How to I mount this FSB?

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[ARCHIVED THREAD] - How to I mount this FSB?

Posted: 3/17/2012 4:02:57 PM EDT

With a screw on the bottom or something?

This barrel is not drilled for taper pins, I guess.

Thanks,

Posted: 3/17/2012 4:50:23 PM EDT

[#1]

Is hat hole threaded for a set screw?

Posted: 3/17/2012 5:05:34 PM EDT

[#2]

double

Posted: 3/17/2012 5:06:44 PM EDT

[#3]

Quoted:

Quoted:
With a screw on the bottom or something?

This barrel is not drilled for taper pins, I guess.

http://i40.tinypic.com/359xx8j.jpg http://i44.tinypic.com/1073lm9.jpg

Thanks,

No.
You don't want to install that FSB yourself.
That is a virgin FSB. It needs to be drilled to your barrel by a Black Rifle qualified 'smith and then taper pinned.
Not a home project.

Send the barrel and FSB to ADCO and have them pin it for you.

Posted: 3/17/2012 5:38:25 PM EDT

[#4]

Somehow managed to miss this important fact when researching all of this...

What are my other options then?

Thanks,

Posted: 3/17/2012 5:48:15 PM EDT

[#5]

Bravo sells a jig.

Here are the instructions.

http://www.brdengineering.com/uploads/How_to_use_the_BRDE_FSB_alignment_jig.pdf

Posted: 3/17/2012 6:00:01 PM EDT

[#6]

As it was explained to me, the FSB is one of the precision fitted parts that must be done correctly for the rifle to function properly. I ended up just buying a complete upper.

Posted: 3/17/2012 6:16:01 PM EDT

[#7]

Quoted:
http://i44.tinypic.com/3479tte.png

Somehow managed to miss this important fact when researching all of this...

What are my other options then?

Thanks,

Are you set on an A-frame FSB ?

Posted: 3/17/2012 6:24:46 PM EDT

[#8]

I figured it would be the most rugged option.

Also thought it would be the most economical!

Posted: 3/17/2012 6:25:38 PM EDT

[#9]

+1 on sending it to ADCO. If you don't want to do that then this is another option:

Armalight clamp-on FSB

Posted: 3/17/2012 6:30:35 PM EDT

[#10]

Adco's site reads, "We do NOT install FSBs on any surface coated/hardened barrel."

This barrel is melonite treated. Does that mean they wouldn't work on it?

How rugged is the Armalite clamp-on fsb? The price sure is appealing...

Posted: 3/17/2012 6:32:27 PM EDT

[#11]

Quoted:
+1 on sending it to ADCO. If you don't want to do that then this is another option:

Armalight clamp-on FSB

This.
These are the options and the Armalite may not be F-height.

Don't use a set screwed FSB unless the barrel is prepped with machined "flats".

Posted: 3/17/2012 6:32:46 PM EDT

[#12]

And how does the Armalite clamp-on stay centered?

Posted: 3/17/2012 6:37:23 PM EDT

[#13]

Quoted:
Adco's site reads, "We do NOT install FSBs on any surface coated/hardened barrel."
This barrel is melonite treated. Does that mean they wouldn't work on it?

I would email ADCO...they don't do phone.

How rugged is the Armalite clamp-on fsb? The price sure is appealing...

Nowhere near as rugged as pinned.
Pinned is combat proven. You can hang a bayonet on it.
For a hobby gun clamp-on is OK. If the FSB spins you instantly loose your gas system and are relegated to a single shot.

Posted: 3/18/2012 6:37:27 AM EDT

[#14]

OK there have been many threads with both sides of the issue voiced about clamp on FSB's. A couple of the people that say they are OK have had high post counts and actually may be people that build rifles for a living. People that have been doing competitions swear by the clamp on as well. Yes the pinned FSB's do have a greater mechanical advatage. I would also like to see what it would take to spin a clamp on style FSB properly installed.

The Bayonet comment did make me chuckle ( no offense intended).... if you are down to bayoneting someone you are already in a bad way anyway. People say they are silent.... no they are only as quiet as the person screaming as you are doing it.

