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Thread: Long stroke SureFire Carrier

  1. #11
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    Interesting.
    The way I see it, as the BCG in an AR moves rearward, there are 4 significant milestones. #1 the point where ejection occurs, #2 the point where failure to feed would happen if rearward movement stopped, #3 the point where failure to lock back would happen, and #4 the point where the reciprocating mass (BCG and buffer) hit the RE and stop, contributing to recoil.
    This system gives more distance between #3 and #4, ensuring reliability while giving more time for the spring to slow down the reciprocating mass prior to #4. This should mean less recoil, I would guess. It probably shoots like a gun with the adjustable gas block turned down to the ragged edge while still being reliable.
    I'm sure there is more to it but that seems pretty cool. It kind of reminds me of the ultimax 100 LMG, which is designed with a "constant recoil" where the reciprocating mass never hits the rear, it is always under spring power.
    Last edited by P2000; 06-04-16 at 00:08. Reason: duplicate sentencs

  2. #12
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    Quote Originally Posted by P2000 View Post
    It kind of reminds me of the Ultimax 100 LMG, which is designed with a "constant recoil" where the reciprocating mass never hits the rear, it is always under spring power.
    Makes sense since Sullivan led the engineering team that developed the Ultimax.
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  3. #13
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    Quote Originally Posted by Dionysusigma View Post
    Interesting. I learned about the Ultimax 100 from this "Carnik Con" youtube video: https://www.youtube.com/watch?v=bTwkM7gpx5E

    If you guys haven't watched Carnik Con on youtube, he is hillarious. Amazing guns, hillarious comedy, and good facts too. Trey Knight even makes a cameo, which I guess is where the weaponry comes from.

    In this video, you can clearly see the Ultimax 100 have a lower cyclic rate and much, much less recoil than all of the other LMG's. It really is neat, the reciprocating mass is always under spring power during it's travel (never hits the rear), and the instant the reciprocating mass hits the front the next round is fired. So the rearward force of the round being fired is equal to the forward force of the reciprocating mass stopping at the front. Watch the vid, his t-shirt doesn't even jiggle. That LMG is awesome.
    Last edited by P2000; 06-05-16 at 21:42.

  4. #14
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    Quote Originally Posted by tom12.7 View Post
    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.
    So is the cam pin path extended or different than a regular BCG? From reading the vague descriptions floating around the web I didn't see that.

  5. #15
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    Sullivan's improved carrier included altered timing. Not sure if SF decided to include that. I've been interested to see how Sullivan decided to keep the carrier speed in check with the altered timing.

  6. #16
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    Quote Originally Posted by P2000 View Post
    Interesting.
    The way I see it, as the BCG in an AR moves rearward, there are 4 significant milestones. #1 the point where ejection occurs, #2 the point where failure to feed would happen if rearward movement stopped, #3 the point where failure to lock back would happen, and #4 the point where the reciprocating mass (BCG and buffer) hit the RE and stop, contributing to recoil.
    This system gives more distance between #3 and #4, ensuring reliability while giving more time for the spring to slow down the reciprocating mass prior to #4. This should mean less recoil, I would guess. It probably shoots like a gun with the adjustable gas block turned down to the ragged edge while still being reliable.
    I'm sure there is more to it but that seems pretty cool. It kind of reminds me of the ultimax 100 LMG, which is designed with a "constant recoil" where the reciprocating mass never hits the rear, it is always under spring power.
    I've always felt that AK reliability was partly due to the increased gap between #2 and #4.

    If the bolt carrier normally cycles back fully to #4, friction due to foreign debris might cause a cycle where the carrier did not retract all the way. The increased gap in an AK will allow the bolt to still pick up the next cartridge.

    The #2-#4 gap in AR systems is about 1/2" , depending on the magazine timing. I've never measured it on an AK, but it seems longer there.

    This is a very interesting development.
    Last edited by StainlessSlide; 06-08-16 at 04:10.

  7. #17
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    Quote Originally Posted by tom12.7 View Post
    Sullivan's improved carrier included altered timing. Not sure if SF decided to include that. I've been interested to see how Sullivan decided to keep the carrier speed in check with the altered timing.
    IIRC he used increased carrier mass.
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  8. #18
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    Quote Originally Posted by BufordTJustice View Post
    IIRC he used increased carrier mass.
    That was also part of it. Not sure if that was all of it or not.

  9. #19
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    interesting design, now how dose this compare to say gemtechs adjustable bolt carrier? wondering what would be theoretically, a better way to address suppressed reliability,

    currently running a 10.5 MRP, with JP silent capture spring and have no issues, good ejection patterns, reliability with LMT EBCG

    now the MWS with 16 inch CL, runs hot and hard, but dead reliable, even with a can, with 18inch SS, runs little smoother, ejection goes from 1 o'clock to 3 o'clock. would love to get a little smoother with the 16 inch barrel

    thinking I may want to give the gemtech SBC a try for the 16 inch barrel, (love velocity), or maybe just say **** it and cut the 16 back to 13.5 and reprofile. should address some of the overgassing issue

  10. #20
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    Quote Originally Posted by tom12.7 View Post
    That was also part of it. Not sure if that was all of it or not.
    Agreed. I seem to recall some type of sprung mass as well. Not sure if it was contained in the carrier like SF or in the buffer assembly.
    "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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