Colt Rifle Sear Block Removal


August 20, 2006, 08:56 PM
Geissele’s web site states that the Geissele triggers will not work in a large pin Colt with a sear block installed. Quarterbore's Forums ( shows a method to remove a sear block installed with only a single small blind pin, but states this method will not remove a sear block that has a pin going all the way through the receiver or with any additional pins.

Since I am located in CA only a gunsmith with a CA Assault Weapons Permit may work on my registered Colt lower. If I want to ship the lower out of state to a gunsmith I must also use a FFL dealer with a CA Assault Weapons Permit to ship and receive the lower. Unfortunately there are no gunsmiths or FFL dealers located a reasonable distance from me in Northern CA so I am stuck trying to do this myself. Has anyone here had any success removing these sear blocks?

Here are pictures of the different Colt sear block installation methods.

Any guidance is appreciated.

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Tejas Gunwerks
August 20, 2006, 09:30 PM
I just mill them out. They also have a roll pin in the bottom of the block. What you are left with is a hole in the side of lower. You can carefully fit the existing pin, peen it from the inside and loctite it. Other wise you are left with the hole or holes or you can find some other material to fill them. Perhaps a press fit aluminum rod.

Jim Watson
August 20, 2006, 09:45 PM
My CAR-A3 looks like your picture but what was there was two blind pins into the sear block from either side, not a through pin; and a small blind roll pin in the bottom. My FLG took it all out with a milling machine. I have seen pictures of a brave soul removing them with a Dremel but it takes a steady hand to keep from skinning up the receiver.

August 21, 2006, 08:04 PM

I have access to an Emco Compact 5 with a milling head. I don’t have experience with this, but I will give it a try. What type of milling bit do you recommend? Are the sear block and pins hardened requiring a specific type of bit or technique?

Also, any suggestions on how to secure the lower to the table without damaging the exterior finish on the lower?

Here is the technical specifications for the milling attachment on the Compact 5.

Technical Data Of Vertical Attachment

• Input power: 200W s3-60% ED
• Number of speeds: 3
• Speeds: 380-1600rpm
• Maximum working height: 200mm
• Working radius: 82mm
• Sleeve stroke: 30mm
• Weight: 6.5kg



August 21, 2006, 08:11 PM

My CAR-A3 has Colt’s precision rifle trigger from the factory and it's not bad. The top two lowers are the ones I want to remove the sear blocks from to install the 2-stage triggers in. How did you fill in the openings left by removing the pins.

Also, thanks for letting me know there are two blind pins instead of just one pin that goes all the way through.


Jim Watson
August 21, 2006, 08:47 PM
I just shoot the rifle with two holes showing in the receiver sidewalls. I kept the pin heads - they are like a flathead screw with shank smaller than the head that shows - for the purpose of gluing in the holes, but have never bothered. A spit in the eye for timid gunmakers.

September 1, 2006, 01:37 PM

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