I was curious about the FNC bolt carriers and bolts and possibly different versions. I am hoping Paco or some others have the info as well as some good photos. Do we know how many different versions of the FNC bolt carriers and bolts there were? I'm interested in early vs. later models primarily, semi vs select fire, not necessarily FNC vs Pindad models. And could the bolt from one version carrier be dropped in and used in another without modifications.
FNC bolt differences
- Thread starter dubagel
- Start date
TheColtCollector
UZI Talk Life Member
Deleted. I was wrong lol
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Paco will be around shortly, I'm sure... with many pictures and a wealth of knowledge.
I will comment on one aspect, the interchangeability of FNC bolts. Unfortunately they are NOT like an AR15 bolt, where you can move them from rifle to rifle and not worry, too much about headspace. The FNC is headspaced during the barrel install. At the factory, the barrel is installed and the barrel is either tightened or loosened into the receiver/trunnion, against the bolt, to achieve proper headspace. Once headspace is obtained, the barrel lock nut is tightened down against the trunnion to maintain headspace. At this point, the gas port is drilled and the front sight/gas block is installed. From this point on, the bolt is married to the specific receiver/barrel combination. This is one of the main reasons when Green Mountain manufactured the FNC replacement barrels, that they didn't drill the gas port in the barrels.
Don't get me wrong, having a spare FNC bolt is a good thing! If you're lucky, the bolt will headspace, very few do... However, adjustments can be made to achieve headspacing. It's not ideal, but its do-able. Material can be removed from the bolt, if headspacing is too tight. The barrel can be adjusted in/out of the trunnion, but you'd have to move the gas port, fill the old gas port and drill a new one in your existing used barrel. Likely the best solution would be to have a virgin Green Mountain barrel properly installed, headspaced to your replacement bolt and have the gas port drilled.
Thanks for the info Fuatos!! I was looking and thinking about those same things and scratching my head when I pulled the toy out of the safe yesterday. Lol. From a military support and logistics and manufacturing point of view, that really sounds like a real shortcoming of the FNC. I've had my semi-auto Fnc para since 1989. Low miles on it, about 2500ish rounds with good ammo and haven't shot it in a few years. Wanted to go shoot it. Have extra firing pin and recoil springs, so not really concerned about anything else on it. Lately about the only thing that really concerns me is the bolt. I was even going to see if the fn m249 SAW bolt was similar or able to be modified.
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There are many variants out there.
Don't brake it ; )
If you can find a spare, BUY IT!
Best investment ever.
Last one i spotted in Belgium (like 7 years ago) was 500$
Don't count on Belgian Army FNC's, they will be shredded under supervision including the spareparts.
Sweden is even worse and Pindad sucks unless you got 100K or so
Paco
Don't brake it ; )
If you can find a spare, BUY IT!
Best investment ever.
Last one i spotted in Belgium (like 7 years ago) was 500$
Don't count on Belgian Army FNC's, they will be shredded under supervision including the spareparts.
Sweden is even worse and Pindad sucks unless you got 100K or so
Paco
Paco, are those bolts and carriers interchangeable between each carrier and visa versa or are they specific to the "generation" like early bolt must go with early carrier, not latest bolt with early carrier? If I email some pics of my bolt can you tell what "generation" it is and what kind of shape it's in? Isn't the m249 SAW/Minimi bolt similar, there is now a semi-auto m249, I'd like to compare them side by side.
Excellent info in this thread. I assumed the bolts could simply be replaced. Makes sence they have to be checked, as this design is similar to the AK where headspace must always be addressed when swapping bolts.
Makes you wonder how many people have blown firearms up due to not checking this after a bolt change.
Makes you wonder how many people have blown firearms up due to not checking this after a bolt change.
Hi
The M249 bolt is not an option.
Yes i can ID your bolt if you got HD pics.
Yes there are 5 types carriers around. The latest 3 are interchangable.
Carriers are tended to brake at there welding near the tube. The latest generation has fortified extra weldings on it.
They (carriers in general) are also a pain in the ass to locate any.
Paco
The M249 bolt is not an option.
Yes i can ID your bolt if you got HD pics.
Yes there are 5 types carriers around. The latest 3 are interchangable.
Carriers are tended to brake at there welding near the tube. The latest generation has fortified extra weldings on it.
They (carriers in general) are also a pain in the ass to locate any.
Paco
mad scientist
Well-known member
- Joined
- Aug 19, 2013
- Messages
- 112
Very interesting discussion, thanks paco.
I am curious...this gunbroker listing describes the carrier as "modified to auto configuration". Is this something that need to be done, or is this simply internet auction bullshit? I am curious so that I can check my bolt carrier if needed.
http://www.gunbroker.com/item/637531421
I am curious...this gunbroker listing describes the carrier as "modified to auto configuration". Is this something that need to be done, or is this simply internet auction bullshit? I am curious so that I can check my bolt carrier if needed.
http://www.gunbroker.com/item/637531421
The bolt carrier will be modified by having the trip installed that releases the auto sear when the carrier is forward and the bolt is locked. Basically that part of the auto sear conversion is complete.
The carriers with 3 welds are the best.
On the left side you will see that the old carriers had only 1 weld.
Then they made 2 welds on top (piston) and later they made a 3th weld in the middle.
In the picture
on top=3 welds
middle = 2welds
lower= 1 welding
On the left side you will see that the old carriers had only 1 weld.
Then they made 2 welds on top (piston) and later they made a 3th weld in the middle.
In the picture
on top=3 welds
middle = 2welds
lower= 1 welding
PACO is it possible to go back and put additional welding if I have a rifle with one or two Welds? They all appear to be the same bolt carrier anyway. Is this something Okpud could do. To be honest some of the welds look as if I did it, very amateurish
okpud
UZI Talk Supporter
I've welded up a few in the past, usually combined with other work. What I tell most customers it to look for any cracks on the welds when cleaning the rifle. No cracks = no problem. If you start to see a crack forming on a weld, then it's probably time to do something about it. Out of the dozens of FNC I've worked on (can't remember how many anymore), most only had the single weld. Only 2 (3 if you count mine) had a crack starting to form.
A lot of the welds will look sloppy because of the how thin the piston rod is. You can't weld too hot or you can damage it. You also need to make a good heat sink to go in the tube for welding. My general rule of tube for weld like this (internal welds no one sees under normal conditions) is to go for strength over cosmetics. Sure, you could grind them down and polish them up, but why? It would only make the weld weaker for the sake of making it look better.
Yes it is. Technical maintnance manual for armorers. Both Dutch/French in one book.
Very rare, they are "protected". Theoreticly, you can't have one ; )
Very good data and pics to install every single part. gauges, go-nogo...
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