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Posted: 5/17/2004 8:58:27 AM EDT
| I have seen this topic before but never took the time to read it and now...... I have a question, I am looking into buying a RRA complete upper and in its description it says that it is "Wilson chrome moly (NOT CHROME LINED) barrel". I was wondering what that means? any help would be appreciated. |
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Chrome Moly is referring to the chemical content of AISI 4140 series steel. It normally contains the following: Component Wt. % C 0.38 - 0.43 Cr 0.8 - 1.1 Fe 96.785 - 97.84 Mn 0.7 - 1 Mo 0.15 - 0.25 P Max 0.035 S Max 0.04 Si 0.15 - 0.3 Based on the heat treating process, the material can have a variety of differnet physical properties. This is something that I worked with in the Oil Patch in here in Texas for various oil tools. The Chrome Moly comes from the elements that make up the alloy above. With a good firm the physical properties should be OK. However, they can vary drastically based on the chemistry, heat treatment, and handling during the heat treatment with a low budget firm (iei one without engineering and quality control). A key point is that this is not chrome lined. With any higher carbon steel, it will corrode and will not have the wear characteristics of a a chrome lined barrel. Finally, chrome lining itseld is not a panacea. A bad chrome job is much worse than no chrome job. In the Oil Patch chrome plating for critical service remained an ongoing problem with the best chrome suppliers. If you had good QC, they usually provided a good product 95% of the time. The bottom line is to consider a firm with a solid reputation for quality control and engineering. There is a good reason why some weapons are more costly than others. You are in essence paying for the quality and engineering. Sorry about the long answer but I am still an engineer in manufacturing. This is what I do when I am not hanging out with shooting and bullets. |
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