No, you don't REALLY need them. The stock pins work just fine with a trigger group that has no problems. However, if you feel you need them, then no harm is done.
Funny how things get started. As I heard it (could be wrong) a bunch of factory hammers got made 20 years ago without the "J" spring installed inside the hammer.
Just a little dinky tiny spring steel length of wire bent into, you guessed it, the letter "J". Goes way inside the Hammer and centers on that middle groove on the pin.
Anyway, a batch of AR-15 SP1 hammers got loose in the after market that worked fine until you fired the rifle 5 times, then the hammer pin walked out of the receiver.
When the hammer pin "walked" the rifle stopped. Quick examination reveled the missing "J" spring. The "best" fix was to make up a batch of pins with circlip grooves
At each end of the pins, plus an extra length sosss small circlips would physically hold in the pins instead of that missing "J" spring. Crazy how things happen sometimes.
The "fix" was actually better than the first design. Yeah, such hammer and trigger pins look odd....but they work fine. The trigger and hammer float. Match triggers use them.
Leaving out "J" springs did happen. It also crippled the realibility of the Sterling made Armalite AR180 rifle. Labour problems with quality control issues. Thanks. HB of CJ
