Thanks, lots of great info. The boys sure do have their favorites. Colts were nice in the service, DPMS that I have does function and feed nicely. I dont have to use it to defend my life so far the prarie dogs dont shoot back.
Quote:
7- Magnetic Particle Inspected (MPI)
Magnetic Particle testing is a military designated test that is part of the TDP (Technical Data Package.) Colt has made such a ruckus about this procedure, that I hear more about MP tested barrels and bolts than any other argument for Colt. Well, others now offer this as well, and I have YET to EVER hear about a barrel or bolt that failed this test. Maybe it happens, but I've just never heard of it.
From Sgt Geezer:
Any magnetic metal object is placed between two jaws (aligned so that the grain of the steel is between) and electrically charged with pulses. Object has liquid solution containing particles that fluoresce under blacklight or magnetic dry powder is used.
Any non metallic occlusion or "crack" will cause the collection of these particles at these indications. In new manufacture it assures the "steel" or melt is good without any contaminants.
Shotpeening is...a process that uses lead....glass... or / usually steel shot through a "airgun" or blasting device that peens the surface metal over and creates hardness and crack resistance.
I chalk these procceses up to "voodoo," but someone MIGHT correct me on this. (Thanks Sgt Geezer!)
That finishes up the barrel portion, so now let's move on to the REST of the rifle! "
He may know the firearm but he doesn't know jack about NDI/E
That MPI sounds just like the old Magnaflux process, and that works for cracks, cold shuts, and a lot of other things it is intended for, but it can only detect these mechanical flaws, not metalurgical ones.
Shot peening [properly done] does increase "crack resistance" [poor choice of words] fatigue resistance more properly, by leaving a residual compressive straign on the surface of the part.
It does sound like that guy needs to check up on His technical details.
I found the MPI section a bit amusing as well
I had to de-mag all the bolt carriers on my four Busmasters.
My DPMS stick runs really good and I haven't had any problems with it except for that you can't get the dam gas block off without stripping one of the hex bolts. I had to drill the dam thing out.
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