FN 15 Tactical series...pinned gas blocks?

[Biggy]

For LPGB’s I prefer coil pins, not a roll or straight or tapered solid pins. As it has been said many times before and has been proven beyond any doubt, properly installed set screws will hold just fine. Use the correct knurled tipped set screws on a dimpled barrel, prep the screws and use either red locktite or Rocksett if you must and lightly snug the screws so the knurling bites in.
I like LPGB's that use coil pins because in my experience their removal is usually easier than set screws that have had a high strength thread locker used on them. But then again, how often are you ever going to remove the gas block.

[RJflyer]

The original FN 15 Tactical MLOK had a screwed on gas block. The newer Tactical II model (36312-01) has a pinned gas block.

I guess I'll elaborate on my experience FWIW. I have both the FN15 Tactical Carbine (36313) and FN15 Tactical Carbine II (36312-01). Both have low profile gas blocks. The Tactical Carbine's is retained with two Allen screws at six o'clock. The Tactical Carbine II's is retained with a single, large solid pin.

After seeing this thread I decided to see if my Tactical Carbine was dimpled for the gas block's Allen screws...it wasn't. As a matter of fact it took surprisingly little effort to unscrew the Allen screws. I couldn't see any sign of loctite or rocksett on the screws. This was a bit concerning to me, however, it never gave me any issues when firing the gun. Caveats: obviously this is only a sample of one; also I haven't run this gun particularly hard.

I'm not posting this to make an assertion that pinned gas blocks are inherently better than set screws. I'm simply posting my experience for the OP and anyone else who might be trying to decide between these two models. Personally, I have greater peace of mind with my Tactical Carbine II's gas block. Whether that's truly warranted or not...you can decide.

[26 Inf]

There was recently a pretty long discussions about this subject on here.

I think we see a lot of manufacturer/employee loyalty in these debates - as might be expected.

It seems to me that the front sight tower on the mil-spec weapons needed to be cross pinned rather than set screwed because of torsional forces to which the assembly was likely to be subjected. Not very many of us attach bayonets to our low profile gas blocks.

Pinning gas blocks takes more manufacturing time and equipment than does set screwing gasblocks. If you are, for example, SIONICS or BCM, you spec your barrels dimpled for the rear most set screw.

If you are a minimalist builder you have a split point carbide bit and a drill to dimple them yourself (unless you are buying pre-dimpled barrels).

It isn't rocket science and most folks can do the job in 5 minutes or less. The result is a gas block that will, in all likelihood, stay in place for the life of the rifle.

You'll note I said in all likelihood. That is because vibration is the enemy of the set screw, especially if you aren't using the right point on your set screw, or, if you screw up the threadlocker application. Why do you think critical components on aircraft are safety wired? If it is threaded it can vibrate loose.

Using a spring pin or a coiled spring pin eliminates that concern. The primary drawback to using a spring pin is that you need a drill press or mill, or, you have to pay someone to do the job for you.

To summarize - set screws = adequate; spring pin = bombproof.

Two things that I find interesting and humorous about this deal are 1) that folks who are normally all about the 'mil-spec' are suddenly a lot more flexible when their sacred cow deviates from the mil-spec; and 2) a signficant numbers of a group of guys who discuss going armed at all times, just in case, are willing to accept anything but and absolute installation of a key component of their rifles gas system.

FWIW, I generally use Geissele gas blocks and pin them; if I use another brand gas block, unless it is set up to be pinned, as are the Geissele's, they are just set-screwed.