Ar pistol build - 7 or 10.5"? Pros/cons of each

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  • Merlin593

    Active Member
    Mar 29, 2013
    353
    Towson, MD
    Looking to do another AR build and pretty much have decided on a pistol.
    Debating on 7" vs. 10.5"
    I don't have a CC permit so more compactness of the 7" in terms of using it as truck gun won't apply.
    I was looking at a buffer tube or Sig brace.
    I'm looking for feedback on the gas systems (pistol vs carbine), gun balance, buffer tube vs. sig brace, noise comparison, weight, etc.
    Any pics you'd want to share of your own pistols would be appreciated to help provide build ideas/manufacturers.
    Thanks in advance for your replies.
    Best,
    Jim
     

    BradMacc82

    Ultimate Member
    Industry Partner
    Aug 17, 2011
    26,177
    7.5" is fun for a range toy, that's about it, IMO. You lose the one thing the round needs to be effective - velocity, as evident by the fireballs of still burning propellant a 7.5" throws out the muzzle.

    7.5" can also be a bit finicky due to the short dwell-time, the action is trying to eject the spent casing before the casing has contracted in the chamber, which means the extractor kicks over the rim during the attempt at extraction and you have a casing left in the chamber.

    10.5" would be my choice, but that's just me.

    **Actually, my AR-pistols were in 300BLK, but for 5.56, I'd go with a 10.5" at the minimum.
     

    Petar

    Member
    Nov 18, 2010
    532
    7.5" is fun for a range toy, that's about it, IMO. You lose the one thing the round needs to be effective - velocity, as evident by the fireballs of still burning propellant a 7.5" throws out the muzzle.

    7.5" can also be a bit finicky due to the short dwell-time, the action is trying to eject the spent casing before the casing has contracted in the chamber, which means the extractor kicks over the rim during the attempt at extraction and you have a casing left in the chamber.

    10.5" would be my choice, but that's just me.

    **Actually, my AR-pistols were in 300BLK, but for 5.56, I'd go with a 10.5" at the minimum.

    Agree:thumbsup:
     

    Silverlode

    Ultimate Member
    Aug 16, 2010
    4,797
    Frederick
    7.5" is fun for a range toy, that's about it, IMO. You lose the one thing the round needs to be effective - velocity, as evident by the fireballs of still burning propellant a 7.5" throws out the muzzle.

    7.5" can also be a bit finicky due to the short dwell-time, the action is trying to eject the spent casing before the casing has contracted in the chamber, which means the extractor kicks over the rim during the attempt at extraction and you have a casing left in the chamber.

    10.5" would be my choice, but that's just me.

    **Actually, my AR-pistols were in 300BLK, but for 5.56, I'd go with a 10.5" at the minimum.

    I too subscribe to this thinking. In fact I went with a 12.5" Daniel Defense barrel because the drop in velocity between that and a 10.5" is dramatic, let alone a 7.5". I did have one of those too at one point. It was a toy, nothing more.
     

    Bluemax

    Member in good standing
    Jun 12, 2010
    184
    southern maryland
    Barrel Velocity (55gr M193)Velocity (62gr SS109)Energy (55gr M193)Energy (62gr SS109)
    Length Feet per second Feet per Second Foot Pounds Foot Pounds
    10" 2739 2627 916 950
    11.5" 2872 2738 1007 1032
    14.5" 3064 2907 1146 1163
    16" 3132 2989 1198 1230
    20" 3259 3095 1297 1318
    21.5" 3386 3185 1342 1373
    24" 3315 3158 1342 1373
    26" 3391 3231 1404 1437


    Food for thought.
     

    Silverlode

    Ultimate Member
    Aug 16, 2010
    4,797
    Frederick
    AR pistol? 7.5"
    AR SBR? 10.5" or 11.5"

    Heh, my 12.2" 300BLK was a pistol - granted it was a BIG pistol, but a pistol nonetheless. :D

    AR LBP!

    photo.JPG
     

    BradMacc82

    Ultimate Member
    Industry Partner
    Aug 17, 2011
    26,177
    Just suck it up and build SBRs, guys. You know you want to.

    Intended to SBR, but got bored with the idea and sold all that stuff off.

    I'll do an SBR eventually, but for now I have no want or need to do one.
     

    Merlin593

    Active Member
    Mar 29, 2013
    353
    Towson, MD
    thanks for all the replies so far
    keep em coming...
    don't want the time, hassle and $ associated with an SBR so sticking to pistol only.
     

    Speed3

    Ultimate Member
    Aug 19, 2011
    7,816
    MD
    Notify once per year for each destination.

    Or put a 16+" upper on it, and take it anywhere you want without any issues.

    Yep and what happens if you want to go somewhere with it that you didn't plan a year in advance and you leave in a week?I don't have to notify anyone about my suppressor or my ar pistol.
     

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