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Trunnion Survey - Further Analysis

I started a thread on Calguns that began as my rant on how little data we have for just how and why trunnions crack. We agreed on the thread to conduct a survey of trunnions for more empirical data. So far we have one committed for a cracked trunnion to analyze. I will supply three uncracked trunnions, consisting of two surplus and one RCM virgin trunnion.

The main thread will be located on Military Firearm with summaries posted here on HKPro.
Trunnion Survey - Further Analysis

Does anyone have a cracked trunnion, soft, dinged up JLD or other defective trunnion you've been hanging on to that you could commit to the survey that you wouldn't feel too badly about seeing completely destroyed? If so, please contact me. Holescreek and Chasgee have offered to perform the analysis between them. In brief, the survey will cover the following:

* Dimensional analysis through scanning of each trunnion to build a contrace, overlaying each trunnion to compare ramp angles and other dimensions. The cross pin holes, so often cited as the source of the problem, will be part of what is captured

* Initial surface hardness testing to determine consistency of hardness throughout the part and what that hardness actually is

* Magnified high res images of the part, especially useful for documenting the cracked trunnions supplied by two participants

* Microhardness testing through sectioning (destructive testing) to learn if trunnions are in fact through-hardened or some other process is used and what the average hardness is for each from surface to core and across specific structures

* Chemical analysis to determine alloy for comparison across multiple sources of trunnions

The study was completed a few weeks ago. You can find the results here: Study Pics/
Trunnion Survey - Further Analysis

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