AR fire control group steel type?

[MattyB]

I asked in another forum and havent recieved an answer but I was talking with a friend at the range about our rifles and he asked what the metal our FCG parts are made out of.

I didnt and still dont know but figured it was a case hardened chromoly steel like 4130.

Curious if anyone knows what the trigger, hammer and disconnector are made out of.

[kcstott]

FWIW 4130 is a through hardening steel not a case hardening steel.

My best guess is a cast chromoly, MIM or something like that.

Don't know at all But maybe Randall does as he's the AR expert.

[vintagearms]

Depends on the manufacturer:

http://www.midwayusa.com/product/788204/alg-defense-quality-mil-spec-trigger-ar-15-lr-308-small-pin-154-single-stage-matte

[MattyB]

Depends on the manufacturer:

http://www.midwayusa.com/product/788...le-stage-matte

that was easy. I assume thats what your typical mil-spec LPK would include?

I only know that the lower and upper are 7075 forged aluminum and the barrels vary but never really thought about the fire control group.

Thanks for the link, seems easy to figure out but I searched around and had a hard time finding an answer in a forum.

[kcstott]

8620 doesn't surprise me at all that is a very well used and proven steel in the gun industry.
Your M1 Garand and M1A are both 8620 at least they were at one time.

[CGT80]

I don't have a great answer to your question, but I learned something from Randal last week. I asked if he worked on AR 15 triggers. Mine feels like a stock trigger. He said that most of them are just surface hardened, and if he was to work on the surfaces with a stone, it would most likely wear off the hardened surface and the trigger movement may change with wear. He advised me to just use an aftermarket kit for a better trigger.

Is there a different reason you wondered about the makeup of the trigger group?

[MattyB]

I don't have a great answer to your question, but I learned something from Randal last week. I asked if he worked on AR 15 triggers. Mine feels like a stock trigger. He said that most of them are just surface hardened, and if he was to work on the surfaces with a stone, it would most likely wear off the hardened surface and the trigger movement may change with wear. He advised me to just use an aftermarket kit for a better trigger.

Is there a different reason you wondered about the makeup of the trigger group?

I was shooting with my part time fabricator (I run a custom hot rod shop) and we just got to talking about parts of our ARs. We know enough about sheet metal and aluminum but we aren't what you'd consider gunsmiths and inquiring minds wanted to know.

For the record, you should hear the weird things we ponder relating to engines, we spent more than a lunch break reverse engineering a custom V8 engine based on the Suzuki Hayabusa that is available in the top of the line Ariel Atom from 15 pictures. We figured we could build it for half the cost they were asking after looking at the parts. Thats just how we are.

More or less, when you have a complex machine in your hands and you have curious minds like ours, you want to know what its made out of, how its made yadda yadda.

ETA: Now that you brought it up, it would be fun, although probably not worth it, to build a custom trigger.

[CGT80]

My dad, brother, and I are pretty similar. I do some fabrication with steel and aluminum for a hobby and did some for a previous employer. I am into old Chevy trucks, a VW dune buggy, and have experience with many things mechanical. I do as much of my own work as possible or as practical. Sometimes I try to make a better mouse trap, for less money. Sometimes it works and sometimes it doesn't.

Shows like modern marvels and how it's made are right up my alley.

[ott1]

ALG ACT trigger:

Trigger and hammer are made from true 8620 alloy steel military specification castings, correctly carburized, quenched and tempered for high surface hardness.

Disconnector is 1070 High Carbon steel properly Austempered into the spring range of hardness.