Various reports of slam-fire or doubling in semi-auto rifles

Slam-fire - Fulton Armory.  Fulton armory may be the most respected source of expertise about semi-auto rifles, anywhere.  This article speaks of design flaws and doubling in the original M-16 platform, and that manufacturer Colt eventually replaced the floating firing pin in Colt production rifles with a lighter firing pin to correct chronic doubling problems.
http://www.fulton-armory.com/SlamFire.htm

A discussion on M1’s doubling from the Civilian Marksmanship Program
http://www.odcmp.org/new_forum/topic.asp?TOPIC_ID=75333&SearchTerms=doubling

Another article about doubling from Fulton Armory
http://www.fulton-armory.com/SlamFire2.htm

http://www.thehighroad.org/archive/index.php/t-114401.html
was test fireing a AR parts rifle,that I got at a show sat. luckey I use 1rd,2rd,etc method to test with,as rifle double fired at 2rds loaded. with 3rd loaded,it doubles and chambers the 3rd round.
this being my first AR,this was not a happy feeling. what do i need to look at,change out,before the knock on the door?

http://www.thehighroad.org/archive/index.php/t-84754.html
I have an ORF G1 FAL which I ordered in Feb and received in April. I am happy with the build time. I have not yet worked all the bugs out of the rifle though.

Problems:
1. FSE trigger group allowed the hammer to chase the bolt forward occasionally causing the rifle to double. I fixed this problem by putting a DSA fire control group in my rifle ($60). The contacting surfaces of the DSA group are larger and the problem has been solved. Can someone tell me how to contact First Son Enterprises so that I can get them to replace these parts (I want to sell them).

2. The gas piston was apparently too tight in the gas tube which caused the gas tube threads to strip as the gas tube traveled rearward during firing. ORF sent a replacement gas tube and I cleaned the inside of the tube and sanded the gas piston until they slid freely together. No more problems so far.

3. The trigger is Awful. I can unload the rifle, put the muzzle down, hang a 2.5 pound weight on the charging handle and lift the rifle by the trigger without the hammer falling. All of my other rifles are no where near this difficult to pull the trigger. I replaced the trigger return spring, but no improvement was gained. Any advice would be appreciated. Especially a reduced power trigger return spring. (I think that would be better than cutting the spring.)

4. The rear sight wobbles. I hear this is common with the FAL and my rifle is actualy just as accurate as my other rifles, so I guess the sight settles into the same place after every shot.

5. The rifle is only 95% reliable. It frequently jams on the first or last two rounds in a magazine. It seems to favor alloy magazines as it has not jammed with the aluminum mags yet, but Steyr and FN mags produce occasional jams. (Portugese surplus from Aim & gas setting does not affect these jams as it can jam when allowing a locked open bolt to close.

Other than these problems, the rifle is fine.

If I had it to do over I would have bought a DSA rifle because between this rifle and my M1A, I am tired of working on "new" rifles trying to get them to be reliable. The M1A is working 100% now, but it took a lot.

Thanks for any suggestions and I hope this helps someone.

http://www.thehighroad.org/archive/index.php/t-4124.html
I had a strange occurance with my '43 SA Garand this weekend. I was shooting 1980 Danish Surplus (the stuff that comes in Enbloc clips).

Twice, the rifle slamfired the second round in the clip (ie. Two round burst with the first pull of the trigger, the other six shot normally). The first time got my attention, but I had the sling wrapped securely around my arm and knew the rifle wasn't going anywhere, plus I figured it was probably a sensitive primer. Then about three clips later, it did it again. Also only on the second round in the clip. At that, I packed up the rifle and ammo and shot my Mosin for the duration.

I took the rifle apart when I got home and found nothing apparently wrong. I pulled the firing pin expecting that maybe it was gummed up, but it was pretty clean and rattled freely in the bolt. Is there anything else I should look for? Could weak springs cause this? I have a Wolff spring kit that I plan on installing.

I put about 600 rounds through the rifle before this with no problems at all. I do use grease at the proper lubrication points.

http://www.snipercountry.com/HotTips/Slamfire.htm
Back to M1A/M14 rifles for a minute.
While shooting last time, I let a buddy shoot my S.A. M1A with cheap UMC ammo. While shooting it, there were times when it would slam-fire. This hasn't happend with match ammo, but it still bothers me that it has done it with other ammo.
Can someone give me the low-down on how to cure this problem?

http://www.snipercountry.com/HotTips/Slamfire.htm
My M21 slamfires with Fed F210M match primers... it's caused by the heavy weight of the firing pin hitting on its own speed.
CCI makes a hard military spec primer for this problem... one for the .223, and one for the.308... I think the number for .308 is CCI #34. Check with your dealer.

From : http://www.surplusrifleforum.com/viewtopic.php?f=43&t=83934&p=609396&hilit=double#p609396
 
I bought my egyptian 8mm FN49 about 18 months ago. It has a 2 piece firing pin. While firing commercial (Igman) ammo, I had about 5 slamfires/double fires in the first 150+ rounds. I then had an out of battery fire (very loud) - buggered up the extractor, ripped the base off the cartridge, split the stock forward of the mag & behind the receiver, & the return spring rod has never been the same ( sort of out of alignment ). Got it all fixed up & have had no problems with Yugo 50's surplus ammo (300+ rounds) . Will never fire commercial ammo out of it again. Just 2 weeks ago, had the rear trigger guard bolt drop out of the weapon while at the range. It had sheared off just below the receiver. it looks like it had a hairline crack from the out of battery, and finally gave out. i've ordered a replacement. These things just don't like soft primers from what I can see. I even tried to duplicate it with a dummy round (live primer, no powder), but no matter how many times I chambered it, nohing happened. go figure. Still love the rifle.
 
 
From: http://www.surplusrifleforum.com/viewtopic.php?f=40&t=77137&hilit=double+fire
  Have a Romanian WUM-1. Recently upgraded it to 922r compliance so I could us hi cap mags. Took it to the range, and out of 75 rds, had two instances of double fire. Rifle has never done this in the 20 years I have had it. Tore rifle apart, firing pin is good and loose. Inspected the newly installed FTG and can see absolutely nothing wrong with it that could cause the problems I had. Anyone else have this problem and what did they do to fix it?

Don't need any problems with the authorities.

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