M14/M305/M1A Test after assembly

[Morpheus32]

Gents,

With all the people upgrading their M305s, I though I would add a reminder for a test after assembly safety check. Whenever you take apart your rifle, swap out the stock or trigger or parts, you should conduct a simple test after assembly.

Firstly, ensure it is unloaded, pull the charging handle to the rear and release. The hammer should be locked to the rear. Place the safety on, and try to pull the trigger. You should not be able to make the hammer release despite moderate pressure. Now take the rifle off safe, pull the trigger...the hammer should be released and make contact with the bolt. Now keeping the trigger pulled to the rear, while pulling the chargin handle to the rear and release...keeping the trigger pulled to the rear and hold. The hammer should be caught by the sear and be locked to the rear. Fire the action, keep the trigger to the rear and cycle the action 4 or 5 times again. The hammer should be engaged by the sear initially and remain locked down. Now with the hammer fully back and engaged by the sear....slowly release the trigger, the hammer should come off the sear and be engaged by the trigger. Pull the trigger and the action should fire.

If at any time the hammer does not engage as noted or fires with the safety on, you have a problem and should not fire your rifle. The problem can be the trigger group parts, the relationship with the stock and the trigger/receiver.

I bring this up as I have a rather troublesome M305 that will fail this test when I use a number of different stocks. If the sear will not catch the hammer...well lets just say it would be interesting....you could have an out of battery firing or the rifle go full auto. It would be extremely dangerous and an out of battery firing could allow you to pack your rifle home in a shoe box...as you come back from the hospital

Jeff

 

[Unregistered]

What exactly would happen?

 

[tenexx]

What exactly would happen?

If the hammer did not engage the sear then the hammer would fall when the bolt came back into battery and fire the round chambered and would continue to do so until the magazine was emptied. I am being circumlocutory as we are talking about something which would get you a conspiracy charge from the F-Troop (BATFE). Nobody talk about shoelaces or matchsticks!

 

[Morpheus32]

If the hammer did not engage the sear then the hammer would fall when the bolt came back into battery and fire the round chambered and would continue to do so until the magazine was emptied. I am being circumlocutory as we are talking about something which would get you a conspiracy charge from the F-Troop (BATFE). Nobody talk about shoelaces or matchsticks!

Actually the out of battery firing was more my concern particularly from a shooter safety point of view. It could also go full auto as well. My comments at the end where not intended to imply something beside it would not be good what would happen. If you did this intentionally to get a full auto activity, you would just as likely have your rifle blow up in your face. No tinfoil hats needed here. The test after assembly is essential to ensure you will not be injured when you next fire your rifle. I would strongly recommend that you take your rifle to a gunsmith or remove the "upgrade" you added that cause the failure.

Jeff

 

[Brobee]

The fix is pretty easy for the most part....the issue stems from dimensional differences in the stock that effect the trigger group/receiver spacing relationship. In 95% of the guns I have seen exhibiting this problem, fixng it involves milling/sanding out a small amount of material from the ledge on the bottom of the stock where the back end of the trigger group sits. The following photographs are of a SAGE stock, however it is no different on a USGI or wooden one:

Before:

After:

For your rifle to be safe, the disconnector in your trigger group MUST catch the hammer when the trigger is fully depressed while the action cycles:

Good luck...

Brobee

 

[Morpheus32]

Thanks Jason. The important issue here is to do the test after assembly so you are not surprised at the range. The diagnosis can be a lot of things and Jason is correct, most are the relationship between the receiver and trigger group. I have one M305 that is very sensitive to this problem....

 

[mdbuckle]

I think this should be a sticky as I do believe this is a saftey issue that everyone should know about.

 

[Brobee]

The subject has come up before, and the same discussion ensued.... however no action in the sticky department. Not sure why...I have seen a large number of M305s exhibiting this problem when paired up with USGI stocks; factor in the potential for serious consequences (out of battery detonation) and IMHO it moves high enough up the risk scale to warrant inclusion with all the permanent instruction on how to dress up your m14/305 with a stock that might cause the problem....

Brobee

 

[Thamok]

STICKY THIS....

or we'll bump it forever...

very good advice

 

[Will I Am]

By the way, where can I find a dealer in Canada thats sells the sage ebr stock, and roughly how much will it cost me....

 

[tps50701]

Bringing this thread back to life, because I have the same problem with my sage ebr.

Approx how much are you required to take off the stock in order to get it to work correctly. I don't want to screw up my nice new stock.

If anybody can help me out, I'd appreciate it.

Thanks, Carl

The fix is pretty easy for the most part....the issue stems from dimensional differences in the stock that effect the trigger group/receiver spacing relationship. In 95% of the guns I have seen exhibiting this problem, fixng it involves milling/sanding out a small amount of material from the ledge on the bottom of the stock where the back end of the trigger group sits. The following photographs are of a SAGE stock, however it is no different on a USGI or wooden one:

Before:

After:

For your rifle to be safe, the disconnector in your trigger group MUST catch the hammer when the trigger is fully depressed while the action cycles:

Good luck...

