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Offline TexasRedNeck

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Perplexed with FTF malfunction
« on: December 31, 2015, 10:14:12 PM »
Shooting the LMT SBR tonight with the PVS and I got constant FTFs. Never ever had that happen on this weapon.

I cleaned it and put 3-4 rounds through it a few weeks ago. Stuck a mag in it and it would fire maybe 2 rounds and go FTF with the bolt over the top of the round with the round half fed into the chamber. 

Seems lubed ok but tomorrow I'll break it down and re assess.

On a separate note I think I need to adjust the Giessele trigger. I got a triple out of it and a double or two.


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Offline Atkinsmatt

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Re: Perplexed with FTF malfunction
« Reply #1 on: January 01, 2016, 09:48:45 AM »
Could be a bad mag
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Offline Flyin6

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Re: Perplexed with FTF malfunction
« Reply #2 on: January 01, 2016, 09:58:43 AM »
Mag spring weak?
Mag follower ganked up?
Either way, test your dually wheel weight using the mag as a scale!
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Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #3 on: January 01, 2016, 10:06:45 AM »
I'll try another mag. Gonna lube the bolt a bit more. Possible it could be short stroking but with the added back pressure from the can, i doubt it.


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Offline BobbyB

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Re: Perplexed with FTF malfunction
« Reply #4 on: January 01, 2016, 11:45:34 AM »
Could be a bad mag


Mag spring weak?
Mag follower ganked up?
Either way, test your dually wheel weight using the mag as a scale!


I'll try another mag. Gonna lube the bolt a bit more.


X3.

Pull the mag apart, stretch the spring slightly, clean the inside of the mag, clean the follower.  Soak the spring and mag and follower in a cleaner, then scrub the inside, let dry then reassemble with a light coat of lubrication.
So, Bobby...being the calculating trained warrior NCO that you are.  Take the appropriate action, Execute!

Offline Higher Caliber

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Re: Perplexed with FTF malfunction
« Reply #5 on: January 01, 2016, 02:28:58 PM »
I'll PM you my addy. I'll get it fixed and make sure it stays fixed for a couple of years


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Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #6 on: January 01, 2016, 05:26:38 PM »
You bet. I'll leave the can and NV on it too !


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Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #7 on: January 01, 2016, 07:03:52 PM »
Well. Put a brand new mag in it. Ran about 25 rounds before it malfunctioned.  Lubed the bolt and ran through the last 5 ok. Will have to run some more through it tomorrow. Now I'm going to blame BigDave because the bolt won't stay open now in last round.  SMH.

I probably cleaned it too much. I think it likes to be dirty.  And boy does that can put dirt in it quick.


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Offline JR

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Re: Perplexed with FTF malfunction
« Reply #8 on: January 02, 2016, 02:46:43 AM »
You running the same ammo or something new?

Maybe check the gas system. Sometimes a little something gets in there.

I won't mention a limp wrist,,,,,,,,,,,,,,,,,,,,,,,,,,,,,  ::)
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Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #9 on: March 22, 2016, 09:29:13 PM »
Ok guys, haven't been thinking about this until tonight.

I'm starting to think it may be a buffer spring issue.  I've always run this weapon suppressed.  It probably has 5000-6000 rounds down it.  I'm guessing the overload of gas is hammering the buffer and spring and the spring is getting weak and its bouncing back so fast it's getting a bolt override malfunction.  I've run a brand new mag, the gun is freshly cleaned and I still have the same issue.

I'm considering ordering new buffer springs and maybe an H2 buffer to slow the bolt down since this is a 10.5 inch barreled short gas system running much higher pressure because of the suppressor.

What do you guys think?  Sound theory here?

Edit: the spring measures right at 10 inches which is below spec from what I can tell.
« Last Edit: March 22, 2016, 09:43:40 PM by TexasRedNeck »
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Offline stlaser

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Re: Perplexed with FTF malfunction
« Reply #10 on: March 22, 2016, 10:38:47 PM »
If you think it's over pressurized I would swap out gas block for adjustable unit. I had to do this on the 308 I built. The h2 buffer is a band aid.....

Edit: with that said if you think spring is weak maybe replace it & buffer with quality unit before you dial in new gas block.
« Last Edit: March 22, 2016, 10:40:10 PM by stlaser »
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Offline JR

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Re: Perplexed with FTF malfunction
« Reply #11 on: March 23, 2016, 12:54:27 AM »
What about a spiral gas tube. Not uncommon with a short barrel AR. That and a new spring with an HD buffer.
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Offline BobbyB

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Re: Perplexed with FTF malfunction
« Reply #12 on: March 23, 2016, 02:14:12 AM »
Buffer spring, possibly gas block.
So, Bobby...being the calculating trained warrior NCO that you are.  Take the appropriate action, Execute!

