Glass half full take:

With not too much effort, you can reliably get it to do one thing very well. It does that one thing better than all of the competition. In fact, it does that one thing with the same ROF as the real thing.

Got a 16 inch carbine running with an FRT today using a H3 5.4 oz buffer and a XP recoil spring (red) on brass cased ammo (probably AE 223).

Very finicky with steel case, multiple stuck cases with one requiring a freezer, hammer and cleaning rod.

Ran perfect on the brass cased ammo. Have a 4.6 oz buffer enroute to try the cheaper, underpowered steel case.

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Uh, no.
Opinionated much? Enjoy your binary trigger. Not even in the same class if you're looking for a ROF equal to full auto. I can't tell the difference between mine and my Colt M16A2. Would I like a third position? Sure! But hardly a deal killer. I don't use my AR for precision shooting or hunting.

As far as the buffers...? Unfortunately H3 carbine buffers are hard to find right now. Not sure why ANY buffers would be; it's not like they're that complex to make? If someone has a source for Colt H3s please do pass it along!
I'm slightly curious as I can't find anyone that will at least hazard an educated guess why it will or won't run any better in my gun? H1 runs like a champ. H2 stops after every shot. MY guess is that an even HEAVIER buffer will likely not even fire? LOL
Anyone willing to take a stab?

I'm assuming that the heavier buffers need heavier springs to function right. I haven't tried so I guess that's my shot?  I couldn't really figure out why some of the others buffers I used didn't work like the Cozad 3oz, as it is the same weight as a carbine but the carbine buffer ran flawlessly. However, it does have a piston design with anti bounce weights inside Only thing I can thing of is that with the springs I used, the extra piston design caused the buffer to go back into battery with more force than the buffer weights and spring could allow. Maybe I should attempt a heavier spring. Only problem I can see with that is it can cause short stroking on mid-lengths that are aren't gassed enough.

I'm not complaining that my totally stock out of the box Colt 6920 runs 100% without five minutes of tinkering. I think it's my nature to experiment.
If I understand you correctly, the next heavier buffer will of course run worse? The only other direction to go would be the spring?
If that's the case, I may just leave well enough alone.
I can't find any H3s anyway.

After seeing a video of the "Reset bar" setup it is going to fail. It's just going to, I'm not surprised that they're failing in 100rnds. I'll be surprised if they make it to 200. That spring set up is under thought and poorly designed. It's likely a well made trash product. They need to completely redesign that forced reset mechanism. I work with small springs on a daily basis. Some sort of leaf or torsion spring would be a massive improvement. 0/10 Complete waste of money. Run from this product.

Mine made it to 250 on the first outting, and looks just fine. Color yourself surprised

I just went over 1,500 rounds since installing mine with no issues whatsoever.

I need one!

If it wasn't for the colt requirement on the buffer I would say get a SI optimus buffer so you can configure the weight to need. Just got mine in and will report how it does when my dedicated lower arrives. Plan to try my Tubb spring and Sprinco white and blue springs with it and if all else fails try my A5 buffer tubes since I have all the A5 buffers weights from 0 to 4 and a green Sprinco too if the Vltor springs a no go. My binary triggers (BFS III and 2x ITF) all like the A5 system regardless of buffer weight from 10.5 to 20" uppers so I hope to find a good combo for the FRT. Need to convince my Chief to get me a heat sinked upper......

I'm up to 300 rounds no issues other than some peening. I guess the fix here is a little WECSOG dremel action? I wonder if RBT will offer replacement levers at some point?

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According to them, this is normal. Some people don't see the wear because their carrier m16 cut is further back than forward. I'm assuming most of the people who have the spring issue have a more "forward" m16 carrier cut.

Interesting, I did not know that M16 cuts were slightly different, makes me wonder how the timing tripping the auto sear would be off in a real M16.

It is an easy enough part to copy if they won;t offer support for it.

I mean you're talking millimeters or less, but a sear and sear pin/spring work more efficiently than this setup because it have a torsion spring among other well thought out differences.

Meh, I sold mine sticking to my transferable Mac.

Dias get by with a regular compression spring. I haven't heard of them wearing out regularly.

IMO, they should have designed it so it can't pivot far enough forward to pinch the spring.

