Receiver casting types.

[Ireload2]

I was not able to post to the sticky thread about the receiver types.
The common shotgun/Topper receiver appears to be a sand casting, liike the process used to make your grannnie's skillet.
Sand casting is not a very precision process but does produce very inexpensive castings. I have no idea what material is used for the Topper type receivers.

The high pressure receiver appears to be an investment casting. This process uses a an aluminum mould in which wax is injected.
The injected wax receiver is coated with multiple coats of ceramic slurry to form a shell. Then the shell is heated and the wax is burned out leaving a cavity. While the ceramic mould is still hot it is filled with molten metal. High strength carbon steels and stainless steels can be cast with this process.

[quickdtoo]

The SB2 frame is indeed an investment cast alloy, what alloy exactly is H&R/Marlin's secret. What they're made of is pretty much a moot point as they're soon to all be made to SB2 specs, the 10ga and 12ga slug gun frames already are. Frame construction has been a controversial topic as to how strong the SB1 frame is compared to the SB2, there's been more than one thread that was locked and one member was banned due to his insistence that SB1 frames are safe for use with low pressure rifle/pistol chamberings. For our purposes, in the interest of safety,  SB1 frame discussions will be limited to production chamberings.

Tim