Fortis LW enhanced end plate and castle nut

[maximus83]

Put together a new lower and thought some might be interested in the Fortis end plate / castle nut. Fortis says the goal was to have a lightweight but strong end plate and castle nut combo that would making staking unnecessary, while improving on ratcheting solutions like PWS.

Here it is:
https://fortismfg.com/endplate-castlenut-k1

Details in the lower:
- Aero M4E1 receiver
- Sionics ambi LPK
- Sionics (Schmid/1005) 2-stage trigger
- Troy ambi mag catch
- BCM pistol grip and gunfighter stock
- BCM A5/intermediate receiver extension and A5H2 buffer
- Fortis LE end plate K1 castle nut
- Springco green rifle spring


I like the look of the Fortis after installed, and it was fairly slick and easy to get on. I used my castle nut tool to tighten about 1/4 turn beyond hand tight. Wouldn't say this is necessary versus staking, and adds some cost, so definitely not for everybody. But it seemed like an elegant solution, easy to install, strong and nicely finished, and locks up really tight. I wanted to try one out on one rifle. Will update if I see any issues like working its way loose.

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[Duffy]

Castle nuts should be staked in 2 places. For gaming and recreational ARs, you may have more tolerance for malfunctions from not following established best practices, but don't take your chances on defense and duty ARs.

[maximus83]

Agree that is established best practice, and is what I have on my other rifles. This won't be used for H.D. rifle purposes unless/until I've established that the part works as advertised. I think it's an interesting innovation and don't mind trying on a non-defensive rifle, but have no dog in the hunt and nothing to gain, if it doesn't work, I'll just swap it out for a traditional staked castle nut. If it does work, it would be a handy innovation.

[tehpwnag3]

Your weblink to Fortis is giving my anti-virus fits. The only reason why I clicked on it was to see better detail of the parts.

[tehpwnag3]

From the pictures I'm seeing online, is your castle nut on backwards?

[maximus83]

Yeah I think it is :-)--it's supposed to be a tapered type of castle nut, that's how they get rid of the need for staking/ratcheting. I just put it on their quickly last evening but haven't torqued down super tight yet, as I want to get a dedicated castle nut wrench before I finish it--that's what I get for getting in a hurry. I think that spanner wrench on my AR multi-tool will gouge it badly if I try to really torque it down to its final position.

I had called Fortis this morning to ask about their testing. They said they've had really good luck with it, they've sold over 5,000 of them and not a single report of failure or coming loose once it's torqued in place. Also, you can remove it and reinstall, they've tested that as well as testing the whole solution on a tumbler machine extensively to see if it would come loose. It's kind of an interesting solution, hope it works and stays solid once I torque it down.

[tehpwnag3]

How does it work? Is there a detent mechanism or is it friction fit? Can it be staked if you wanted it to be without chewing it up?

[maximus83]

It's a tapered device that uses what looks to me like a friction fit-only to seal against the end-plate. They also have a "K2" version of this which uses what looks like a c-clip with a detent--but that's not the one I have, so can't tell you what it looks like. Like I said I haven't torqued down to final position, they say only 15 ft./lbs is needed--I'm waiting for my castle nut wrench to get here from Primary Arms so I can torque without chewing up the finish. When I get that and get it seated into final position on there, I'll send an updated close-up pic of what it looks like.

As to staking: good question.

[tehpwnag3]

It looks nice. Hope it holds up for you. May I suggest a drop of Loctite as an extra measure?

[1168]

Interesting idea. While the taper should be able to hold the endplate on without vibrating off, I wonder how it will hold up to rotational forces on the buttstock, since it uses a reduced torque spec. It says it weighs .59oz. Does anybody know what the standard Colt parts weigh? More out of curiosity than the desire to lighten up that part of my rifles.