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Thread: Long stroke SureFire Carrier

  1. #1
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    Long stroke SureFire Carrier

    I have publicly commented that this type of design mod would be beneficial....and here it is:


    http://soldiersystems.net/2016/05/25/sofic-suppressed-optimized-bolt-carrier-group-long-stroke-from-surefire/


    Longer stroke via shaving the rear gas key screw and a shortened buffer. THIS is an improvement. I'm excited to see what research SF reveals about their product development.
    "That thing looks about as enjoyable as a bowl of exploding dicks." - Magic_Salad0892

    "The body cannot go where the mind has not already been."

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    I like the idea but, the first thing that jumped out at me is the one gas key screw.

    I'm sure one screw that is of proper material and is installed correctly will be more than enough to secure the key. I also understand that the key will need shortened to gain the desired longer stroke.

    All that but I'm still like "One screw key?!"

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    I'm not sure it's a single screw. From the pics it looks like the rear of the key (and the screw) is recessed into the carrier, not cut off completely.

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    Quote Originally Posted by cynical View Post
    I'm not sure it's a single screw. From the pics it looks like the rear of the key (and the screw) is recessed into the carrier, not cut off completely.
    That's what I'm seeing. Either that or it's in a keyed-slot and installed from the rear (much like a front-to-rear sight dovetail).
    "That thing looks about as enjoyable as a bowl of exploding dicks." - Magic_Salad0892

    "The body cannot go where the mind has not already been."

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    Quote Originally Posted by cynical View Post
    I'm not sure it's a single screw. From the pics it looks like the rear of the key (and the screw) is recessed into the carrier, not cut off completely.
    Quote Originally Posted by BufordTJustice View Post
    That's what I'm seeing. Either that or it's in a keyed-slot and installed from the rear (much like a front-to-rear sight dovetail).
    This sounds more right than what I thought I was looking at.

  6. #6
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    spring loaded counterweight in the end of the carrier , interesting.

    i wonder what they've done with the porting in the carrier

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    This is Sullivan's work. It is interesting to see how the commercial product turns out. None of this is new really at all in concept, I would've hoped that more of this could have been marketed 20 years ago.
    It would be interesting to see how this commercial version compares when looking deeper into things. Extractor pin retention can vary, depending on the extended length of the double cut cam compensation. Extending a portion of the bore for retention can help a lot, but that extended portion must be compatible with the BE, others that do it are not always so. Another interesting thing to see would be the free space in the action buffer, there's possibilities here. The reduced wire gauge spring with more active coils can be a big help here for the action spring, but would really need a production part to test it. With modern machining there are other gas key options that may be better or worse, a partial integral key "may" end up a better solution, depends on the execution of it. Spring loaded weights in the carrier showed up in 5.56 ARs not long after the 9mm AR came about, with different successes, this looks pretty good though.
    This offering may be great, just depends on how they offer it. I would still prefer to back spot face the gas tube hole in the upper for key clearance for added length and use a custom or dedicated charging handle when using the standard M16 FOW upper to extend the cam path and extended bore for retained extractor pin applications.
    Last edited by tom12.7; 06-02-16 at 18:14. Reason: Sorry, accidentally deleted a portion that I added back in.

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    Functionally, what's the difference between a weighted carrier vs. a heavier buffer? Also, what is the purpose of the springs in the carrier? I'm definitely interested in this if Sullivan is behind it.

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    In terms of bounce, there is a big difference between a solid weight or mass than one that impacts at different times. A solid mass carrier with the total mass rebounding off the BE at one time is much different than a spaced in time mass impulse off the BE.
    If we are restrained by a certain total mass, we can look at 3 easy scenarios. We could look at the total mass in a solid carrier. We could look into some of that mass placed into a delay via the action buffer. That buffer mass can be satisfactory, but sometimes it is not. A portion of that total mass may be placed inside the carrier with an offset in timing to reduce bounce further.
    When the carrier hits home, a solid system tends to bounce. Using a portion of that mass in a buffer that is spaced to add a time delay can reduce that, but that impacts in its own time. An offset impact in time addition to the buffer that further disrupts the original bounce harmonic can dampen down those effects further.
    The choices in possible masses are not random, neither is the timing of those.

  10. #10
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    Thanks for your reply; I'm still trying to wrap my head around it. Dealing with bolt bounce, different ways to skin a cat I guess. I seem to recall Sullivan not being satisfied with the carbine buffer construction to address the issue. Since suppressors increase the cyclic rate, bolt bounce would be more of an issue in full auto. Curious what's inside that shorter buffer and the total mass of the reciprocating elements.

    Sent from my SM-T810 using Tapatalk

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