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The Range
Rifle & Shotgun Discussion
Empirical Evidence for AR Supremacy ???
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<blockquote data-quote="KurtM" data-source="post: 891959" data-attributes="member: 6064"><p>Ahhhhhh a whole different can of Mil Spec worms...why would anyone need to know how many rounds were fire from an M-9....hahahahahaha</p><p></p><p>As for Shot Peening...well lets just say I agree about the crack propagating thing (only due to the crack running into a rounded stress reliever, the shot impact area), but not the "compressive" part. It is a percussive residual, it can only be compression if there is containment...and on this semi-ductile surface we are talking about metal is neither added or subtracted, just moved around so there can't be containment. we are talking about a process that AT BEST only "disrupts" to a depth of .00005, as we are talking about a air hardening heat treated steel. Now this works great for "surface cracks", but does nothing for stress risers created by sharp machining angles and carbon/chromium inclusions in poorly amalgamated material (a "bad pour" in the metallurgy business) so it only deals with surface cracks ( yes they can grow ) and the MPI can't tell you about inclusions...It ain't X Ray.. so we are talking about a superficial treatment and a test that while making one feel good, don't really tell you about your bolt. (These are the exact reasons Reed and John question this process)</p><p></p><p> Now since we are talking about failure, metallurgy, and stress risers of which I have a bit of passing knowledge, and since you seem to have a good grasp on this subject....where do bolts usually fail?, the least common is to shear a locking lug, although it does happen , usually on full auto guns that see lots of mag dumps.. Where is it?</p><p></p><p>For extra credit, What Bolt part fails the most out of all of them...not to include firing pins being cooked by pierced primers? and consumables like gas rings and extractors.</p><p></p><p>BTW Glocktogo the DPMS rifle that Blew up...the only parts that was still usable in the upper were the Bolt Carrier, dust cover, and forward assist, I guess what I am saying is I wouldn't worry about your bolt carrier. Kurt Miller</p></blockquote><p></p>
[QUOTE="KurtM, post: 891959, member: 6064"] Ahhhhhh a whole different can of Mil Spec worms...why would anyone need to know how many rounds were fire from an M-9....hahahahahaha As for Shot Peening...well lets just say I agree about the crack propagating thing (only due to the crack running into a rounded stress reliever, the shot impact area), but not the "compressive" part. It is a percussive residual, it can only be compression if there is containment...and on this semi-ductile surface we are talking about metal is neither added or subtracted, just moved around so there can't be containment. we are talking about a process that AT BEST only "disrupts" to a depth of .00005, as we are talking about a air hardening heat treated steel. Now this works great for "surface cracks", but does nothing for stress risers created by sharp machining angles and carbon/chromium inclusions in poorly amalgamated material (a "bad pour" in the metallurgy business) so it only deals with surface cracks ( yes they can grow ) and the MPI can't tell you about inclusions...It ain't X Ray.. so we are talking about a superficial treatment and a test that while making one feel good, don't really tell you about your bolt. (These are the exact reasons Reed and John question this process) Now since we are talking about failure, metallurgy, and stress risers of which I have a bit of passing knowledge, and since you seem to have a good grasp on this subject....where do bolts usually fail?, the least common is to shear a locking lug, although it does happen , usually on full auto guns that see lots of mag dumps.. Where is it? For extra credit, What Bolt part fails the most out of all of them...not to include firing pins being cooked by pierced primers? and consumables like gas rings and extractors. BTW Glocktogo the DPMS rifle that Blew up...the only parts that was still usable in the upper were the Bolt Carrier, dust cover, and forward assist, I guess what I am saying is I wouldn't worry about your bolt carrier. Kurt Miller [/QUOTE]
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