Hello.  I started putting a new lower together, put the bolt catch spring in, and then the plunger, and it went down and won't come back up.  What to do?

Thanks.

Are you sure the spring is in? Is the hole out of spec?  try some light oil and try to get it moving with a small punch depress it several times and work the oil in to free it.

Hey, thanks for the help.
Spring is definitely in.  I got it to move up and down a little bit and spring back, but it went back down again and won't come back up yet.  I'll let it soak for a bit.  I can grind off a little bit of the plunger if/when i get it back out.  Maybe the spring is dead/weak too?

stuck back down again, not moving.
:(

Is it the right spring, some people have switched the disconnector and plunger springs in the past.

I have had this problem too. Its a RRA lower and I think it has a little burr. I now know to check for burr's. I tried what you are doing and it really did not help, so I finished assembly and used it like this. I think it will eventually free up. Don't know what else to do.

Chinook3

Um, well you've already done it so it doesn't matter.  But never assemble a weapon when you know something isn't working.

Most likely all you needed to do was chase the lower with a drill bit and maybe a needle file to remove a burr.

Either way you should have solved it before assembly.

Same thing happened to me and here's what I did.

I had a Bushmaster lower and a gun show parts kit. I laid out all my parts first, and they were all sized correctly, I had every spring and detent sorted out. I even had extra detent springs. Probably in case I launched one across the room during assembly. I always ream out any holes before inserting pins, springs, etc. to clear out any burrs or residual gunk from finishing procedures.

My bolt catch spring went in the hole just fine, and so did the little pin. When I tried to push it in and out a few times, before installing the bolt catch and retainer pin, it wouldn't come out. I tried oil. I tried WD40. I tried CLP. I tried PB Blaster. I smacked that lower against my hand so hard I bruised my palm. But, to no avail, that pin and spring were IN THERE!

So, what I did was this. (And the AR gods have smiled upon me because this rifle works perfectly.)

*I removed the magazine catch/release button and spring.
*From the right side of the lower, I drilled a small hole, 1/32, up at an angle into the bolt catch spring housing from the mag release button hole..
*I then used a small piece of wire to push the spring and pin out of the lower.
*Then I used canned air to blow out any cutting oil or drill shavings.
*I put a small dab of engine assembly lube on the spring and pin, then assembled the bolt catch without any further problems
*I reassembled the mag catch/release as normal.

I have had zero problems with this rifle. All the movement takes place in the trigger housing, and the upper receiver. The hammer never strikes the mag-well wall unless there is no upper on it. I personally have over twenty years of working with my hands and with tools, and was confident that I could drill this hole without ruining my weapon or it's functional capability. One wrong move, a broken drill bit, whatever, and I could've marred the finish on my lower forever. But I didn't. This may not be the solution for you, but it worked for me.

Here's the rifle I completed with the lower, and it is now about 20 months since I assembled it.

Good luck!

So if I wind up leaving it in , what could go wrong?  Assuming it never works itself free.

And thanks for all the responses.

I had one where I slammed the receiver on it's side on a padded table cover about 15 time but it eventually came out. Sounds bad but the padded cover kept the receiver from damage.

Then i put the correct size drill bit in the hole and hand turned it to remove any burrs.