Offline OldKooT

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Re: Perplexed with FTF malfunction
« Reply #13 on: March 23, 2016, 09:49:38 AM »
I have nothing to add. Except a burr in my gas tube did the exact same thing. Still have no idea how that materialized.

 



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Offline cj7ox

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Re: Perplexed with FTF malfunction
« Reply #14 on: March 23, 2016, 12:08:07 PM »
Due to the suppressor, I'm going to say too much gas pressure. Adjustable gas block should solve your issues. Have you tried to replicate the malfunction without the can?


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Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #15 on: April 01, 2016, 09:08:03 PM »
Well I think I may be on to something. Old spring next to new spring. I'm also investigating adjustable gas block


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Offline JR

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Re: Perplexed with FTF malfunction
« Reply #16 on: April 02, 2016, 01:43:11 AM »
I would say more spring and buffer. By the time it clears the barrel the system is going to work or not. The really little extra pressure from the suppressor is to little to late.
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Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #17 on: April 02, 2016, 08:06:54 AM »
Yes, Nothing about the factory gas block will keep the system from cycling.  An adjustable gas block will however reduce the wear, cyclic rate and the amount of fouling in the chamber (which is significant)
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Offline OldKooT

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Re: Perplexed with FTF malfunction
« Reply #18 on: April 02, 2016, 11:03:40 AM »
Do you feel the fouling is increased with the suppressor?
Norm

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Offline stlaser

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Re: Perplexed with FTF malfunction
« Reply #19 on: April 02, 2016, 12:06:07 PM »
Reality is the ar with a standard non adjustable gas block leans to the side of over gassed. My guess is so that they can run just about any ammo. Now in this instance we are talking about TRN who as particular as he seems to be most likely runs one or two standard rounds through his gun & if I had to guess the end of each round has a splash of automotive grade Chevy red paint that has been buffed & polished to a high luster. Now you may think I am a smart butt in that last comment but quite the contrary. I prefer pigs blood on mine is all........ ;)
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Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #20 on: April 02, 2016, 12:53:44 PM »
Sean, some of the Privi does have a red ring around the bottom of the primer....jus sayin.

SS109, and M855. With a preference for LC.  No wolf unless I want to run malfunction drills


I run only mil spec ammo and reload to mil spec with H335 verified over a Ohler Chrono

Koot, yes, the back pressure created by the can increases the gas pressure immensely.  That really over gasses the bolt and slams the hell out of it if it is not moderated in any way.  It also fouls everything including the mag.  Thtas why some of the Spec Ops designated marksmen rifles have a switch block with two settings.

Thats the first buffer spring I've ever worn out and its soley because the weapon has been run exclusively suppressed for about 5000-7000 rounds.

http://www.syracordnance.com/collections/gas-blocks/products/gen-ii-750-adjustable-low-pro-solid-gas-block

http://slrrifleworks.com/index.php?route=product/product&path=57&product_id=582

Probably give one of these a try
« Last Edit: April 02, 2016, 12:55:50 PM by TexasRedNeck »
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Offline stlaser

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Re: Perplexed with FTF malfunction
« Reply #21 on: April 02, 2016, 03:23:17 PM »
TRN, I believe we have some of that privi in house in stock even..... :)


Sean, some of the Privi does have a red ring around the bottom of the primer....jus sayin.

SS109, and M855. With a preference for LC.  No wolf unless I want to run malfunction drills


I run only mil spec ammo and reload to mil spec with H335 verified over a Ohler Chrono

Koot, yes, the back pressure created by the can increases the gas pressure immensely.  That really over gasses the bolt and slams the hell out of it if it is not moderated in any way.  It also fouls everything including the mag.  Thtas why some of the Spec Ops designated marksmen rifles have a switch block with two settings.

Thats the first buffer spring I've ever worn out and its soley because the weapon has been run exclusively suppressed for about 5000-7000 rounds.

http://www.syracordnance.com/collections/gas-blocks/products/gen-ii-750-adjustable-low-pro-solid-gas-block

http://slrrifleworks.com/index.php?route=product/product&path=57&product_id=582

Probably give one of these a try
Learn the rules like a pro so that you can break them like an artist -Pablo Picasso-

Offline OldKooT

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Re: Perplexed with FTF malfunction
« Reply #22 on: April 02, 2016, 08:15:07 PM »
I was just curious, I was going to build a suppressed .458socom AR, but the more I think about it, the more I suspect I will build a .458socom bolt gun to suppress instead. Sub sonic .458 can be quiet, and the same rifle can easily shoot much hotter rounds than the AR can handle, thus being a bit more rounded. Also, I can't drag a AR into Canada, I can a bolt gun.