Posted: 3/18/2012 8:06:41 AM EDT

[#15]

Quoted:
And how does the Armalite clamp-on stay centered?

The sight does not have a set pin, it relies wholly on clamping force. One of the reasons why I like the system is because of this very fact, you can set your windage dead center on the rear sight and then move the fsb so you never have this if the FSB was pinned a little off:

As for strength I use brake cleaner and then rocksett on them, I would bet that other parts of the rifle would be damaged before the FSB moves.

Posted: 3/18/2012 9:29:25 AM EDT

[#16]

Quoted:
The Bayonet comment did make me chuckle.....

Pull yer head out....this was only meant as a way to describe the difference in strength between bolt-on and pin-on.
That difference is why professional weapons use pin on....not for bayonets patricularly, but for the ability to withstand rough service.
Pinned on FSB's make it possible for us to have this happy banter.

The clamp on FSB is a hobby part.
The set screw FSB with machined flats is a competition part because it permits precise windage adjustments and is not required to endure rough service. Of the two bolt-ons this would be the hardest to move by design.

Posted: 3/18/2012 9:33:20 AM EDT

[#17]

Quoted:

Quoted:
Adco's site reads, "We do NOT install FSBs on any surface coated/hardened barrel."
This barrel is melonite treated. Does that mean they wouldn't work on it?

I would email ADCO...they don't do phone.

How rugged is the Armalite clamp-on fsb? The price sure is appealing...

Nowhere near as rugged as pinned.
Pinned is combat proven. You can hang a bayonet on it.
For a hobby gun clamp-on is OK. If the FSB spins you instantly loose your gas system and are relegated to a single shot.

I have made several hundred uppers over the last 20+ years and found that doing the pinned blocks is
cheaper, faster and easier if you have the correct tools.
Standard pinned FSB is but much cheaper than a clamp on and GI Joe cant screw it up with a wrench is why the military like them
more than just it wont move.

If the screws are are tight on a clamp on there is no fn way your going to spin the thing by smacking it on a rock or falling on it as I have tried with a scrap barrel
in a barrel vise and a hammer and it took a many whacks to get it to even move a little and when it did the
sight was beat to hell, your sight will be shit before it moves if it had a 10 floor drop off a building.
The set screw sight blocks will move easier for sure on battle grounds even with the flats.

Posted: 3/18/2012 9:41:17 AM EDT

[#18]

Quoted:
The set screw sight blocks will move easier for sure.

Set screws without machined flats are schitt (ghetto), I agree.
Have you ever tried to destroy a properly set screwed FSB with the machined flats as per a CMP rig ?

I have not, but it would seem to me that something would have to break before it would move.

Posted: 3/18/2012 10:51:47 AM EDT

[#19]

Direct sorry if you miss the (No offense intended). Just giving my 2 cents....

Posted: 3/18/2012 10:58:09 AM EDT

[#20]

Quoted:
Direct sorry if you miss the (No offense intended). Just giving my 2 cents....

Sorry as well for the flame.....

Posted: 3/18/2012 1:06:49 PM EDT

[#21]

Quoted:

Quoted:
The set screw sight blocks will move easier for sure.

Set screws without machined flats are schitt (ghetto), I agree.
Have you ever tried to destroy a properly set screwed FSB with the machined flats as per a CMP rig ?

I have not, but it would seem to me that something would have to break before it would move.

What sucks with the flats is you can smack the barrel with a hammer very few times and the block will move
left or right and the screws are known to come loose more because you can only wrench them
so much before they will strip.
Many of the good clamp on style blocks have more than two screws that are larger stronger and can put more pressure around the barrel so that makes
the clamp stronger than two screws that push.
Set screws only put pressure on two sides of the barrel, top and bottom
Deep dimples work better for a set screw block but you must have everything lined up good before you drill and then you
could still have the problem of the screws coming loose unless you use locktite.
I have a pistol that I shoot 500 grn to 900 grn pills with and I wanted a block around the barrel with a sling swivel just to use a bipod and sling
when hunting.
The damn block had 4 set screws that worked the same way as a gas block on a AR and I thought it would be fine until
I got 4 rounds down range and noticed the block had moved a bunch because of the recoil

I took the block off and got to see where the set screws had dug a trench in the barrel as the screws were harder steel than the barrel

After cleaning up the barrel on the lathe I made a clamp on block just for this gun and it has never moved.

