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9/19/2017 7:27:10 PM
Posted: 10/22/2002 6:05:12 PM EDT
And the troubleshooting link does not work, so, here's the problem;

20" A2 on an Essential Arms lower. Has always been well lubed and worked well with Rem. UMC and Winny white box 55gr. FMJ ammo.

One day it started to double, so, I've replaced the hammer (which appeared kinda worn at the point of the hook/disconnector?). I've also replaced the hammer spring, sear, and the small spring that rides between the trigger and the
sear (please excuse nomenclature ignorance).

I'd love to tell you that solved the doubling problem, but I can't tell. I haven't been able to fire the rifle because now, when I charge the rifle the hammer pivots back too far and that hook gets stuck on the fwd. portion of the sear. Trigger will not move. I've pushed out the hammer pin and reassembled only to have it happen like that again and again.

So, two questions;

1. What have I done wrong?

2. What is that #@*&^%! hook there anyway, I can't see it serves any purpose.

BTW, the parts were purchased from an AR15 advertiser with a good reputation.

Thanks in advance for any help.
Link Posted: 10/22/2002 7:53:34 PM EDT
Ok, lets start by calling the parts by the correct names.



You call it a sear

Disconector spring-
the large end goes down into the trigger slot.

Your problem with the old fire control group is as follows.

The disconnector was not retaining the hammer when the carrier slammed home, and the disconnector became "out of timing".
By "out of time", the hammer was released before the trigger contact edge/lip could get under the hammer contact edge/lip.

To fix the old fire control group, all that was required was to replace the worn disconnector spring, and re-time the disconnector by removing metal from the front/bottom edge, to make the disconnector release the hammer later in regards to the trigger reset.

The purpose of the disconnector is to retain the hammer once the carrier has cocked the hammer back. If the disconnector was removed, the hammer would follow the carrier, then jam at the firing pin. This is a safety feature, and the reason that there is a step in the top of the hammer.

On your new FCG, you may have one of two problems.
1. You are using a large hole FCG on a Small hole receiver, with small hole pins.

2. You have installed the FCG wrong and the wrongly installed springs are binding the action.

What I suggest is that you spend some time reading the repair manual, then pull the parts to check size and correct installation of the FCG.

Hope this helps.

Link Posted: 10/24/2002 4:32:24 PM EDT
I put the old hammer and disconnector back in along with another new discon. spring and the hammer no longer hangs up. Cycling by hand and dry-firing, everything seems to be in order.
Will fire tomorrow and see if doubling still is a problem....if so, might replacing the disconnector solve this? I'm not clear on where the disconnector needs to be filed or polished, the only part that appears to see any wear is the front top edge of the "hook" at the top of the part.
Link Posted: 10/24/2002 7:09:36 PM EDT
The way to test and fit is as follows;

Cock the hammer back to the disconnector while holding the trigger. Slowly release the trigger until the hammer is released from the disconnector and catch by the trigger. The disconnector should release the hammer about .030 from the trigger coming back to rest.

Note: Put your hand in front of the hammer incase the trigger does not catch the hammer. This will prevent the hammer from crashing into the receiver.

To tune the disconnector, you remove metal from the forward/bottom of the disconnector where the disconnector make contact with the front of the trigger. By removing metal, the disconnector is camed forward and releases the hammer later in its movement back to rest.

Hope this helps.
Link Posted: 10/25/2002 3:59:18 AM EDT
Jake, just replace the hammer & disconnector.
Tuning fire-control parts is best left to those with considerable experience & knowledge.
Not that you can't or shouldn't....just not yet. Get some more time & experience with the weapon first.
My personal rule: If you can't reliably & easily take it apart and put it back together yet, you are are not ready to modify it.
Link Posted: 10/25/2002 9:18:47 PM EDT
He has a Essential Arms lower. On some, the FCG has to be fitted to work. As he stated, he did change the FCG and the new group was a no-go.

But, I do agree with Royce, you may want to take the rifle to a smith and have him fit the parts. I often forget that some of you are fresh to the AR-15 and I go way beyond what you may be capable of achieving on your first problem solving with the rifle.

Royce, Thanks for the reminder.
I have been bonding with my FMP,just got the upper back after 14 months. I have been fine tuning the rifle and posted during a break in the action. Also, I just received my new OD green K-var stock and have been fitting it to my new favorite AK. So you see, the winter projects have began and I have been posting in the wrong state of mind for the newbies.

Glad to see you back!!!!!!
Link Posted: 10/26/2002 10:05:57 AM EDT
Dano, you re a wealth of knowledge...we just have to keep a leash on you, or we won't be able to keep up! I think that there should be another board: Advanced Tuning of the AR. I'll just watch, listen & learn on that board.
Thanks for the insight to the Eseential Arms Lowers. You say that they often need fitting? Is this a particular production problem or a general lack of quality control. We used to see things like this with Olympic lowers..poor finishing at the takedown pin holes and tighter-than-they-should-be mag wells.
Link Posted: 10/26/2002 3:56:40 PM EDT
Back, before the receiver manufactures where holding ISO 9000/9001 standards, there where companies like EA and Sendra. Although the receivers are good, then did differ in regards to the variance to the Mil spec for the receiver.

Now the receivers are all CAD milled from CNC machines. Which means that if one has a problem, all will have the same problem with that production run. On some receiver lines, this can be a good thing. The RRA receivers are milled to minimal spec, And when assembling, they form the basses for a tight fitting rifle. On the DPMS, the front take down ears(inner distance) are milled .500+/-.001 and not the .496 RRA keeps. If you know this up front, then you spec your Upper receiver (kit) to match the known spec.

On his EA receiver, the FCG holes are at the max or more of acceptable MIl spec variance. The clue was when he dropped in a New FCG and it was binding.
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