[tgs]

I want to install a Jard 3# trigger assembly in my Colt AR15 Match .223. I understand that it is neccessay to clearance the sear block. What is the initial function of the sear block that does appear in most Colts? What is the risk? I read it can be done with a dremmel. Can you tell me if Im getting into something best left alone? What purpose does this block serve. It is held in place with a drift pin and what if it didnt exist (removed)?

[Jim Watson]

I put a Jard trigger in a Colt with sear block. Colt puts the sear block in their ARs (and uses odd size action pins) to keep an American Commoner from putting in M16 parts and maybe involving them as he gets himself sent to jail.
It is necessary to take out the sear block to put in the Jard. I had read and even seen pictures of the block being removed with Dremel, but being NRA Mechanically Inept, I took the whole mess to my gunsmith. He chopped out the sear block on the milling machine. The blind pins fell out and I now have a couple of superfluous holes in my action. Shoots great, though.

The Jard took a lot more work than the instructions indicate. Maybe mine was a lemon, FLG says the previous one he put in was no trouble. Good luck.

[mrmeval]

Some info
http://www.quarterbore.com/nfa/dias.html

Some info on how to remove it.
http://www.quarterbore.net/forums/showthread.php?t=184

The sear block was colt trying to prevent a drop in auto sear from being installed. Also other modifications were done to the receiver to preven M16 fire control parts from being installed.

No other manufacturer has bothered to do this so you might want to get another non-colt lower with all the normal internal parts and stick your aftermarket trigger in it along with the upper, pistol grip and buttstock. That way you won't ruin any resale value of the Colt. If however you want to hack on it that link might help also you should ask on http://www.ar15.com as that's the place for EBRs.

It should somewhere near 150 for a lower and internal parts.

[tgs]

that explains it all;)
My guess is that about any trigger replacement will require the block be removed. Jard, Timney etc.
Thanks for all the good info and links.

[Gewehr98]

I have the same sear block in my pre-'94 Colt Competition HBAR, and had to research what options were available to me with respect to aftermarket triggers. I bought the JP Enterprises single-stage adjustable trigger kit, and it DID NOT require modification or removal of that pinned-in steel block, clearance was just fine. Just remember to order the one with the proper pin sizes for your particular Colt. ;)

[tgs]

Sounds like from what I can find out its a good route to go and will probably order Tues. Thanks for the info.