Is it legal to mill out the sear block on a lower receiver?  I thought I had seen BATF info somewhere saying that the removal of the metal (milling) is legal and does not constitute a conversion.

Any answers?

Thanks

AR15nut,

It is legal per 'Stokes' to remove the sear block.  I ask the same question a few weeks ago and got the same answer from several people.

But it is illegal to mill the enter walls of the lower.  As long as you do not mill the enter wall down there not a problem.  

Remove the pin and the sear block will come out.  

Stokes, if you don't mind me asking what did you pay to have them milled? John

Must of been a Colt, reason I ask I'm an 07,SOT just wondering if there's that much of a demand for that. John

Stokes,

Correct me if I am wrong.  But what holds in the Colt sear block?

I thought the sear blocks were pinned in, and if you remove the pin the sear block should come out?

What I was talking about is milling out the lower receiver so an auto-sear would fit, which is illegal.  Milling out the sear block and damaging the enter walls of a lower receiver would also be illegal.

golfgunguy:  The colt block is held in by a hardened blind pin.  Drilling or milling of some sort is required to remove it.

It is not illegal to machine out a semi-auto AR15 to complete M16 specs, as long as you don't drill the auto sear hole.

Circuits,

The hole and pin that holds the sear block, is it the same hole and pin that would hold an auto sear?

Or does another hole need to be drilled in the lower to hold a auto sear?

The block pin is roughly the same location as the auto sear hole, but it's bigger, and I believe only located on the right side of the receiver.

(Quote from AJ from the old AR15 Forums)

Author: AJ
Topic: Colt sear block removal
Junior Member posted 01-10-2001 20:12

Before you drop $200 to have somebody cut on and refinish your $800+ receiver to remove the sear block consider this:

As an engineer and perfectionist I like to keep my stuff looking factory. I removed the block on both my ARs because I could and they look exactly like they did before except the block is gone. Here is how to do it.

1. Place the receiver in a padded vise

2. Drill a vertical hole in the block(correct size for a #8 machine screw with hex head) 3/8" to 1/2" deep and centered at the intersection of the "L" in COLT (centered over the block pin).

3. Thread the hole with a bottom tap.

4. Fill the hole to the top with Marvel Mystery Oil and start the screw.

5. Slowly tighten the screw and you will notice the pin begin to protrude out of the receiver.

6. When the pin is about 5/16" protruding from the receiver the block should wiggle fore and aft.

7. Grab the block with a pair of vice grips and gently wiggle it while pulling vertically.

8. Once the block is out the roll pin may still be in the receiver. Repeat step 7 if so.

9. Knock the block pin back in flush with the receiver side.
DONE..isn't hydraulics just great!

Use a carbide tip drill, the block metal is hardened.

This is only information. I am not responsible for your mistakes. If you don't feel comfortable doing this send me $30 and your receiver and I will do it for you, however since you don't know me from Adam I suggest you take these instructions to a competent gunsmith and have him do it.

This has nothing to do with the topic, but what is an enter wall as mentioned above????

I believe they meant "entire"