09:04 PM
I am wanting to mount a Pachmayer Lo-Swing scope mount on a SS hardened receiver. Does anyone know a good source for carbide drills and taps?
Thanks in advance!

If you enjoyed reading about "Drills and taps for hardened receiver" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!
rcmodel
January 10, 2013, 09:08 PM
Brownell's sells Carbide drills.

I don't know of anyone selling carbide taps, because they would break way too easy.

I seriously doubt your stainless receiver is as hard as you think it is either.

Receivers are typically not hardened super hard because that would make them so brittle they would shatter when fired.

Exactly what kind of rifle is it?

rc

4v50 Gary
January 10, 2013, 09:11 PM
High speed steel. Break off a carbide tool and it's tough to remove.

Sun Tzu warrior
January 10, 2013, 09:29 PM
It is an early Mini 14, Has the "R" with a circle around it. Have drilled one hole (had to use carbide), and a tap wouldn't touch it.

Jim K
January 10, 2013, 09:31 PM
Spot anneal it.

Jim

rcmodel
January 10, 2013, 09:34 PM
Well, Burning through it with a carbide drill may actually be making it harder on the surface of the hole.

I don't know what to tell you now, other then get some Premium hi-speed taps and Do-Drill oil from Brownell's and try it again.

http://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/taps-dies/taps/perfect-cut-premium-tap-prod9963.aspx

http://www.brownells.com/gunsmith-tools-supplies/general-gunsmith-tools/taps-dies/tapping-cutting-fluids/universal-do-drill-prod1120.aspx

rc

Sun Tzu warrior
January 10, 2013, 09:48 PM
Thanks guys! I wouldn't want to change the integrety of the receiver by heating it.
The "R" with the circle, indicates Rugers initial problem with the heat treating of receivers, was corrected on this perticular weapon, wouldn't want to revisit that problem.
Guess I'll just quit while I'm behind. I will just fill that one small hole with a ductile iron plug.

1911Tuner
January 10, 2013, 09:53 PM
How hard is it? Rule of thumb...If you can file it, you can drill it.

Kp321
January 10, 2013, 10:04 PM
I drilled and tapped one of those early SS Mini-14's several years ago. My advice is to use a no-drill mount. I finally got the job done with a carbide drill and new hi-speed tap for each hole.

Sun Tzu warrior
January 10, 2013, 10:05 PM
I can drill it, with a carbide drill bit, the tap however wont touch it. The tap is high quality from a mill supply, the bit is correct size for the tap. Can't get the tap to even start. I admit.... I'm chicken! Glad I tried to tap before drilling the other 3 holes!

Jim K
January 11, 2013, 03:16 PM
Spot annealing shouldn't affect the heat treatment of the receiver. It uses a tiny flame to heat a spot about 1/4". Some folks say an electric soldering iron will do the job, but IMHO those won't get hot enough.

Jim

4v50 Gary
January 11, 2013, 06:45 PM
BTW, I don't recommend scoping a Mini-14. The shell ejector shoots the empty case straight up and into the scope base or if a two piece scope base, into the scope body. Eventually the scope will break.

That's why Ruger developed the Ranch. It has side ejection and a buffer to dampen the recoil.

ApacheCoTodd
January 12, 2013, 03:13 PM
Are you trying "spiral point" taps for the initial cutting?

Also for me:

When not available
AND
When unaffected by the lessening of the first couple threads
I've bevelled and/or over-drilled an appropriate depth to allow the engagement of an otherwise problematic tap. Of course a fella's got to have sufficient engagement on the available full meat threads further down the hole.

jmorris
January 12, 2013, 04:19 PM
Carbide taps are common in the industry. Google "carbide tap"

jmorris
January 12, 2013, 04:30 PM
This one was done with both a carbide "drill" it actually burnishes the hole then a forming tap makes the threads.

jmorris
January 12, 2013, 04:33 PM
It is for forming high pressure NPT threads in SS. The "drill" pushes extra material down inside the pipe to allow for good seal.

Not really what your asking about but the only example I have at arms length.

jmorris
January 12, 2013, 04:34 PM
Saves a lot of time and money vs welding and x-ray tests.

Miked7762
January 12, 2013, 07:11 PM
It won't cut because you are literally forge welding the tap to the receiver. The tap displaces the chromium oxide layer and as it reforms due to oxygen exposure it traps the tap. You need an appropriate cutting oil that is high in sulfur content. It will prevent the oxide layer from reforming until the tap is removed.

