Repro frame alloy?

[Chuck Heald]

Was the Reproduction frame alloy ever revealed?

[Grantham Forester]

If so, since 1948, all the Japanese steel mills use the electric melt furnace process, same as Allegheny Ludlum, Crucibe and Carpenter Technology use here in America. Best way to produce quality alloyed and tool steels. My employer in the tool and die business is not hesitant to use Japanese steels, but the founder, Dick Beecher, was strictly a Carpenter steel man- T-K was a shop standard in his day.:bowdown:

[Dave Suponski]

Chuck, I seem to remember reading somewhere that 8620 HT was used.

[Chuck Heald]

Dave,
I was hoping Richard Skeuse would know for sure. I know the custom rifle guys like the 8620 because it has a high enough carbon content to core harden to a perfect hardness when it is casehardened. This leaves a super hard case and a strong core, like 2 - 2 1/2 times the tensile strength of low carbon steel if I recall.

But the Repro looks like it was never case hardened. So, I was suspicious it was a 4xxx steel that was martensitically (thru) hardened.

[Grantham Forester]

A friend has a Parker 20 gauge Repro- sweet handling gun, but after two seasons in the grouse coverts, the case coloring is almost worn off the receiver. Were these later production Parkers case colored in a different manner than those made in Meridian Conn.??

[Chuck Heald]

Grant,
I believe the answer is yes. The coloring you see on the Repro's appears to be chemical colors, possible applied with a mix of chemicals and low heat. I really don't know the method, but it doesn't appear to be carbon infused by pack method or cyanide method. Nitriding would produce similar results to pack case hardening methods, but can be essentially colorless.

[edgarspencer]

like 2 - 2 1/2 times the tensile strength of low carbon steel if I recall.

not 2-2 1/2 times.
Plain carbon steel (1010) will have a tensile strength, when normalized and tempered, in the 65-70K range, yield in the 35-40K range. Typical 1018 (Approximates WCB will be 70-36.
8620 (.20C, Ni Cr Mo) will be in the 90K tensile, 60K yield range. 8635 (.35C) will be minimum 105K Tensile, 85K yield.

[Chuck Heald]

Edgar,
When the casehardening process of heating and quenching is done, 8620 will core harden. I can't recall the reference I found on this at the moment. The core came up to about twice the strength of normalized.

[edgarspencer]

Any carbon steel will have a higher hardness (Brinell), and, logically, UTS will be higher, when quenched and tempered than when Normalized and tempered, however ductility will suffer dramatically. Quenching will give you a higher surface, or near surface hardness, but the core will be less so. Air quenching after normalizing will give a more uniform cross sectional hardness.

[Linn Matthews]

Edgar
Thanks for your note. Would you please comment re your thoughts of what treatments would produce the best receiver?
Thank you

Linn

[Rex Northen]

Great information here - thanks for sharing!

[Chuck Heald]

Edgar
Thanks for your note. Would you please comment re your thoughts of what treatments would produce the best receiver?
Thank you

Linn

In modern guns, the receivers are often made of 4140 hardened and tempered to mid 30's Rockwell C scale.

The RBL is an example of a 4140 frame. On my visit to the CSM plant, Tony told me that they pre-hardened/tempered the frame blanks prior to machining. This did two things for them.

First it reduced the grain size of the steel and allowed for finer finish of the machined surfaces. Normalized 4140 machines poorly and leaves a rough finish. Slightly hardened, it machines with fine finish, albeit it takes a bit more energy to cut.

When a part will never be welded, 4130 and 4140 can have a small amount of lead added as an alloy to facilitate better machinability. This addition doesn't affect mechanical properties much from a practical standpoint. However, the RBL has a welded on upper tang.
http://i26.photobucket.com/albums/c125/roaniecowpony/firstopofrcvrs.jpg

Second, it eliminated distortion from heat treat after machining.

[Dave Suponski]

I believe the same holds true for 200 series Stainless Steel. I remember machining 203EZ Stainless and it left great finishes. There are also some leaded low carbon steels that machine great but I can't remember the series. Chuck you might be right about 4140 for the Repros. But it does machine lousy.

[Chuck Heald]

Dave
I've made some parts from leaded mild steels in the past.

This is a triggerguard and floorplate on a custom Rem 600. I whittled it from a solid block of 12L14. and hand filed the curvy stuff. The stuff machined about like aluminum.

http://i26.photobucket.com/albums/c125/roaniecowpony/PICT0161.jpg

[edgarspencer]

Great looking trigger guard!
Finding any alloy steels with either lead or selenium today is nighon impossible. I used to produce a 303 stainless, but just having selenium on hand was a liability.
Did you ever notice how the higher grades differ in case colors from the lower grades. I have always believed that the engravers, whether in-house, or contract, refused work on the more hardened actions based on the time and graver tool wear. The frames, naturally were always the same base material, but the secondary heat treatments given must have been either annealed or drawn back to allow the engraver something softer to work with.
It doesn't surprise me that Galazan uses 4140. It would most certainly be the billet of choice for strength and ductility.
I regret not having more interest in the materials used by the old-time makers, as I had both an optical emission, and xray fluorescent spectrometer in my lab, not to mention the ability to photo-micrograph materials to see their grain structure. Hardness testing wood have involved leaving a tiny braille mark, but I could have done it in an engraved aread and the teeny dot would have blended right in. Maybe in my next life.

[Dave Suponski]

Edgar, Thank you for your input. I always learn from it......:bowdown:

[Chuck Heald]

Edgar,
We had a guy on the doublegunshop board 4-5 yrs back that was the manager over the lab at a metals outfit, I think up in Oregon (Ti was their specialty), that wanted to do a bunch of testing of samples from barrels of doubles. I made the tensile (hoop) test fixture. Many members contributed samples. Shortly after I sent the fixture to him, he fell off the radar. Woulda been fascinating to have seen the metallurgical and mechanical data.

[Chuck Heald]

Looking at that picture of me holding that RBL frame makes me think that may be steel extrusion.

[Dave Suponski]

Chuck, I sent that gentleman several samples of different types of Parker barrel steels. I have his contact info but he has never replied to my emails.

[Chuck Heald]

Makes me think something bad happened. A couple of us were in daily contact with him until ... nothing.