I have noticed my AR seems to for some reason run a lot cleaner than some I shoot with. I have no explanation for this, as I use cheap ammo per my requirements LoL And so far, it will cycle anything I have tossed through it. I have noticed the guys who have suppressors seem to worry a lot more about the rounds they use. They seem to have cycle issues if they don't.

Norm

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Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #23 on: April 02, 2016, 08:57:13 PM »
Norm suppressed weapons should run anything because more pressure is pushed to the bolt carrier.  Suppressed guys that start fiddling with the gas pressure find that lower power ammo or when they remove the suppressor there is not enough power to cycle the weapon.

.458 SOCOM AR suppressed would be awesome.  Do it.
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Offline KensAuto

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Re: Perplexed with FTF malfunction
« Reply #24 on: April 02, 2016, 09:31:55 PM »

.458 SOCOM AR suppressed would be awesome.  Do it.

Yesss!!!!!
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Offline OldKooT

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Re: Perplexed with FTF malfunction
« Reply #25 on: April 03, 2016, 07:15:35 AM »
I may build both... I have two 24" 1/14 twist stainless .458 barrels in the raw. My machinist buddy has the throat reamer and other required tooling. In fact, I think the only thing I'd need to score is the head space gauges and another upper. Oh, and I suppose a bolt carrier group. Then obviously a suppressor....

I also have a Savage Model 10 .308 that's needing a overhaul anyway. Since I have multiple other .308's it could certainly lend it's self to a .458 socom bolt build. ..I really need to build a truck or two, so I guess I am in no hurry to build yet more weapons, maybe a winter project.
Norm

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Offline stlaser

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Re: Perplexed with FTF malfunction
« Reply #26 on: April 18, 2016, 05:08:13 PM »
Seven is six & six is five

http://weaponsman.com/?p=31194

TRN, saw this and thought of your high round count on this gun.....
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Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #27 on: April 22, 2016, 10:34:47 PM »
Update.  Threw a new buffer spring in it and it works like a champ.  I have an H1 buffer I'll throw in tomorrow and order an adjustable gas block.  The bolt is just beating the spring to death suppressed.  I need to bleed some gas off
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Offline BobbyB

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Re: Perplexed with FTF malfunction
« Reply #28 on: April 23, 2016, 03:43:46 PM »
Update.  Threw a new buffer spring in it and it works like a champ.  I have an H1 buffer I'll throw in tomorrow and order an adjustable gas block.  The bolt is just beating the spring to death suppressed.  I need to bleed some gas off

Thought you already had an adjustable GB. 
« Last Edit: May 13, 2016, 10:57:38 PM by BobbyB »
So, Bobby...being the calculating trained warrior NCO that you are.  Take the appropriate action, Execute!

Offline JR

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Re: Perplexed with FTF malfunction
« Reply #29 on: April 23, 2016, 03:59:38 PM »
Maybe you can open the gas port a touch and add a heavy buffer. They even make em with a piston in them to soften things up.

Major thing is it works now, fine tuning is not a bad thing.
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Offline stlaser

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Re: Perplexed with FTF malfunction
« Reply #30 on: April 23, 2016, 04:52:02 PM »
Why open up the gas port JR? The suppressor already has it over gassed, the heavy buffer just helps slow things down a little. I'm not opposed to the heavy buffer especially if he runs an adjustable gas block then I think he has best setup possible as far as a gassed system.
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Offline JR

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Re: Perplexed with FTF malfunction
« Reply #31 on: April 23, 2016, 08:16:00 PM »
Your right it needs to get closed if anything. Adjustable port would be better.
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Offline BobbyB

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Re: Perplexed with FTF malfunction
« Reply #32 on: May 13, 2016, 12:26:42 PM »
How's it working? Get it all fixed yet?
So, Bobby...being the calculating trained warrior NCO that you are.  Take the appropriate action, Execute!

Offline TexasRedNeck

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Re: Perplexed with FTF malfunction
« Reply #33 on: May 13, 2016, 07:40:37 PM »
No. I threw it in the safe and pulled out another one. I believe it is the giessele trigger set to light on the second stage and it's causing it to double and triple then bolt override. I'll get to it at some point.


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Offline BobbyB

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Re: Perplexed with FTF malfunction
« Reply #34 on: May 13, 2016, 10:57:11 PM »
No. I threw it in the safe and pulled out another one. I believe it is the giessele trigger set to light on the second stage and it's causing it to double and triple then bolt override. I'll get to it at some point.


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Well that'll do it as well. Just throw an ALG Defense QMS trigger in there.
« Last Edit: May 13, 2016, 10:59:08 PM by BobbyB »
So, Bobby...being the calculating trained warrior NCO that you are.  Take the appropriate action, Execute!