A.R.M.S. #41 B-L Should I or Shouldn't I?

[Vic 103]

I got a A.R.M.S. #41 B-L A2 folding front sight and I'm sitting here thinking should I or shoulden't I install it now.

Does anyone here have one of these? It will work perfect with my Eotech. It folds down just enough to be out of the way of my sight window.

I had my new Sport (not even a week old) on the range yesterday and ran a hundred rounds through it (whithout the Eotech) and it performed perfect (I love this rifle) It was sooooo accurate.

I'm thinking now would be a good time to install it, before the gas block gets all carbon locked up.

I know it's barrel mounted with cap screws, but I figure once I sight it in and I am happy with it I can run one taper pin on top of the barrel in the front post only. This should be just as good as the standard two taper pins on the bottom of the barrel, and where I work I have access to just about every type of loctite they make (for the screws)

Just wondering if anybody here has one of these or knows sombody that has one and what they think of it.

Thanks for your help.

 

[oneyeopn]

I would eventually like to get one, I replaced my gas block after about 800 rounds of steel (russian) ammo and another 300 of federal xm193 and didnt have a problem getting it off. My new gas block has two set screws from the bottom and it doesnt move at all. IMHO drilling for a taper pin would honestly be overkill but it is your rifle and you make the decisions. Let us know how it works though. I seriously thought about it but bought a railed gas block and an AXC folding front sight off of eBay instead. Spent about $50, but that sight looks sweet in pics and in the catalogs.

 

[ZeroTolerance6]

Since you have it, do it now. Like Grover, I put hundreds of dirty russian rounds through the barrel and was still able to remove the factory A2 with no issues at all. Just make sure you drive the pins out the correct way. As I recall, right to left. There are other posts on this forum about how to get the stock GB off, searching will give you detailed instructions.
Best of luck.
Once done, would love to see pictures of it.
ZT6

 

[Vic 103]

Ok guys thanks for the kick in the a** that I needed.

Everything came off nice, pins were a little tight, needed a good smack.

My iron sights were pretty good when I went to the range (I didn't take Eotech with me on that trip), I wanted to see how rifle functioned and work on ironsights. But when I got home I put on the Eotech and co-witnessed it to my iron sights. So then when I mounted the A.R.M.S. #41 B-L, I used th Eotech to align it. Don't know if this will work but it is worth a try.

All Done!!

Folded:

Open:

Now all that's left is to go to the range and make sure I don't have a one shot wonder, sight in the irons, pin it and loctite it. Then I will finally get to play with my Eotech. This kind of work is fun!!

 

[oneyeopn]

Vic I really like the way that sight looks on your rifle and congrats for getting it done.

 

[Vic 103]

Oh man, I just got back from the range. Put another 100 rounds through it and it performed flawlessly. I love that A.R.M.S. #41 B-L front sight post. The windage was right on. I just had to move the elevation about 3 clicks. My main concern was windage. That looks perfect. So sometime this week I'm gonna take it to work set it up on my Bridgeport and put in the tapered pin. I know you said this was overkill oneyeopn, but it's just for my own peice of mind. This way I know it will never move.

While I was there I noticed my LGS is stocking more and more AR parts. I looked in the locked glass case and he had one of these:

OMG I've been looking at these on line lately, and there it was right before my very eyes. Full auto version. Dam the EBR!

 

[oneyeopn]

Yeah I want one of those also....real bad LOL

 

[BillyJack2012]

What a great looking front sight and alternative to the fixed! Great, functional add!

 

[Vic 103]

Just a little update/side note. Before trying to pin the ARMS sight, I figured I'd do a little research about the melonite treated barrel and I found out that the Rockwell hardness inside the bore and outside the barrel is roughly (I got numbers between 64 and 70) which is very very hard. Heck, a die trim steel (heat treated steel details which are used to stamp out thousands of parts steel production parts) is usually hardened to 60-62.

So I would have no chance in hell of drilling a tapered pin hole into the barrel. The drill would just veir off make a crocked hole or break wrecking the sight. Thank god I did not try this.

Reading up on this melonite process makes me see how bad a** these melonite barrels really are. So glad I got a Sport

Anyway I have to just settle with loctiteing the screws. I used this:

This is what you need for high tempeture applications.

 

[Vic 103]

Update number 2.....heh

It has been driving me crazy not having this front sight pinned in place. It is set perfect and i don't want it to move at all. So I decided to use the existing holes in the barrel from the orginal sight. I checked it out with my height gage. I knew the pins would be close to the screw head on the counterbored side but it would definitely miss it.

Here is a picture of my barrel when I orginaly removed the factory sight. You can see the 2 pin holes in the barrel:

First I had to make a holding block. To hold the upper assmbely. So I made it out of a block of nylon. Here's my crapy sketch:

Then I had to map out the holes. Since I could not remove the sight to just check the location in the barrel. I used the orginal sight, pins, and a pair of calipers to measure where the holes are. And I came up with this sketch. The boxed dimemsions are the numbers I had to hit. As you can see these dimemsions are not a standard. Probably all sight pins are slightly different.

My hole map:

Now I set the barrel up on the Bridgeport. I indicated it in with my indicator to make sure the barrel was zeroed out:

I used the machines digital readout to go to my numbers. The sight is curved right where the holes have to go. So I used a 1/8th end mill to create a flat in that area. I then used a small center drill to spot the area where the drill has to start.

1/8th end mill flat:

Next I drilled the holes. First I went with a .090 drill and then a .120 drill. I was sweating bullets at this time praying that my calculations were right. I knew even if the vector was off a little that was ok because the drill would follow the hardened barrel. That is why I went with smaller drills. The tapered hole on the small end had to finish at .126 and the large end had to finish at .140 So I used the smaller drills and then reamed by hand with my tapered reamer. And again the reamer just followed the hardened barrel making the hole a prefect taper. The reamer cut the sight to match the existing holes.

Drill hit the holes.........Yippie:

Then I just reamed by hand until I got the desired fit. The barrel is hard but the sight is soft so the reamer aligned itself. I pounded the pins in and all is good!!

It worked...........Yippie dippy doo!!

I will now close this subject. I'll bet you guys are glad of that hehe.

 

[Andrew911tt]

Great Job!

 

[cyphertext]

Love the look of that sight. And wow!...the effort you put into making it perfect.

 

[Chaos6]

Hello Vic,

Could you please tell us if the hight on this sight matches the "F" marked FSB or non "F" Marked FSB.

I need the extra height of the "F" Type FSB so before I spend the dough I need to know.

 

[Vic 103]

After measuring I'm pretty sure it is a non "F". Also there is no "F" stamped on the sight. I know after mounting it when I went back to the range I had to move my front post 3 clicks to hit like I was hitting before with the orginal factory sight which is marked "F". This is at 25 meters. The post flange is still slightly below flush.

After I saw your reply I did some searching and I found this:
Help Identifying my front iron base... - AR15.Com Mobile It was kinda interesting.

 

[Chaos6]

Yeah Vic, I read all about that on AR15.com because I do not have a "F" Markded FSB and so the base of my front site post is up above the shelf of the FSB and actually a little wobbly.

So you took measurement on this one and got the 1.94 from the barrel to the shelf instead of 1.98?

I dont really want to go the cheap route and buy a taller post because I want to use the hooded cross hair post I have, its much more accurate IMO.

Thus I have been searching for an option to replace my FSB without having to do any drilling. There are other folding front sites with gas blocks that say they are "F" height but I really did like this one and was hoping it would be the right height.

 

[Vic 103]

So you took measurement on this one and got the 1.94 from the barrel to the shelf instead of 1.98?

Yes that is correct.