The PSA carrier in the shop gun we were dicking around with didn't cause any marks on the safety latch so far. I'll measure the carrier at some point.

H2 works well, H1 goes brrrt even better. Didn't try an H3 yet.

Rare Breed FRT15 trigger back in stock at the time of this post!

https://www.rarebreedtriggers.com/product/frt-15/

AND GONE

In stock At BDU again.

Thanks for the heads up. Finally got in on a batch.

Mulling over buying a second though I don't really want too. Just so I can have a spare part one. Really wish someone with the skill would make some spare bars for it or rare breed do it themselves.

Why?

In case those of us modding them for reliability screw up the dremel cut on the bar or if they receive too much wear from slightly longer cut M16 profile BCGs which are cutting into the top of the bar. Would rather have a spare than modify a bolt if needed after the reliability mod depending on which of my 20 uppers I use this gives me some leeway in case. Got two of everything I need to do ahrion's mod but I would like to try one like yours if possible that keeps the spring stock, just gotta find the right screw as I dont wanna buy a pack of 100 and I have no home depot around and maybe add an o-ring as backup if I can figure out the size for the stock spring.

Edit ain't gonna lie I am nervous of screwing up the cut and turning it into a $400 brick and dont wanna buy another cause that money just went to a Chiappa Rhino revolver and a PTR-9CT, gotta get it while price was still normal with how Biden ran his mouth on gun control thanks to the Colorado shooting.

I don't see a reason to cut the bar to accommodate differences in m16 carriers. There is already a lot of leeway when the locking bar fully compresses the spring.

If you have a vise, put the locking bar in the vice for the bevel mod. Only way you can mess up is if you're sloppy, fast, and have cerebral palsy.

Ah. I think I was misunderstood. The mod isn't to the locking bar for the carriers, the mod is to radius the leading edges of the carriers https://www.youtube.com/watch?v=Hr_MUkUp_r8&t=311s

Yeah I still figure to do the mod but have seen two different versions of the cut. Some say bevel it at an angle towards the hole and some just do a crescent cut with no bevel. I assume the bevel with crescent is correct and wish the youtube videos could focus the camera enough to show a better look at the angle, after all even going slow so as not to mess up I could go to steep or too shallow on the angle. A drawing attached in the video would have been a good idea as the glare on the part makes it hard to see too even in photos. I have no problems cutting and working on ARs but this trigger thing is getting me nervous for some reason. Even the ITF binary trigger didn't bother me working on it but its parts are easy to obtain if messed up.

I can see the cuts you made in your mod pretty good but wasn't yours specifically cut for your spring change? I wanna try the regular cut and spring first and add a guide rod and oring if I can find one then if that still has issues do your mod with the bolt catch spring and parts. Wanna work my way through it and try to stay stock as possible in case further development or official updated parts ever get released.

I wanted to update everyone on the trigger spring replacements from McMaster. I have listed them below from highest spring tension to least. We already know the current trigger spring yields about 2 lbs - 2.5ish lbs pull weight and is NOT ground on each end of the trigger spring.  (1) yields about 3 lbs 12 oz - 3 lbs 14 oz pull weight and is the smaller OD/ID of all the springs I tested. (2) is about 2 lbs 10 oz average, which is only slightly more than the stock spring. (3) I didn't even test because it was less tension as is than the stock spring. It's important to note that each of these spring are slightly longer than the stock spring and all of these springs are ground on the ends. It's also important to note that the infamous "click" when the trigger resets is MUCH more noticeable with (1) & (2) because of the "hair" longer spring and the increase in trigger spring tension. I am confident (1) will serve me much better and will work much better than the stock configuration, as right around 3.65 lbs - 3.85 lbs is over a pound of pull weight than the stock trigger AND the spring is slightly longer to help that reset. I will likely run this setup moving forward.

