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Thread: Best Suppressed SBR Ever????

  1. #1
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    Best Suppressed SBR Ever????

    The First Problem: Suppressed AR’s have a lot of felt recoil, increased amounts of carbon build up at faster rate, slower on target for follow up shots and burn lubrication off faster.

    The First Solution: Build an AR with a much smaller gas port size so that it can utilize the back pressure generated by the suppressor to cycle the weapon.

    The Second Problem: Dedicated suppressed AR’s will not cycle enough to pick up a second round, making the weapon useless if the suppressor becomes damaged or removed.

    The Second Solution: Find a gas port size that is just big enough to cycle the weapon without the suppressor, but small enough to not exhibit the issues listed in problem one. Then find a way to slow dwell time down in order for the extractor to remain on the casing as long as possible so that the ejector can remove the spent casing and pick up a new round.



    Exhibit A: 10.5” upper that is setup specifically for suppressed use.

    When I built the 10.5 upper some twelve months ago, I did not realize that I got it just right from the beginning (will explain what I mean later). Below are the specs on the 10.5 upper:

    1. Noveske 10.5 N4 Light (with small gas port)
    2. LMT Enhanced Bolt Carrier.
    3. LMT Standard Bolt
    4. M4 Upper Receiver
    5. VLTOR CASV (Mid)
    6. H2 Buffer
    7. Tactical Spring Co CS Buffer Spring
    8. SureFire MB556
    9. SureFire K Can
    10. PRI Gas Buster Charging Handle






    Above upper has been through two carbine schools with about six thousand rounds through it. No issues shooting suppressed or none suppressed.

    With the success of the above 10.5, I wanted to try and create a better mouse trap by using the new KAC URX II, Fail Zero M4 Upper Receiver, Fail Zero BCG and a Noveske 11.5” N4 Light barrel with a small gas port.

    We ordered the custom 11.5 N4 Light from the good folks at Noveske and acquired the URX II and Fail Zero items. After machining down the Noveske GB to fit inside of the URX II, we assembled the upper. The lower used was the same one that I used on the 10.5 upper mentioned above. It had an H2 buffer and Tactical Spring CS buffer spring in stalled in it.

    For testing purposes, I loaded up a PMAG with one round and installed the SF K Suppressor on the barrel. Fired one round. BCG locked back. SUCCESS! Wanting to see what I could get away with, I installed an H3 buffer. Loaded one round and got the bolt to lock back again! Cool I thought. Now let’s test this upper WITHOUT the suppressor on it (as I need the weapon to still cycle without the can on, but does not need to lock back). There is a VERY fine line here between the weapon extracting the round, picking up a new round, but not locking back.

    With the suppressor off, I loaded one round into the mag and fired the weapon. No brass came out. Hmmm. I pulled back the CH and ejected the spent casing. I removed H3 buffer and installed an H2 and tried it again. No joy. Removed the H2 and went to an H buffer. Still no luck. Removed the H and installed a Car Buffer. Again, no luck. Now I am really wondering what is going on. The spring that is installed in the lower is a CS spring so I thought that was what was doing me in. I grabbed a standard SS carbine buffer spring and stayed with the Car buffer. Same result. The casing had to be manually removed. Grrrrrrr!!!

    At the end of my rope with this configuration, I told Adam (board member that works in my shop part time) what was happening and he suggested that we install the LMT Enhanced Carrier that we used in my 10.5 upper. I said; “that won’t make any difference as it is actually going to remove more pressure and make it worse.” Boy was I wrong! This is where the story gets interesting and is the lesson on extractor dwell time.

    I removed the Fail Zero BCG and installed the LMT Enhanced Carrier and Standard Bolt. I kept the SS buffer spring and Car Buffer. The suppressor is still off the weapon. I loaded one round and fired the weapon! VICTORY! The casing ejected from the weapon! With this success, I loaded up two rounds in the mag to see if the BCG would come back far enough to pick up and load the second round. Success again! Now I wanted to see how heavy a buffer I could get away with. I tried H, H2 and H3. All worked with the H3 pushing the envelope and only getting an ejection distance about two feet.

    So how can this be? How can the LMT Enhanced Carrier make this big of a difference??? Remember that the gun would NOT EJECT the casing at ALL with the standard BCG, but with the Enhanced Carrier I could run all the way up to an H3 buffer and it would eject and pick up the next round. What is happening with the Enhanced Carrier has slightly angled cam area which helps with bleeding off excess gas (slowing everything down). This allows for more positive extraction which in turn allows the ejector to push out the spent casing from the weapon. Simply fascinating stuff and if you would have told me this, I would said BS!

    Commonly, we have view the LMT Enhanced Carrier as a useful tool for helping bleed off excess gas on a suppressed weapon. I also now view it as a good idea for guns that are short stroking as well.

    The last little piece of info I have gotten from this build is that a suppressor generates at least DOUBLE the pressure created by the cartridge. So if you have an AR with an above average gas port (BM, Oly, DPMS, all piston operated AR’s), you are going to get at least double the felt recoil (if not more)!


