AR15 Commercial Comparison Chart .....different manufacturers
- Thread starter SCULLY
- Start date
At least a couple of errors in that listing...
The COLT LE6920's have MIL-SPEC lower receiver pins (the civilian AR6920's don't).
The LMT's have taper pins on the FSB and "H" Buffers are an available option.
All in all an excellent comparison chart.
Mark
The COLT LE6920's have MIL-SPEC lower receiver pins (the civilian AR6920's don't).
The LMT's have taper pins on the FSB and "H" Buffers are an available option.
All in all an excellent comparison chart.
Mark
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P0WERWAGON
CGN Ultra frequent flyer
- Location
- burnaby BC كافر
Stag Model 1, is that Stag arms and Model1Sales?
sad how Olympic arms scored higher than DPMS
sad how Olympic arms scored higher than DPMS
I have two LE6920's (brand new latest production) sitting here right now that both have MIL-SPEC lower Take-Down pins. Just to prove it to myself before I made the posting I took the COLT upper off and mounted a 7" RRA upper and the fit was perfect.
With respect to the LMT uppers, I can't say that I've taken the FSB off and measured them, but LMT insists that they use Taper Pins and they only sell Taper Pins in their parts list (they don't even list straight pins) so that's what I based my statement on. I guess I'll have to pull one apart to verify it one of these days
Mark
The list is not referring to the take down pins which are of course mil-spec, they are speaking to the hammer and trigger pins which are a larger diameter. We have worked on several LMT guns when I was with Hunters, all purchased from Questar and none had taper pins, not that it is a real issue the LMT guns kick ass as is.
Brain Fart
You're right I wasn't even thinking about the trigger and hammer pins (which are larger) I just thought about the take-down and pivot pins which on many Colt's are also not Mil-Spec and require Offset Pins and Offset Bushings if you want to mate the upper and/or lower to anything but another "oversized" Colt.That's what happens when you get old... the mind is the first thing to go... or is it memory... or is it... damn now I can't remember
Magnetic Particle Inspection
How does it work?
Magnetic particle inspection (MPI) is used for the detection of surface and near-surface flaws in ferromagnetic materials. A magnetic field is applied to the specimen, either locally or overall, using a permanent magnet, electromagnet, flexible cables or hand-held prods. If the material is sound, most of the magnetic flux is concentrated below the material's surface. However, if a flaw is present, such that it interacts with the magnetic field, the flux is distorted locally and 'leaks' from the surface of the specimen in the region of the flaw. Fine magnetic particles, applied to the surface of the specimen, are attracted to the area of flux leakage, creating a visible indication of the flaw. The materials commonly used for this purpose are black iron particles and red or yellow iron oxides. In some cases, the iron particles are coated with a fluorescent material enabling them to be viewed under a UV lamp in darkened conditions.
Magnetic particles are usually applied as a suspension in water or paraffin. This enables the particles to flow over the surface and to migrate to any flaws. On hot surfaces, or where contamination is a concern, dry powders may be used as an alternative to wet inks. On dark surfaces, a thin layer of white paint is usually applied, to increase the contrast between the background and the black magnetic particles. The most sensitive technique, however, is to use fluorescent particles viewed under UV (black) light.
MPI is particularly sensitive to surface-breaking or near-surface cracks, even if the crack opening is very narrow. However, if the crack runs parallel to the magnetic field, there is little disturbance to the magnetic field and it is unlikely that the crack will be detected. For this reason it is recommended that the inspection surface is magnetised in two directions at 90° to each other. Alternatively, techniques using swinging or rotating magnetic fields can be used to ensure that all orientations of crack are detectable.
The method of magnetisation depends on the geometry of the component and whether or not all or only part of the specimen is to be magnetised. Permanent magnets are attractive for on-site inspection, as they do not need a power supply. However, they tend only to be used to examine relatively small areas and have to be pulled from the test surface. Despite needing their own power supply, electromagnets (yokes) find widespread application. Their main attraction is that they are easy to remove (once the current has been switched off) and that the strength of the magnetic field can be varied. For example, an AC electromagnet can be used to concentrate the field at the surface where it is needed. Hand-held electrical prods are useful in confined spaces. However, they suffer two major disadvantages that can rule out their use altogether. Firstly, arc strikes can occur at the prod contact points and these can damage the specimen surface. Secondly, because the particles must be applied when the current is on, the inspection becomes a two-man operation. Bench units are fixed installations used to test large numbers of manufactured specimens of various sizes. The electrical components of a mobile unit (as described above) are incorporated in the bench unit making testing more rapid, convenient and efficient.
In some cases, MPI can leave residual fields which subsequently interfere with welding repairs. These can be removed by slowly wiping the surface with an energised AC yoke.
What will it find?
MPI is used to detect surface-breaking and near-surface flaws in ferromagnetic materials. It cannot, however, be used to detect deeply embedded flaws, nor can it be used on non-ferromagnetic materials, such as aluminium, copper or austenitic stainless steel.
RevolverRodger
CGN Ultra frequent flyer
- Location
- Somewhere in QC
Well that comparison chart was just geared toward making the colt look good...
I think the millions of dollars on destructive testing and QC already make Colt look pretty good...though I just built a gun using a DPMS A1e3 upper and Oly lower and all looks good so far, of course I used a Colt barrel, bolt and fire control but it still counts...right
Nothing geared at all, just factual info, if you have some real facts showing the chart is wrong, join M4C and show your info and rob_s will change the chart. Alot of work went into that chart searching out facts, the work is from rob_s and some of the crew at M4C. The chart is not to show info one way or the other, just facts from some of the manufacturers. Use the info as you like.
Taken from M4C...
As you can see, the feed ramps on the regular rifle barrel are cut just to the edge of the barrel extension... but do not extend beyond that edge; while the M4 ramps continue slightly "outside" of the barrel extension.
What this pic doesnt show is the "Receiver" ......As stated, the rest of a properly cut M4 feedramp is in the upper receiver... while the cut in the receiver is small, it matches up with the cut in the barrel extension and makes for a smooth, continuous ramp. Hope this helps a little.
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Extra things they miss:
Anodization, and proper material and hardness of fire control parts.
In addition, just becasue the extractor spring insert is black, it doesn 't mean it is the same material used for the government purchase.
I was also told by Stag factory that their bolts are MPIed, but not subjecteded to HPT by proof rounds. They will only do so by request.
I won't be surprised if Armalite put in the M4 feedramp....RRA did too, well kinda, with a dremel after anodization. LOL.
BTW, all my LMT uppers have straight pins
Anodization, and proper material and hardness of fire control parts.
In addition, just becasue the extractor spring insert is black, it doesn 't mean it is the same material used for the government purchase.
I was also told by Stag factory that their bolts are MPIed, but not subjecteded to HPT by proof rounds. They will only do so by request.
I won't be surprised if Armalite put in the M4 feedramp....RRA did too, well kinda, with a dremel after anodization. LOL.
BTW, all my LMT uppers have straight pins
Thanks for the reference pics, Just checked my Armalite M15A4 Midlength carbine (its apparently new production shipped from armalite to wolverine around Februaryish) and it has the M4 feed ramp cuts in the barrel to the reciever.
Im not so sure about my older LEM15A2 though havent got the upper here.
Im not so sure about my older LEM15A2 though havent got the upper here.
