Cryo treatment? Is AAC ever planning on selling BCG parts?
Jeremy
Printable View
Yes - probably every tool steel company.
As far as I can tell, no.
They seem to use S7 when they cannot get S2. Likewise, companies that are too small to get C158 tend to substitute 9310. While I know S7 is not as good, it is not bad. And while I don't think 9310 is as good, it is not bad. Not chopped liver by any means.
Does it bother anybody that the bolt design requires for some rather exotic materials to be used?
Is this smart engineering / material selection for a very optimized design or material fixes for a marginal design?
C158 bolt (proprietary / strategic)
S2 extractor pin (proprietary)
A2 extractor (common and reasonable choice)
I had always assumed that an outfit with access to aerospace materials would use the toughest, most durable (at the time) materials.
Part of the demensional design of the parts, was dictated by some of the overall goals related to why the weapon was designed. Such as weight and size requirements. The exotic materials allowed them to design smaller parts that had similar durability to a larger assembly made out of lesser materials.
One of the other variables that dictated some of the design choices was manufacturing capability. This likely played a role with bolt lug design, and why companies like KAC are able to make stronger bolts that fit in roughly the same space. Machining was more difficult and time consuming back when the AR15 was designed. Along with it being more difficult to manufacture parts with smooth radius' (radi?) with exacting tolerances.
While manufacturing technology has advanced since that time, I would be suprised if there aren't steels available today that could be substituted for these parts, and be stronger/more able to cope with the loads, than the steels originally chosen for the parts. I mean surely metalurgy has advanced since the 50's
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I've asked this question several times and have never received a satidfactory answer. I am pretty certain Eugene Stoner didn't have the metals that are currently in the TDP when he designed the AR(s) in the 50's. The TDP has evolved over the last half century.
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I can't speak to the material history of extractor (the marginal information is quite blurry) or the extractor pin (no print on hand) but my bolt print which is a 27APR70 ARDC, redrawn from Colt's J61538 Rev. E w/C, has as its Revision B a change to (1), which is the material call in the marginal information, dated 01SEP70, the note "See EO HRD 02197-3". So, as far back as APR70, the print specified C158. The date of the last revision is 80-02-13.
The extractor print calls 4140 or 4340 gun quality on this extractor print but the last visible Revision date on it is 06OCT70 and the latest is a blurry 87-02-1?