Gas block with flip up sight?

[Skyfire1201]

I'm thinking of building a new 18" SPR type rifle, and instead of mounting the front BUIS to the rail, I'm considering getting a gas block with built-in flip up sight. I found several, but none of them seem to fit the categories I'm looking for:
- Has to LOCK in the UP position (like Troy flip up irons)
- Regular M4 style front, not the HK round kind
- Light weight (or at least close to the normal M4 front sight in terms of weight)

Does anyone know of one that fits my requirements? Colt seem to have one on their 6940, but I can't seem to find anywhere that sells it as a spare part.

Thanks in advance!

[ColtSeavers]

ARMS #41 BL

http://www.brownells.com/rifle-parts/sights/front-sights/ar-15-m16-41-bl-silhouette-folding-front-sight-prod26728.aspx

http://www.brownells.com/userdocs/products/p_100003742_1.jpg
http://www.brownells.com/userdocs/products/p_100003742_3.jpg


Have had mine for years, has never failed, never loosened, still locks up, still would get another in a heartbeat if I was to build or rebuild an AR with a rail shorter than the gas journal.

[Skyfire1201]

Thanks ColtSeavers! I saw the ARMS unit but wasn't sure how it actually locks up? Or more importantly, is it a positive detent type lock, where you have to press a button to set it down? Roughly how much does it weigh?

[ColtSeavers]

It does not truly lock in either position, but due the the angle and spring pressure of the extendable angled support arm it is does not fold down unless one presses directly down just behind the sight post/ears on the joint on top of the extendable angled support arm. If that makes sense.

I honestly do not know what the weight is, but due to that material and all-in-one folding front sight gas block design, it is not lightweight. However, due to it's design and functions as previously mentioned, it should therefore be compared to either an A2 FSGB or both a folding front sight's and a gas block's weights combined.

ETA: If I absolutely had to make a guess about how much it weighs right now, I would put my money on the same weight as an A2 FSGB.

[sig1473]

ARMS #41 BL

http://www.brownells.com/rifle-parts/sights/front-sights/ar-15-m16-41-bl-silhouette-folding-front-sight-prod26728.aspx


Have had mine for years, has never failed, never loosened, still locks up, still would get another in a heartbeat if I was to build or rebuild an AR with a rail shorter than the gas journal.

I have an ARMS 41 as well but without the bayo lug. My experiences mirror yours as well. Very robust part and has never failed. I still prefer pinned FSB but I'm not dragging it through the mud. The only weakness/flaw in these are the hex screws which seem to be easily rounded if too much torque is applied when tightening. I've contacted ARMS and they sell replacements. I wouldn't hesitate to purchase another but the price for them is kind of salty(~$150).

[misfit47]

Yhm has one as well.

[Eurodriver]

Why does the front sight need to fold?

[ColtSeavers]

Why does the front sight need to fold?

Some people dislike having the front sight's silhouette in their sight picture when not using irons.

[^Rb]

https://www.vltor.com/shop/front-sight-towers/vst-clamp-on-front-sight-tower/

[Skyfire1201]

Does the Vltor sight lock when its up?

[AKIA_AZ]

Does the Vltor sight lock when its up?

According to the Vltor website, no it does not lock.

[Gunfixr]

I have a lightweight rifle I built for my wife/daughter to shoot, and it has the yhm folding sight gas block on it.
It is light (skipped the bayo lug).
It is similar to AR front, ears, not round.
It does lock in the up position, using a side push button release, like a buis.
All steel.

I'm normally not a fan of clamp on gas blocks, I'm sure I don't need to say why here. So, I set a dowel pin into the top of the barrel, that goes into a matching hole in the gas block, to lock it in place. This gives the added benefit of being able to remove it, and place it exactly back where it was, should some reason ever occur.

Sent from my SGP612 using Tapatalk

[Kadelic]

Rock River Arms makes one that seems to fit the bill.

40541

Here's a link to the website: https://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_id=323

I happen to have one I'm not using. I took it off my RRA rifle when I replaced the rail. I removed the sling swivels. If you're interested I'll dig it out and take some pics.

[misfit47]

That's a yhm isn't it?

[Kadelic]

That's a yhm isn't it?

I'm not 100% sure, but a few websites have them listed as RRA parts.

[Stickman]

- Has to LOCK in the UP position (like Troy flip up irons)
- Regular M4 style front, not the HK round kind
- Light weight (or at least close to the normal M4 front sight in terms of weight)



The ARMS 41b locks in the upright position.

The Vltor is very nice, but does not lock upright.

All the YHM ones I've seen have had a habit of coming loose, even with thread lockers.

[Renegade04]

Yhm has one as well.

I like the YHM. I used one on a Dissipator I did a few years ago.

http://i100.photobucket.com/albums/m8/jamesrea_2006/jamesrea%202012/019_zpscc264941.jpg (http://s100.photobucket.com/user/jamesrea_2006/media/jamesrea%202012/019_zpscc264941.jpg.html)

http://yhm.net/front-flip-sight-tower-standard.html

[ColtSeavers]

The ARMS 41b locks in the upright position.

This is not quite accurate. It has a detent that helps keep it in place in the up/deployed position, like the safety selector, but not a true push button locking detent/mechanism like a Troy BUIS as the OP described.

Again though, I have never been able to intentionally or unintentionally make it collapse without applying pressure directly down on the angled support arm joist as intended by manufacture, and have not read of others being able to do so either.