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Hi there,

I have searched on several forums and am hoping to find the answer to this question here. I am interested in putting a Rare Breed force reset trigger into an HK MR556A1. This is my first HK; I have several Daniels, Springfields, etc however am noticing the following:

  • When putting in the FRT-15 trigger pack, one of the openings on the lower for the anti walk pins that it comes with doesn't align and as such it is VERY difficult to get the anti-walk pin in there.
  • After I re-connect the upper and lower, and test fire, the hammer will not release when pulling the trigger. The latch on the top of the package needs to be pushed forward slightly by the BCG however it isn't doing that.
Honestly I am wondering if the FRT just isn't compatible with the HK and I should just put it in one of my other rifles. Does anyone have any thoughts experience with the FRT-15 or binary triggers in general on the MR556A1?

Thank you
 

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I would not run it in an MR556. First, the bolt carrier is not mil spec so it won't even make contact with the trigger release bar unless you replaced the bolt carrier. Second, you are going to run into buffer weight issues right out of the gate on the gun. Third, you're turning a perfectly good HK into a one trick pony, that is pretty much useless beyond pretend FA / burst fire runs at the range. Throw all accuracy out the window and take any optic you take seriously off the gun because it will largely be totally useless.

With that said, my recommendation is either build or use another more disposable AR that you don't run often that can be adjusted and kitted out for thrills. If you want to run a piston gun, it does work in the Sig 516 with some tweaks which I can review with you in a PM. It will also run in an AR9 with modifications. But honestly 9 out of 10 times, there is just no easy solution to running the RB out of the box unless you very specifically have an old mil spec colt gun or you get super lucky and all your stuff just happens to be in the perfect spec. Because if the timing is off and the hammer goes a hair too soon on pull, you'll get light primer strikes or dead trigger. There's just like numerous parts to tune on the thing. I personally have been trying to run it in an AR9 that takes MP5 mags and it's been a total chore. Still not running correctly.
 

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I would not run it in an MR556. First, the bolt carrier is not mil spec so it won't even make contact with the trigger release bar unless you replaced the bolt carrier. Second, you are going to run into buffer weight issues right out of the gate on the gun. Third, you're turning a perfectly good HK into a one trick pony, that is pretty much useless beyond pretend FA / burst fire runs at the range. Throw all accuracy out the window and take any optic you take seriously off the gun because it will largely be totally useless.

With that said, my recommendation is either build or use another more disposable AR that you don't run often that can be adjusted and kitted out for thrills. If you want to run a piston gun, it does work in the Sig 516 with some tweaks which I can review with you in a PM. It will also run in an AR9 with modifications. But honestly 9 out of 10 times, there is just no easy solution to running the RB out of the box unless you very specifically have an old mil spec colt gun or you get super lucky and all your stuff just happens to be in the perfect spec. Because if the timing is off and the hammer goes a hair too soon on pull, you'll get light primer strikes or dead trigger. There's just like numerous parts to tune on the thing. I personally have been trying to run it in an AR9 that takes MP5 mags and it's been a total chore. Still not running correctly.
Hi Sirris, I just got an Rare Breed installed and bought an Adams Arms adj block piston upper for it- I can run about a half mag before it turns into a single shot w light primer strikes on the non-fired rounds. I do have an upper it works on, but it's a direct impingement .223 Wylde, w a thermal scope. That's not what I want to play on. Also have a stock S&W M&P15 upper that gives the same light strike misfire. I'd like to get that Adams Arms up and running. I haven't heard back from Rare Breed yet on this- is there anything you'd suggest? Thanks, Geoff
 

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Hi Sirris, I just got an Rare Breed installed and bought an Adams Arms adj block piston upper for it- I can run about a half mag before it turns into a single shot w light primer strikes on the non-fired rounds. I do have an upper it works on, but it's a direct impingement .223 Wylde, w a thermal scope. That's not what I want to play on. Also have a stock S&W M&P15 upper that gives the same light strike misfire. I'd like to get that Adams Arms up and running. I haven't heard back from Rare Breed yet on this- is there anything you'd suggest? Thanks, Geoff
Honestly there are major timing issues that start coming up as you get farther into the mag dump. Everything must be exactly in spec & weighted properly & lubed correctly. Truth be told, I gave up on AR variants & migrated the kit to an MPX Copperhead w/ trip kit. Runs flawlessly. Getting away from buffer systems & just letting the timing of the carrier & bolt lock do the work solved all the issues with the system.
 

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Anyone else’s checking this post to see what exactly a FaRT-15 was?
 

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Damn, I have seen plenty of legal letters in my career, and that is one very well written response letter!

I'm glad RBT has hired competent legal counsel.
 

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MP5 Sear, MP5 RR, MP5F, MP5N, Mk23, P30, P30L, 4 USPC's, MR556, MR762, HK45 Tac, P2000SK, VP9
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I bet it's failing the cork test. They'll shove in a tapered cork into trigger guard, and if it shoots twice it's a machine gun. The cork compresses under a forced reset, and rebound pressure can be enough to fire again. I designed a similar system over 15 yrs ago, and this is what got me. I tried to get around it but moved on to more interesting things. Once the American invents act got passed I was screwed. First to invent became first to file. I wish them the best!
 

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ATF just raided them. Look forward to those becoming classified as machine guns soon. Should this go up in NFA talk?
Good info...

Mods, if this is a bad place, let me know.
 
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So I google John Crump FRT15, find this that says its 4 hours old:
Purple Rectangle Violet Font Magenta

Click on it and find this:
Font Screenshot Parallel Number Rectangle

Possibly a result of RBT calling the info out?? I hope so!! I hope Rare Breed takes all nay sayers to the mat!!
 

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Well then. I stand corrected. That's misinformation in real time.

Jared usually has solid info and is ahead of the curve. Guess he checked his sources and made a correction as well.

I won't pass on OSint again unless it's verified.
 
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