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  1. #21
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    Default Re: What is the shortest 5.56/223 AR15 that will make factor for SAPSA?

    Talking about barrel length, hypothetically, what would happen if you shortened the barrel length from 16" to say 12"??
    Is it even possible?
    Functionality wise I mean?

  2. #22
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    Default Re: What is the shortest 5.56/223 AR15 that will make factor for SAPSA?

    You would be decreasing your dwell time on your gas system, assuming it's short enough that you can even cut it down that far

  3. #23
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    Default Re: What is the shortest 5.56/223 AR15 that will make factor for SAPSA?

    Quote Originally Posted by BBT View Post
    Talking about barrel length, hypothetically, what would happen if you shortened the barrel length from 16" to say 12"??
    Is it even possible?
    Functionality wise I mean?
    In theory it depends on the gas port size. On a gas port correctly sized for a 16" gun you might have cycling issues, that said most AR's are over gassed from factory (the theory is it would make them reliable with all types of ammo). So in theory you might be able to shorten it with no ill effects. Then there is also the ability to change out buffers and BCG's to lighter (or heavier) types to help with function.

  4. #24
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    Default Re: What is the shortest 5.56/223 AR15 that will make factor for SAPSA?

    Sorry if this is deemed a thread hi-jack. If so, I will move to new thread.

    Own a 10.5” with Saaima Still. Not in competing seriously, only club competionsions. Round count +/- 1,000.

    Shooting own 55gr reloads @ 2630 fps on average. No malfunction yet.

    Question:
    1. How can I confirm/check that chamber pressure is safe?

  5. #25

    Default Re: What is the shortest 5.56/223 AR15 that will make factor for SAPSA?

    I have a few different barrel length AR's in 223/556 including a 14.5” and a 10.5”; I have measured the velocity difference with the same ammo across these two. Unfortunately the pc all the data was saved on, was stolen but I seem to remember that there was a reasonably consistent 300fps drop with 55gr bullets from the 14.5” to the 10.5”. State 5.56 ammo would run at around 3050-3100fps in the 14.5” and around 2750-2800fps in the 10.5”, considering that you’ll need 2728fps to just make factor of 150, you'll be pushing the pressure dragon to maintain factor reliably with the short barrel. I think that even with heavier bullets you'll still be right at the top end of the pressure limits to get to the minimum required velocities not to mention the noise you'll have with the short barrel.
    For sport shooting where you need to make the 150 factor I believe that you'll be better served with a longer barrel and hopefully a longer gas system (if an AR dgi) that will smooth out the recoil cycle.
    The 10.5” with a Saimastill suppressor is still an absolute winner in the cool factor space.

  6. #26
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    Default Re: What is the shortest 5.56/223 AR15 that will make factor for SAPSA?

    Quote Originally Posted by Armed Preacher View Post
    I have a few different barrel length AR's in 223/556 including a 14.5” and a 10.5”; I have measured the velocity difference with the same ammo across these two. Unfortunately the pc all the data was saved on, was stolen but I seem to remember that there was a reasonably consistent 300fps drop with 55gr bullets from the 14.5” to the 10.5”. State 5.56 ammo would run at around 3050-3100fps in the 14.5” and around 2750-2800fps in the 10.5”, considering that you’ll need 2728fps to just make factor of 150, you'll be pushing the pressure dragon to maintain factor reliably with the short barrel. I think that even with heavier bullets you'll still be right at the top end of the pressure limits to get to the minimum required velocities not to mention the noise you'll have with the short barrel.
    For sport shooting where you need to make the 150 factor I believe that you'll be better served with a longer barrel and hopefully a longer gas system (if an AR dgi) that will smooth out the recoil cycle.
    The 10.5” with a Saimastill suppressor is still an absolute winner in the cool factor space.
    100% consistent with my experiences.
    "Always remember to pillage before you burn"
    Unknown Barbarian

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