02-23-2013, 07:50 PM
For reliability and QC procedures, Colt small parts are at the top, but not sold in kits that I've seen.
I would rate the Daniel Defense LPK's as one of the top kits on the market.
Keep in mind that these small parts are made by specialty niche sections of the industry, where one only does springs and maybe roll pins, while another does Metal Injection Molding (MIM)for magazine catches, bolt catches, hammers and triggers, and another does case-hardening. Another will do detents, pins, and plungers, with another doing selectors and disconnectors.
The plastic, glass nylon, zytel, and such are an entirely different market segment.
With the Rock River-branded parts, they have good triggers, hammers, and other components, except for the detents, which are sourced from a corner-cutting practice in the AR15 industry that saves money by zinc-plating them, rather than cadmium-plating like the Mil-spec Technical Data Package calls for. I learned the hard way that lower parts are nowhere near the same when running high-volume courses in extreme cold weather, and my pistol grip fragmented, exposing zinc-plated detents that were corroding in real-time before my eyes, as in chemical reactions visibly reacting on the selector detent surface.
None of the companies packaging the parts together are the manufacturers, due to the depth and width of manufacturing capacity that would be required to support such an operation, so like with AR15's, brand names mean the final assembly warehouse.
There are also a lot of parts being imported from the Philippines for the AR15, to include bolt carriers, barrel extensions, upper receivers (with no forge code), all the lower parts, etc.
If you want to get an education in lower parts kits, break down a Colt SP-1, Sporter II, 6920, and then any modern vismod AR15 and compare them. The differences are quite pronounced, starting with the fact that the components from a Colt have proof and QC inspection stamps on them, and there are dimensional and design differences as well.
I would rate the Daniel Defense LPK's as one of the top kits on the market.
Keep in mind that these small parts are made by specialty niche sections of the industry, where one only does springs and maybe roll pins, while another does Metal Injection Molding (MIM)for magazine catches, bolt catches, hammers and triggers, and another does case-hardening. Another will do detents, pins, and plungers, with another doing selectors and disconnectors.
The plastic, glass nylon, zytel, and such are an entirely different market segment.
With the Rock River-branded parts, they have good triggers, hammers, and other components, except for the detents, which are sourced from a corner-cutting practice in the AR15 industry that saves money by zinc-plating them, rather than cadmium-plating like the Mil-spec Technical Data Package calls for. I learned the hard way that lower parts are nowhere near the same when running high-volume courses in extreme cold weather, and my pistol grip fragmented, exposing zinc-plated detents that were corroding in real-time before my eyes, as in chemical reactions visibly reacting on the selector detent surface.
None of the companies packaging the parts together are the manufacturers, due to the depth and width of manufacturing capacity that would be required to support such an operation, so like with AR15's, brand names mean the final assembly warehouse.
There are also a lot of parts being imported from the Philippines for the AR15, to include bolt carriers, barrel extensions, upper receivers (with no forge code), all the lower parts, etc.
If you want to get an education in lower parts kits, break down a Colt SP-1, Sporter II, 6920, and then any modern vismod AR15 and compare them. The differences are quite pronounced, starting with the fact that the components from a Colt have proof and QC inspection stamps on them, and there are dimensional and design differences as well.