Old AR15 Parts of Unknown Origin

Over the years I’ve accumulated a small number of AR parts of unknown origin. During the AWB I sourced a couple Bushmaster rifles. Later changed some parts like triggers to geissles.

At some point I bought some LWRC parts kits and put some of those in some guns.

Now I just got a few more Lower Parts Kits from a decent brand, as part of a package deal with BCGs and I don’t need them but realizd I should separate them out and label them so I know the origin. Previously I’d take any spare like-parts and sort together. All GI triggers/hammers together, regardless of origin for example.

I don’t strictly need any of these unknown origin parts currently but they don’t take up much space, so I may quarantine them, label them unknown and keep for a rainy day if no alternatives exist.

I am interested in learning more about metrology and gunsmithing so I’m wondering if I can put in some effort to ID the quality of the parts. Such as what kind of steel it is, if it’s in spec based on measurements down to 1/100 or 1/1000 of an inch. Of course, the labor effort involved would make more sense to throw them away and spend $100 or $200 on a few BCM LPKs but the purpose would be to gain some knowledge.

Anyone have opinions on what they do with spare parts of unknown origin and specifically for my case, what is recommended I do with them? Any references on finding the exact parts specs for me to practice metrology?

I shit can unknown parts. I have a large supply of known quality spare parts. I refuse to have any unknown components. All my AR's have a pedigree, a log sheet and a build sheet. My philosophy is that if the shit hits the fan that I can grab any one of my AR's and it is built to a hard use standard. Generally they are only used as range/ training/ competition guns, but I build them my way. Even if I buy a complete gun, or lower or upper, it gets its own log and build sheet for any modifications and what it is etc. For instance:

BCM 365 complete lower. Trigger G SSA. FCD bolt catch V3. Grip dremeled. MP SL-S stock.

If I build a stripped lower:

LMT 282 Stripped lower. SOLGW LPK, Trigger G SSA. FCD bolt catch V2. Dremeled bcm grip and trigger guard. MP SL-S stock. Sionics RE, Spring and H buffer.

I do the same for uppers etc. Then any further mods are logged and added to the build sheet.

Cheers, Steve