LPK Metallurgy

[prepare]

Investment cast, solid bar stock, billet.

Which mil-spec LPK components are solid bar stock and which components are investment cast and why?

To my knowledge the magazine button is aluminum. 6061 or 7075?

Are any components billet?

Keep it technical please.

[prepare]

Listened to this over a couple of commutes. These guys really get into the minutia.
The majority of the larger LPK parts are investment cast. If you really want to get into the weeds on small parts they also discuss pins and springs, types of steel and coatings.
The take-a-way is materials and processes matter. Buying reputable brands is the smart thing to do because there is commercial stuff out there thats doesn't hold up. I recall a widely known brand that had mim bolt catch's in their LPK's that would fall apart.

[Pappabear]

Prepare, I enjoyed the big shout out to Will Larsen “IraqGunz”. That is one long video that I didn’t have 4 hrs to watch, but jumped around and it had some interesting info.

PB

[prepare]

Gunz was a huge loss that left a big hole here.

[lysander]

Trigger, hammer, safety - precision cast

Magazine catch plate - steel bar stock, or MIM (yep, according to the mil-dwgs)
Bolt catch - precision casting or MIM

Magazine catch shaft, takedown pin, pivot pin, buffer retainer - turned from bar

Magazine catch button, trigger guard - extrusion (7075-T6)

Disconnect - stamped steel

Why? Cost.

Springs - cold formed wire (heat treated after forming)

The following part can also be MIM according to the drawings:
Rear sight base
Rear sight
Front sight post
Ejection port cover latch housing

[m1a_scoutguy]

Here is an all USA-made LPK with NO MIM parts according to the website. Take it for whats it's worth I guess. I have used a few in the last year & while I have not run them hard, torture tested or any other crazy mud/snow/water tests they have performed fine. All installed perfectly in a couple of SOLGW lowers and a few others. So far so good.
https://whitelabelarmory.com/product...+LPKs+and+Kits

[Leuthas]

Gunz was a huge loss that left a big hole here.

Wait what?

EDIT*Nevermind. Found it myself.

[GH41]

In the end it makes little difference what material or process a part is made from or by if it is done correctly and QC takes a look at it. BCM's claim to fame is inspecting every part. Very few others do. Do you guys really think everyone who sells parts has a contractor who manufactures them exclusively for them?

[lysander]

8620 - trigger, safety, bolt catch, pivot pin, take down pin,

8620 - magazine catch plate (MIM)

4620 or 8620 - hammer

4130, 4140, 4340 - buffer retainer

1065, 1070 - disconnect

1018 - magazine catch plate (bar), magazine catch shaft, detents

303 stainless - trigger guard plunger

One thing I find interesting about the M16/AR design is how 'traditional' it really is, as far as construction methods go. The number of metal stampings is very few, less than half a dozen. And, only five major parts are aluminum.

[prepare]

8620 - trigger, safety, bolt catch, pivot pin, take down pin,

8620 - magazine catch plate (MIM)

4620 or 8620 - hammer

4130, 4140, 4340 - buffer retainer

1065, 1070 - disconnect

1018 - magazine catch plate (bar), magazine catch shaft, detents

303 stainless - trigger guard plunger

One thing I find interesting about the M16/AR design is how 'traditional' it really is, as far as construction methods go. The number of metal stampings is very few, less than half a dozen. And, only five major parts are aluminum.

I wonder if that is due to the designers influence in aviation?