    Exhibit B:

    1. Noveske 11.5 N4 Light (with small gas port).
    2. KAC UXR II
    3. LMT Enhanced Bolt Carrier
    4. Fail Zero Bolt
    5. Fail Zero M4 Upper Receiver
    6. SureFire MB556
    7. SureFire K Can
    8. PRI GB CH
    9. SS Car Buffer Spring
    10. H3 Buffer









    C4
    Last edited by C4IGrant; 07-05-09 at 08:36.

  2. #2
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    Excellent!! Can't wait to give you $$$$.

    Thanks for sharing your smarts... Gonna be nice to have a 1st class SBR & doing it right the first time. Couple of questions.

    Is there any real pro / con (or personal preference) for 10.5 vs. 11.5 set up?? The low recoil & using it 100% suppressed is my main goal for an sbr & oal is not really a factor for my application.

    How much does the quality of the can come into play with reliability?? My initial thought was one of your uppers and an m4-1000 can (only due to the fact of my class III contact) I'm just guessing different cans could cause different pressures for the gas system??

    Thanks C4
    "You cannot invade the mainland United States. There would be a rifle behind each blade of grass."
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    Thats cool stuff Grant. I guess you will be building the upper for the lower your sending me One question though, is there a difference between 10.5 and a 11.5" barrel? And if so what are the pro's and con's of them? Thanks

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    So, if I am tracking right the lighter the buffer the less felt recoil. With the Enhanced carrier you get reliable opeation thru H3, could you reduce the size of the gas port further and get down to a H or standard buffer with reduced recoil and even less gas back in the upper?
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    Looks like its time for me to start saving my allowance. How much would a complete set-up like that cost?
    I know of no safe depository of the ultimate powers of the society but the people themselves; and if we think them not enlightened enough to exercise their control with a wholesome discretion, the remedy is not to take it from them but to inform their discretion.

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    Wow, good info Grant.

    So now the magic question... Can we order this barrel with the small gas port from Noveske also or are you going to be the only source?

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    Hi Grant,
    Excellent writeup, and as usual, a question or two,

    1. When an AR doesn't lock back on the last round, does this usually mean that the carrier is traveling so fast, that the follower in the mag doesn't have time to "catch up", thus preventing the bolt locking back?
    OR, does is sometimes mean the carrier simply isn't traveling REARWARD enough, in order to lock back?


    If the carrier is just "outrunning" the mag spring/follower, I'm wondering if Wolf extra power (10%+?) mag springs wouldn't be a solution here?

    SO,

    2. Have you tried the Wolff extra power/+P mag springs, in an attempt to get the bolt to lock back 100% of the time, even when unsuppressed???

    It would be simply amazing if this setup worked 100% reliably EVEN WHEN UNSUPPRESSED. ????
    "ROLL RIGHT SNIPER!"

  8. #8
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    It's the altered cam angle on the enhanced carier. It allows the residual chamber pressure to drop for a few more milliseconds.

    It allows for a much more relaxed piece of brass at the start of extraction and makes for a much easier job for the bolt.

    It is a shame someone won't make an otherwise conventional carrier with the altered cam angle.

    Perhaps if someone with connections suggested it to LMT *cough*Grant*cough*, they would consider doing so.


    I am not sure if the cam angle itself is covered by a patent. I think it is the same as the Stoner 63.


    How about say a G&R Tactical enhanced carier???


    Hmmm???????
    Last edited by Heavy Metal; 07-04-09 at 21:02.
    My brother saw Deliverance and bought a Bow. I saw Deliverance and bought an AR-15.

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    Quote Originally Posted by Josh-L View Post
    Wow, good info Grant.

    So now the magic question... Can we order this barrel with the small gas port from Noveske also or are you going to be the only source?
    I'd like to know this as well :-)

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    My LMT with the enhanced BCG will cycle PMC Bronze running an H-buffer.
    With 5.56 pressure ammo I am almost positive it would cycle an H-3.
    I have and others have commented that my ejected brass doesn't get beat up as much compared to other M-4 clones that I have seen.

    Grant have you thought about having the LMT enhanced carrier coated with NP3 or some other kind of coating so that you can gain back some of the benefits you were trying to archive with the Fail Zero carrier[running less lube].
    Last edited by Thomas M-4; 07-05-09 at 00:47.

  11. #11
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    Nice upper.

    What I have found for canned use is:
    Noveske Switchblock
    Noveske N4 10.5
    Lt stealth upper
    DB youngs bcg
    Pri gasbuster
    Hk 416 buffer and spring.
    Been shooting this my last couple of outings suppressed only, because that is the point of this upper. Fully cycles and locks back even with green/white box remington ammo. Althought I have not tried the upper on the unsupressed settings with the can removed I dont even want to. I think for unsupressed use I would go with another setup just becuse of poi changes with removeing the can which is the old M4 2000 18 tooth setup.

    But I am realing liking this setup for canned use as it is as smooth as a slicked up 10/22 recoil wise.

  12. #12
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    Quote Originally Posted by sapper36 View Post
    Thats cool stuff Grant. I guess you will be building the upper for the lower your sending me One question though, is there a difference between 10.5 and a 11.5" barrel? And if so what are the pro's and con's of them? Thanks


    The 11.5 gives you a much longer frag range than the 10.5. It also allows you to run a longer rail.