Since then I have done some very harsh testing with set screw blocks and clamp on and i will never go back to set scews.

Posted: 3/18/2012 1:13:29 PM EDT

[#22]

I bought 2 used F marked FSB's off the EE that had the taper holes in them..

I used an 8/32 tap and 4 8-32 x 1/8" setscrews with 0 problems thus far..

Granted after I got them centered up.. I use my dremel with an end mill type bit and did some flat dimpling on the side where the setscrews would seat flat into.. I did 1 hole at a time with 3 screws always holding it centered..

My last one was only 5 clicks on the rear sight to the right to get it dead on..

The JIG is $150+ so for a 1x use would be silly IMHO and they recommend using a mill setup to use it properly..

I would suggest going with maybe the Armalite Clamp-On if ADCO can't/won't hook you up.. its just easier and should work fine unless your barrel is .625 vs the 'normal .750 where the gasblock seat is.. (The Armalite is .750)

ETA.. there is a tutorial on here somewhere on how to do what I did..

Posted: 3/18/2012 9:00:12 PM EDT

[#23]

Well, Adco and the other two places I checked with will not attempt it. The melonite treatment makes the surface metal too hard to drill. One of them did say that a good clamp-on will stay put if screwed-on tight enough.
So I think I am going to go with either the Armalite fsb mentioned above, or a flip-up one from YHM. Will report back here if I have any problems.

Thanks

Posted: 3/18/2012 9:10:55 PM EDT

[#24]

The Yankee Hill one (YHM9394) is a few bucks more, but uses 4 screws to hold it into place, versus 2 for the Armalite one. That's not to say that it is capable of being made to fit more tightly, but it should make it less likely to loosen up, I think.

Posted: 3/18/2012 9:25:41 PM EDT

[#25]

I used The Same YMH And It Was Rock Solid Just Use Red Locktite!

Posted: 3/18/2012 10:05:54 PM EDT

[#26]

your barrel does already appear dimpled for a set screw go with a low pro with set screws and then cover it up with a free float. I am surprised to hear of set screw gas blocks rotating especially if your barrel is dimpled seems like it would be tuff to do but then i don't have a giant a frame fsb.

Posted: 3/19/2012 1:20:45 AM EDT

[#27]

Quoted:
And how does the Armalite clamp-on stay centered?

this is what i do..

i take my rifle with a red dot sight.. i sight the red dot it at 25-200 meter target paper.

bring the rifle home(or do it at the range if they allow this), mount the front sight, and match the red dot to the front sight (twist and post level adjusted with real sight centered)

take it back to the range, make final adjustment on the front sight post and real sight(windage via real site, elevation via front post)

Posted: 3/19/2012 5:53:04 AM EDT

[#28]

If I don't have to spend the extra bucks for a free-float, then I'll stick with the MOE I bought, and try one of these clamp-ons. I can always swap for a free-float later if the clamp-on doesn't work out. Would an iron sight on top a rail be that much tougher anyway?

Posted: 3/19/2012 6:56:13 AM EDT

[#29]

Yhea for the cost, I would just get a low profile set screw gasblock, FF rail and magpul front flip up sight. Looking to do this with my 9mm carbine, minus the gas block of course.

Posted: 3/19/2012 7:15:21 AM EDT

[#30]

Quoted:
If I don't have to spend the extra bucks for a free-float, then I'll stick with the MOE I bought, and try one of these clamp-ons. I can always swap for a free-float later if the clamp-on doesn't work out. Would an iron sight on top a rail be that much tougher anyway?

If you already have the MOE get the Armalite clamp on.

Center your rear sight and dial the FSB position to that.

The only problem you may have is that this clamp-on may not be "F height"
so you may need a longer sight pin to compensate.

Good luck.