Really impressed with my SI Defense .308 lower. Good deal, features until....
The rear detent hole is threaded for the included screw so you can use whatever grip without issues––except it's granted me a whole new type of detent spring flyer. A straight long push on the end of a very thin allen key, fighting a snappy, wobbly spring to start the threads. I send the rear detent screw and spring flying ten or so times, getting really close until I lose the detent spring into the great nowhere. To the box of AR parts. None left. Ordered four more in case. If I lose the small screw, I'll be screwed and on the phone with SI defense.
Anyone build on one of these? Tips?
Small piece of brass tubing from a hobby shop makes a good spring/set screw sleeve. Slide the tubing over the assembly to keep it lined up with the hole as you start the screw.
You can also use a plastic ball point pen ink tube if the spring and set screw will slide thru it.
When I thread my receivers for the set screw, I usually clip a couple of coils off the spring to make up for the shorter compressed length... It will also reduce the spring tension when you insert the set screw...
I also place the tips of my thumb and forefinger over the end of the allen wrench, the set screw, and the spring until the set screw contacts the receiver...
Cut the spring down. It just needs a small amount of compression to keep a little pressure on the detent pin.
Cut a short piece of drinking straw and use as a guide.
I'VE BUILT TWO SI-DEFENSE GUNS AND THEY CAME OUT PERFECTION 5.56 & A .308. ALL THE PARTS WENT RIGHT IN AND I'VE HAD NO PROBLEMS.
GOOD WORKMANSHIP AND WHEN I CALLED THEM THEIR CUSTOMER SERVICE WAS SUPURB!
I HIGHLY RECOMMEND THEIR STUFF!
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