    C4

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    Quote Originally Posted by Artos View Post
    Excellent!! Can't wait to give you $$$$.

    Thanks for sharing your smarts... Gonna be nice to have a 1st class SBR & doing it right the first time. Couple of questions.

    Is there any real pro / con (or personal preference) for 10.5 vs. 11.5 set up?? The low recoil & using it 100% suppressed is my main goal for an sbr & oal is not really a factor for my application.

    How much does the quality of the can come into play with reliability?? My initial thought was one of your uppers and an m4-1000 can (only due to the fact of my class III contact) I'm just guessing different cans could cause different pressures for the gas system??

    Thanks C4
    A can is a can when it comes to back pressure. Where the difference in cans shows itself is in POI shifts.



    C4

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    Quote Originally Posted by FromMyColdDeadHand View Post
    So, if I am tracking right the lighter the buffer the less felt recoil. With the Enhanced carrier you get reliable opeation thru H3, could you reduce the size of the gas port further and get down to a H or standard buffer with reduced recoil and even less gas back in the upper?
    You could reduce the gas port some and get it to work only with say a car or H buffer. This is a VERY fine line though and the gas ports on either weapon are VERY tiny already.

    If I wanted to run just an H buffer, I would install the CS buffer spring. What we noticed though is that the SS buffer spring and the H3 buffer, it has a more "on target" recoil pattern.



    C4

  15. #15
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    Quote Originally Posted by HwyKnight View Post
    Looks like its time for me to start saving my allowance. How much would a complete set-up like that cost?
    Don't really know. I would say that it would be similar to the URX II/BCM build we have going.


    C4

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    Quote Originally Posted by Josh-L View Post
    Wow, good info Grant.

    So now the magic question... Can we order this barrel with the small gas port from Noveske also or are you going to be the only source?
    Noveske does not sell N4 Light barrels stripped so you would have to get them from us and then we would build the upper.


    C4

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    Quote Originally Posted by Paul Cataldo View Post
    Hi Grant,
    Excellent writeup, and as usual, a question or two,

    1. When an AR doesn't lock back on the last round, does this usually mean that the carrier is traveling so fast, that the follower in the mag doesn't have time to "catch up", thus preventing the bolt locking back?
    OR, does is sometimes mean the carrier simply isn't traveling REARWARD enough, in order to lock back?

    If the carrier is just "outrunning" the mag spring/follower, I'm wondering if Wolf extra power (10%+?) mag springs wouldn't be a solution here?
    This can be a reason, but 90% of the time it is because the weapon is short stroking.



    2. Have you tried the Wolff extra power/+P mag springs, in an attempt to get the bolt to lock back 100% of the time, even when unsuppressed???

    It would be simply amazing if this setup worked 100% reliably EVEN WHEN UNSUPPRESSED. ????
    I have mags with high end CS springs. It does not make a difference.

    The 10.5 has ALWAYS run 100% without the can on and so far the 11.5 does as well.


    C4

  18. #18
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    Quote Originally Posted by Heavy Metal View Post
    It's the altered cam angle on the enhanced carier. It allows the residual chamber pressure to drop for a few more milliseconds.

    It allows for a much more relaxed piece of brass at the start of extraction and makes for a much easier job for the bolt.

    It is a shame someone won't make an otherwise conventional carrier with the altered cam angle.

    Perhaps if someone with connections suggested it to LMT *cough*Grant*cough*, they would consider doing so.


    I am not sure if the cam angle itself is covered by a patent. I think it is the same as the Stoner 63.


    How about say a G&R Tactical enhanced carier???


    Hmmm???????

    Right you are. The angled cam area (which ever so slightly angled) does delay the bolt coming un-locked.

    I wish we had as much pull as you think we do.



    C4

  19. #19
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    Quote Originally Posted by Thomas M-4 View Post
    My LMT with the enhanced BCG will cycle PMC Bronze running an H-buffer.
    With 5.56 pressure ammo I am almost positive it would cycle an H-3.
    I have and others have commented that my ejected brass doesn't get beat up as much compared to other M-4 clones that I have seen.

    Grant have you thought about having the LMT enhanced carrier coated with NP3 or some other kind of coating so that you can gain back some of the benefits you were trying to archive with the Fail Zero carrier[running less lube].
    The NP3 finish, like a lot of the other ones wears off over time. The fail zero finish is actually into the metal as they buy the BCG's in the white.

    The sole purpose for me using the fail zero stuff was to try and run a lube less, suppressed weapon (something the world has never really seen before).

    What I am thinking about now is buying LMT Enhanced carriers (in the white) and sending them to fail zero to have coated.


    C4

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    Quote Originally Posted by C4IGrant View Post
    The last little piece of info I have gotten from this build is that a suppressor generates at least DOUBLE the pressure created by the cartridge. So if you have an AR with an above average gas port (BM, Oly, DPMS, all piston operated ARís), you are going to get at least double the felt recoil (if not more)!
    The physics of recoil don't work that way.....just sayin'.
    FFL/SOT armorer

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