Brobee

 

[Sniper1]

This thread is so important !

My Norinco M14S is very prone to this problem of the sear not catching the hammer, when pressing fully the trigger while cocking (let's call it the "M14 sear bug").
Here's the story :
- in chinese wood = no problem
- in USGI fiberglass stock = sear bug. Bug eliminated by slightly filing the ledge on the bottom of the stock where the back end of the trigger group sits.
- in Troy MCS chassis (MOD 1) = sear bug again.

Now my hesitation is with filing my Troy MCS chassis. Reason 1) it very expensive. I don't want to ruin its resale value. Reason 2) it does have trigger group adjustment screws (try them, but doesn't help)... could there be another detail, tip or trick i'm missing with the MCS Mod 1 system ?
Is there another way to get rid of this "sear bug" ? ex: filing the back bottom lip of the trigger group to reduce its thickness ?

Pic of the "sear bug" with my M14s in Troy MCS

Pic of the portion of the stock that I should be filing down (but as mentionned above, i would greatly appreciate some advice to an alternative solution). Notice the adjustment screws are slighly exposed. However, if i raise them more, it just causes difficulty to lock the trigger group in place, with no positive effect on the "sear bug".

Here's when I drop the trigger group in place. I have the required 1/8" clearance between trigger and guard (per Troy instructions).

Trigger group in place. Looks normal. However, I can't shoot it like that. too dangerous.

Any advice ?
Thanks

 

[Hungry]

Okay sportsfans:

I'm am out of my experience set here with the TROY system. I'm going to fall back on my Principles of M14 advice:

* stick with the cheapest (most welfare) fix if possible (know anybody with a USGI Trigger group to experiment by swapping?)
* stick with the most temporary fix when possible (try another Norc M14 trigger group, hopefully made by a different high school shop class in China... I'm serious here...)

* stick with a the fix that most easily returned for factory condition (switch back to a USGI glass stock and install / screw on some rails)

* Avoid altering factory condition unless you are totally committed to the desired outcome and you do have spare parts when you fzck up (done this many times)

I realize that I am not capable of prescribing a fix when I'm:

1) far away from manipulating this platform / trigger group combination
2) Have such a limited experience set

Any Troy System experts ready to chime in?

Barney

 

[Sniper1]

Oh, so that's why I should have bought TWO norinco M14's ... stupid me.

 

[pig boots]

m14 stock

where can I get a usgI stock for the m14 in the peoples republic of Canada?

 

[toyboy]

sniper1,if you need a trigger group to try,norc or gi,i may be able to meet you at the range(ruisseau noir in terrebonne).
let me know as i don't know in which part of this socialist paradise (quebec) you live in.

 

[Sniper1]

Thanks toyboy, but I already had a friend gunnut come to my place. We only tried his Norc trigger group in my MCS chassis and M14 receiver. The result was that it reacted the same way as my own trigger group : sear not catching hammer when trigger fully depressed. So the next test is to do an entire rifle swap to rule out that the MCS is out of spec. Because of what we know already; Norinco vs Troy QC departments... i'm 99% confident that the out-of-spec issue comes from my Norc M14 receiver... not from the troy chassis.

here an interesting picture I took; if i take out the bottom chassis part and take up all the slack between the trigger group and receiver (using a tie-wrap), you can see that it is actually possible for this receiver-trigger group set to work together. Their rearward portions just need to be close to each other... well, closer than usgi specs.

 

[Sniper1]

Just to say my problem got solved by the CRAFM gunsmith. The fix is exactly was Brobee described a couple posts above.

 

[Lazerus2000]

1.70" from bottom of receiver to trigger pad ...
set it to this measurement, and you should NOT get hammer slipping.

PS: Some bolts, even GI bolts, are smaller at the rear, and some receivers, especially Sproingfierld, have the rerceiver bridge hole a bit too large.

This raises the hammer camming surface at the back of the bolt, which again can be enough to make the hameer slip.

hope this helps,
LAZ 1

 

[lejarretnoir]

I had the slamfire type experience. A Norc M14 that somebody attempted to do a trigger job to by stoning the hammer hooks a little too much. The sear would not hold it after firing. I corrected it by removing some metal at the back of the trigger where the sear comes against bringing it in slightly. This solved the problem, but the single stage pull was harder. Ended up replacing the hammer, trigger and sear with new genuine M14 parts. Very nice pull and still had to remove a little metal from the trigger for the sear to engage the hammer hooks. I think this particular action and /or trigger group has just a different setup, but all is well. Nice light 1st stage and a good 4.5lb let off. No more problem.