1.  2022N117 - Mil. Spec. Compression Springs, 0.25" Long, 0.18" OD, 0.128" ID, 57.8 Ibs/inch Spring Rate

2.  9657K608 - Compression Spring, 0.25" Long, 0.210" OD, 0.158" ID, 41 lbs/inch Spring Rate

3.  9657K607 - Compression Spring, 0.25" Long, 0.210" OD, 0.166" ID, 21.5 lbs/inch Spring Rate

You're probably wondering why someone would change that tiny trigger spring. There are a few reasons I can think of. First being the trigger pull weight is anywhere between 2 - 2.5 lbs pull AND some of our triggers aren't resetting OR it's hard to do an intentional single shot. Why would we want to change the spring? Well if we change the spring to have more tension on the trigger, there's more chance it will reset with less effort from the hammer because sometimes it doesn't reset because we're holding it too tight or the carrier doesn't have enough force to reset the trigger, resulting in an unintentional "single shot" that requires a charging handle rack to re-cock the hammer. Also, if the trigger spring has more tension, it will push our finger forward with less issues when resetting. Lastly, we will have more control of when or if we want to intentionally do a single shot. Right now it takes a skilled finger to do that.

All in all, I would say this is another successful mod. I won't really know until I got the range, but I couldn't see any downsides to this.

You can't source it elsewhere? You must live in the boonies?
I suggested HD but there must be online sources? I didn't price them but I'd buy a 100 screws just to guarantee a permanent fix.

I think you can do the dremel mod. I have faith in ya' man!

My cut was.specifically to keep the locking bar from ruining the spring. There are zero downsides to doing the locking bar bevel.

Not sure if this was said yet, but anyone in desperate need of an h3 buffer can assemble one fairly quick with few extra carbine buffers, a punch and a hammer.

So I assume your cut wasn't specific to your spring setup and was the regular crescent cut to prevent kinking? When you made the crescent cut did you do you at an inward angle to the hole the spring rest in of just a straight cut in a crescent shape?
EDIT: i'll try to do a crap drawing to explain what I'm asking, I don't think I am clear enough.

Basically are you dremeling a bevel at an angle towards the hole the spring rest in with the dremel bit or will just head on parallel to the locking bar be ok as long as both make a crescent shape when viewed from the bottom of the locking bar? Drawing could be clearer but I suck, looks better on real paper than photo shows. i have seen it both in videos and all resulted in a crescent shape just need to know if its better to bevel it at inward angle to add a slope.

Thanks for the info been waiting to see how everyone's test went for the trigger springs.

I really think your overthinking it. Simply just dremeled it like my pics. Would I say they are required for my mod? Yes. Do they help prevent kinking for the stock spring? Yes.

Personally I ground it at a slight angle. I posted links in one of my YT vids.
Maybe this will help?

https://imgur.com/IRRqfz6

Yep thats exactly what I needed to know. Thanks.

@haveTwo - you may be interested in this thread.

Anyone have experience with this ADM Buffer, or Surefire's OBC556?

Both seem to address bolt bounce, and I'm wondering how useful either may be.

Get me measurements and I'll see. Obviously it has to be softer than the carrier but perhaps there's a better material to choose.

anyone run this trigger with this bcg with no issues?


Spikes Tactical BCG

I have a few thousand rounds through a 10.5” pistol build I put together with the FRT and a recoil spring/buffer assembly I built myself which is approximately equivalent to an H3.  Great ROF and reliability. I’m using a Faxon BCG and have only very light peening that has not progressed at all since initial break-in.

You have a picture of the bottom? That’s what matters.

ETA: it says full auto spec so it should be gtg.

I would be extremely surprised if a Spikes Tactical BCG didn't work with a RB FRT (If you know what I mean).

Sear fix

Big Daddy Unlimited has 9 of these in stock as of today. They had 51 earlier in the week. Apparently people took notice, ha.

They should just sell a mod kit.

Kind of surprised this is a paid fix. If they know there is an issue, why not just take care of it? smh

Different company from Rare Breed. This is an aftermarket modification.

They are also providing ATF with material....



Do they really need that to market the job? And all their pictures call it a "sear".

Anyone else have the anti walk pins provided have too much side to side play on the lower, bout a mm to long? Don't think it would do anything bad but its annoying me and I think I'll have to get a KNS set.

EDIT: now noticed Rare Breed sells just the FRT spring https://www.rarebreedfirearms.com/locking-bar-spring/ and antiwalk pin and antiwalk pin screws as seperate parts. Maybe they will the locking bar too.