ApacheCoTodd
January 12, 2013, 07:35 PM
It won't cut because you are literally forge welding the tap to the receiver. The tap displaces the chromium oxide layer and as it reforms due to oxygen exposure it traps the tap. You need an appropriate cutting oil that is high in sulfur content. It will prevent the oxide layer from reforming until the tap is removed.
Boy now there's a tip I missed. In addition to what I posted above, another factor in my past successes has been the use of Rapid-Tap. I bought a distributor out of it when it got outlawed in California and am still using up my copious reserves to this day.

The difference showed immediately in the tool's life extension when we were using it to work ATS-34 before and after heat-treat. Fast, cool happy cutting with over a three-fold extension in tool life. Sweet!

Sun Tzu warrior
January 22, 2013, 11:41 PM
Thanks everyone for the advice! My "Spidy senses" are telling me to leave well enough alone.

docsleepy
January 23, 2013, 12:21 AM
I'm not an expert on receivers and hardness but surely the receiver will hold together without the ENTIRE THING being harder than a file!!!

I don't think steel anneals unless you exceed the critical temperature. If you have already created the hole, it should be much eaiser to use a very small oxyacetylene tip and heat the surface metal on the inside of the hole to just red hot (in a dark room) and allow to cool slowly. This might reduce the hardness enough to allow tapping.

Of course, my willingness to try this would vary depending on the cost of the receiver involved.

Clark
January 23, 2013, 11:18 AM
I have drilled holes in annealed 4140 and the tool got hot and then got hot or the tool got hot and then got dull. At any rate, it made a spot that I can't drill with high speed steel or Cobalt. So I have to order a carbide drill. I hate it when that happens. So I flood the drill with coolant when going through tool steel.

I would not have guessed it, but it looks like the mini 14 stainless receivers ARE hardened.


RUGER
MODEL STAINLESS STEEL MINI-14 RIFLES
RECALL: Ruger is recalling all stainless steel Mini-14 rifles with serial numbers below 182-51929 with only one proofmark on the receiver.
We have examined a total of three stainless steel Mini-14 rifles that have been returned from users with cracked receivers. In every instance, this situation was traced to a combination of two factors:
The receivers exhibited excessive hardness; and

The rifles were fired either with an obstruction in the bore or with faulty ammunition creating extremely excessive pressures.
Not all stainless steel Mini-14 rifles have an excessively hard receiver. Every Mini-14 ever shipped, like other Ruger firearms, has been proof tested. We cannot tell which ones are too hard by serial number alone. Therefore, we are recalling all of our stainless steel Mini-14 rifles below serial number 182-51929 bearing only one proofmark on the receiver for inspection, testing, and re-heat treatment, if necessary. Most rifles will require only a Rockwell test and will be returned after testing. Rifles tested will be given an additional proofmark. Only some rifles will require re-heat treatment.

Remove the buttstock from your rifle, and remove all custom accessories. The remainder of the rifle is all that we need. Securely package and insure your barreled action, bolt, trigger housing group, and handguard (a shipping carton is available upon request), and ship it UPS AOD to:

Sturm, Ruger & Co., Inc.
Guild Road - Dept. 14
Newport, New Hampshire 03773
(603) 863-3300 ext. Mini-14

Source:
Company Notice 1981
AFTE Journal, July 1981; Volume 13, Number 3:6
American Rifleman, November 1981; page 66

Sun Tzu warrior
January 23, 2013, 10:25 PM
This perticular rifle has a serial number above the re-call, and one proof mark. So apperantly, although not "Excessively hardened" still hardened never the less.
I was aware of the re-call and also that this one was not included. Thanks Clark, I don't think some belived that this receiver was hardened. Again, thanks guys for the input, but I am still shelving the project, due to consideration of "the cost of the receiver involved".
As Docsleepy stated.

rodinal220
January 25, 2013, 10:56 AM
http://www.use-enco.com/CGI/INSRHM

http://kbctools.com/usa/main.cfm

http://www1.mscdirect.com/cgi/nnsrhm

If you enjoyed reading about "Drills and taps for hardened receiver" here in TheHighRoad.org archive, you'll LOVE our community. Come join TheHighRoad.org today for the full version!