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Installing the JP VTAC FFT aka "How Bibliophobia can make your life exciting!"


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Magpul will take those Pmags right back from you and send you new ones right away.  You're damn good at explaining things technically, so they won't have a single issue with the swap.  Definitely worth doing, and it wouldn't be worth hanging onto those particular ones if they'll only work in one of your .308s.  Git 'em!  ;D

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As far as the Pmags , I will give them another chance this week end when I do some target work .

I found on post , test fire inspection -

- bolt catch pin was broke at the threaded part . Cracked almost in half ,with a large chunk missing & backed out to the end of the threads on the receiver ( probably was loose in there )

-Castle nut on receiver extension was loose. I need to strake it .

Any of these could cause malfunctions.

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Just ordered two bolt stop pin screws from SI Defence ,which are made from stainless steel , for $12.00 apiece with $14.67 shipping. You would think they could send it by snail mail cheaper!  Just crazy.

They are in the 308 upper , parts section ,why I don't know. I didn't take it out of the upper receiver.

I read some of the reviews of the DPMS ones in Midway & there's two reviews that say they broke .

Should I be putting this in the " 308 Build section " ?

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I've seen those same two reviews of the DPMS pins breaking, man.  I didn't even know SI Defense made better ones, so I'm glad you found those!  ;D  I'll probably pick up a couple just to have in the range bag.  Good info.  <thumbsup>

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Just ordered two bolt stop pin screws from SI Defence ,which are made from stainless steel , for $12.00 apiece with $14.67 shipping. You would think they could send it by snail mail cheaper!  Just crazy.

They are in the 308 upper , parts section ,why I don't know. I didn't take it out of the upper receiver.

I read some of the reviews of the DPMS ones in Midway & there's two reviews that say they broke .

Should I be putting this in the " 308 Build section " ?

Might be worthy of its own topic for sure

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  • 6 months later...
  • 3 weeks later...

It's funny Im doing my second one of these and just had an issue which Ill get to later. Curiously Matt you mentioned a few times that the receiver nut was hard to turn. I think that was most likely due to the loctite from the previous FFHG. On my current VTAC as well as the one prior the nut spins very easy.

My barrel nut aligns with the gas tube hole around 3pm. I will be using the 271 Loctite per the instructions.  Loctite was my "issue". I couldnt find my 271 but i had a sample of Loctite "Red" Gel. After 24 hours it didnt cure the slightest. What a pain cleaning that crap off.

BTW I use a piece of drill rod the exact size of the gas tube hole in the receiver. I plan on making a stepped unit for times when the hole in the nut is larger than the receiver hole.

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It's funny Im doing my second one of these and just had an issue which Ill get to later. Curiously Matt you mentioned a few times that the receiver nut was hard to turn. I think that was most likely due to the loctite from the previous FFHG. On my current VTAC as well as the one prior the nut spins very easy.

My barrel nut aligns with the gas tube hole around 3pm. I will be using the 271 Loctite per the instructions.  Loctite was my "issue". I couldnt find my 271 but i had a sample of Loctite "Red" Gel. After 24 hours it didnt cure the slightest. What a pain cleaning that crap off.

BTW I use a piece of drill rod the exact size of the gas tube hole in the receiver. I plan on making a stepped unit for times when the hole in the nut is larger than the receiver hole.

You're exactly right about the loctite, but I wasn't really so much suprised as pleased, I was thinking that a rail might one day adorn the top of the FFT and I didn't want that sucker moving around on me anyways...

My biggest concern was with whether or not I was going to bind the nut while tightening it and then be unable to get it back off without marring it, aluminum threads can be a bit fickle when mated to a harder metal.

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  • 1 year later...

My biggest concern was with whether or not I was going to bind the nut while tightening it and then be unable to get it back off without marring it, aluminum threads can be a bit fickle when mated to a harder metal.

Use (any kind of) the proper lube during assembly, and this is not a problem, in the least. 

None.

Assemble it dry, and you will have a problem.  You'll feel it when you're trying to tighten it - sounds like that's what happened with you, Matt, considering your description of the events that took place.  Lube the barrel nut and the threads on the upper receiver...

Aluminum threads on the upper and a steel barrel nut shouldn't be any problem at all.  None.  <dontknow>

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Use (any kind of) the proper lube during assembly, and this is not a problem, in the least. 

None.

Assemble it dry, and you will have a problem.  You'll feel it when you're trying to tighten it - sounds like that's what happened with you, Matt, considering your description of the events that took place.  Lube the barrel nut and the threads on the upper receiver...

Aluminum threads on the upper and a steel barrel nut shouldn't be any problem at all.  None.  <dontknow>

You're definitely right about that. That's what happens when you chunk the manual and say "How hard can it be?". To anyone who might be coming back to read these old threads, do yourself a favor and prelube your threads, it'll make your life easier.

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  • 3 weeks later...

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