View Full Version : M1A doubling

Super B
February 03, 2009, 14:15
My loaded M1a doubles, not just with commercial ammo but with South African and Port. Any ideas?


February 03, 2009, 14:35
Is this a new condition?
Have you recently replaced the stock or trigger group?
Is the hammer following the bolt?
Does it happen when you are following through with a good trigger pull?

Test for "hammer follow'" on an unloaded rifle by cycling the bolt. The put the unloaded rifle on your work bench facing away from you. With you left hand squeeze and hold the trigger all the way back. With the trigger still depressed cycle the bolt with your right hand.

What you are feeling for here is whether or not the hammer is high enough to reset when the bolt cycles. Release the trigger and pull again to see if the hammer stayed back. If it does not, you have hammer follow.

The fix after you test.


February 03, 2009, 18:21
This is common with the Garand type trigger if you "milk" or slowly squeeze the trigger like you would a target rifle. Harder to describe, but what happens is you basically are bump firing the rifle. It's even easier to have happen if you are shooting from a bench. Try a more deliberate pull with the trigger held firmly to the rear after every shot.

Super B
February 03, 2009, 20:38
It's a factory loaded M1a. I haven't replaced anything on it. I was shooting from a bench but i (thought) I had good trigger follow through!!!

February 03, 2009, 21:23

The posts above are good info.

But I want to open another possiblity since you said you thought you had good follow through.

It is good that you recognize follow through regarding trigger squeeze, not pull.

Follow through means you keep the trigger, your finger and your body frozen still while that round travels down and out of the barrel.

Then, not until you have your front sight focused on the target again for the next round to fire, should you release on the trigger to reset the sear again for another shot. Never take your finger off the trigger during a string of firing.

With the M1 Garand and M1A you can feel the sear reset.

If you are not following through properly, which means do not ease on the trigger to reset the sear until your front sight is on the target for another shot, you can easily do doubles.

If you try to reset the sear before your eyes and mind are focused on the front sight on the target for the next round to go down the barrel, you will get doubles.

When I was learning follow through this happened to me very frequently.

Remember to focus your mind on keeping that front sight crystal clear on the target.

Don't let your mind be too preoccupied with getting that trigger and sear ready for the next shot. After one round goes down range, refocus on the target and then ease on the trigger(keeping your finger on the trigger always) to reset the sear and then let another round let fly.

Give that a try. If that's the issue, the doubles will stop and you will save on ammo.

February 04, 2009, 11:45
If it's a loaded M1A it has a NM tuned trigger group. The problem could be that the rear hammer spurs have too much material removed and the disconnector/sear is releasing the hammer without enough over-lap to allow the trigger to catch the front spurs.

Like Rotor suggested, unload the rifle and take it to a work bench. With the rifle aimed in a safe direction, pull the trigger all the way back with your left hand and cycle the bolt with your right. The sear should catch the hammer and hold it back. With the bolt in battery slowly release the trigger, the hammer should now reset and be held by the trigger. Try this several times to make sure it works the same way time and time again.

If the hammer does not reset and falls home against the bolt, that's your problem. Either the hammer or the trigger/sear assembly will need to be replaced, maybe both.

I have seen some pretty shotty NM tuning jobs on trigger groups from SAI. I still own the trigger group that came with my Loaded M1A, and it's horrendous. When done properly, the rear hammer spurs should be in full contact with the sear when the first stage is taken up. But on this trigger group the spurs were stoned at an angle, and it only has the slightest bit of contact. It's just a matter of time before that hammer starts doubling up.

I'm not sure I'm explaining it well enough for the novice to comprehend, so I'll post photos when I get a chance.

Super B
February 04, 2009, 22:51
I did the test you described and the hammer is not following the bolt forward. I may have to alter my trigger squeeze. Maybe a little more "slap"?

February 04, 2009, 23:35
Here's an example of what to look for. With the first stage taken up, the left spur makes contact with teh sear only at the left-most edge; the right is spur is whistlin' dixie. The next photo is of a hammer properly stoned. Both trigger groups were tuned by SAI.

The third photo is of the problematic trigger group, showing the overlap with the trigger once the first stage is taken up. According to Mr. Kuhnhausen, this over lap should be no smaller than 0.020". I haven't measured mine, but it looks small in taht photo: :eek:




Super B
February 05, 2009, 07:33
Mine looks similar to photo one with contact only on one hook. What should I do?

February 05, 2009, 08:12
Take advantage of that life-time warranty.

Super B
February 05, 2009, 10:02
No offense, but if Springfield armory messed it up once, I would prefer to send it to somebody ELSE to get it fixed.....

February 05, 2009, 12:05
Lol! No offense taken. I'm pretty down on SAI for a number of "minor" reasons like this one. I don't own any of their rifles anymore. And I'm not a fan rifles that NEED a life time warranty to get people to buy them.

There's a sticky thread on the M14TFL forum that lists a bunch of M14 smithies (shameless plug: I'm one of them.) Any of them can help you out. If you have a spare hammer that has not been stoned and a new trigger/sear assembly you should send them along with the trigger group. You'll get your unused parts back.

But to SAI's defense: if you send them that trigger group they will fix it for free, and I'm sure they will take better care of it this time around. If you go that route, ask that they use USGI parts if anything needs replacing.

Warbirds Custom Guns
February 15, 2009, 05:11
Originally posted by gunshack
Here's an example of what to look for.
The third photo is of the problematic trigger group


The hammer hooks had to much material removed.
The correct term is "handoff" from the secondary sear to the primary sear.

February 17, 2009, 11:37
Fittment of the trigger group into the stock can also cause doubling. If the stock has been altered at all where the trigger group "locks" into the stock, and the trigger group is sitting to deep into the stock, its screws up the geometry and will cause doubling.

Warbirds Custom Guns
February 18, 2009, 07:54
Originally posted by thecreeper23
and the trigger group is sitting to deep into the stock, its screws up the geometry and will cause doubling.

It's almost impossible to be to deep.
Actually it's just the opposite.
If the bolt doesn't contact the hammer enough to reset on the secondary sear, the hammer will follow the bolt causing a slam fire.

If the trigger group is to low or down to far it could double fire and needs to be set deeper into the stock to make more contact with the hammer.