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9mm AR upper decision...

GunNutGunNut Posts: 7,642 Senior Member
This one is coming around.  Getting closer by the day actually.  Going to build a PSA 9mm AR pistol that accepts Glock magazines.  Should I go with the 4" or the 7" upper?  I'm leaning to the 4", this will never be anything but a true HD/close quarter PDW and most probably will get a short can down the road.  But I'm willing to listen...



9mm AR upper decision... 14 votes

PSA 9mm 4" Upper
21%
wddodgeMichakavzorba 3 votes
PSA 9mm 7" Upper
78%
knitepoetDiver43JKPCHIRO1989shotgunshooter3BigslugSpkZeeRugerFanmitdr774lancebanyon 11 votes
«1

Replies

  • JunkCollectorJunkCollector Posts: 1,067 Senior Member
    I'd buy beer instead.

    Get more bang for my buck.

    With the price of ammo it would be good beer to boot.
  • GunNutGunNut Posts: 7,642 Senior Member
    I'd buy beer instead.

    Get more bang for my buck.

    With the price of ammo it would be good beer to boot.
    Meh, I can have beer anytime...  :D
  • GunNutGunNut Posts: 7,642 Senior Member
    I MIGHT even set it up with one of these, they make a right or left fold option.  Yes, you can fire with the stock folded...

  • JKPJKP Senior Member Posts: 2,538 Senior Member
    PSA 9mm 7" Upper
    7". Might as well use a full size pistol if you want a 4" barrel. 
  • GunNutGunNut Posts: 7,642 Senior Member
    JKP said:
    7". Might as well use a full size pistol if you want a 4" barrel. 
    I'm looking to stay as compact as possible AND even maybe conceal in a "murse" while gaining the steadier platform, ease of fast aimed multiple shots, and increased capacity of the Glock long sticks.  while this will most probably serve as my main HD weapon I can see packing this puppy and 5 32 rounders in a small shoulder bag or a Maxpedition sling type pack, and going for a stroll.  This could also sit on my lap in the car, something I can't legally do with my SBR.  Hell, this MIGHT replace my SBR...
  • CHIRO1989CHIRO1989 Senior Member Posts: 14,186 Senior Member
    PSA 9mm 7" Upper
    If you are going with more bulk get a 7", go with more muzzle velocity, longer site radius, and get the muzzle blast further away from you.
    I take no pleasure in the death of the wicked, but rather that they turn away from their ways and live. Eze 33:11
  • MichakavMichakav Senior Member Posts: 2,907 Senior Member
    PSA 9mm 4" Upper
    I would go 4 if getting a can and 7 if not.
  • Uncle FesterUncle Fester Senior Member Posts: 1,566 Senior Member
    JKP said:
    7". Might as well use a full size pistol if you want a 4" barrel. 
    I was going to buy a Ruger PC Pistol until I realized exactly how short the barrel.
  • mitdr774mitdr774 Member Posts: 1,767 Senior Member
    PSA 9mm 7" Upper
    GunNut said:
    I'd buy beer instead.

    Get more bang for my buck.

    With the price of ammo it would be good beer to boot.
    Meh, I can have beer anytime...  :D
    Scotch then......  I might have to have a glass tonight now.
  • sakodudesakodude Senior Member Posts: 4,546 Senior Member
    My idea of a pistol caliber carbine :#
  • zorbazorba Senior Member Posts: 24,981 Senior Member
    PSA 9mm 4" Upper
    The correct answer is, of course, BOTH!
    Honestly, I don't know enough about it to have an informed opinion, but if the OP is leaning towards the 4", I say "do it!".
    -Zorba, "The Veiled Male"

    "If you get it and didn't work for it, someone else worked for it and didn't get it..."
    )O(
  • MichakavMichakav Senior Member Posts: 2,907 Senior Member
    edited February 2021 #13
    PSA 9mm 4" Upper
    knitepoet said:
     Plus, not a lot of room for your hand out front with a 4".  
    Thats why I voted 4 if a can is going on it, 7 otherwise.
  • GunNutGunNut Posts: 7,642 Senior Member
    edited February 2021 #14
    Well just had a conversation with my gun “conscience” and he slapped me on the head.  7” it is...  :D

    I also just realized that the 4” barrel doesn’t even make it to the end of the forend and has one of them forward directing muzzle devices already tucked in there just to make it even.  That won’t do...
  • GunNutGunNut Posts: 7,642 Senior Member
    sakodude said:
    My idea of a pistol caliber carbine :#
    As beautiful as that gun is I already have too many pretty guns.  I need me some good hammers...
  • ZeeZee Senior Member Posts: 27,455 Senior Member
    PSA 9mm 7" Upper
    JKP said:
    7". Might as well use a full size pistol if you want a 4" barrel. 
    I was going to buy a Ruger PC Pistol until I realized exactly how short the barrel.
    I get 1,300 fps with 124gr Federal and Speer out of my Ruger PC Charger Pistol. 
    "To Hell with efficiency, it's performance we want!" - Elmer Keith
  • GunNutGunNut Posts: 7,642 Senior Member
    Zee said:
    JKP said:
    7". Might as well use a full size pistol if you want a 4" barrel. 
    I was going to buy a Ruger PC Pistol until I realized exactly how short the barrel.
    I get 1,300 fps with 124gr Federal and Speer out of my Ruger PC Charger Pistol. 
    Have you tried any 115gr +P out of it?
  • ZeeZee Senior Member Posts: 27,455 Senior Member
    PSA 9mm 7" Upper
    GunNut said:
    Zee said:
    JKP said:
    7". Might as well use a full size pistol if you want a 4" barrel. 
    I was going to buy a Ruger PC Pistol until I realized exactly how short the barrel.
    I get 1,300 fps with 124gr Federal and Speer out of my Ruger PC Charger Pistol. 
    Have you tried any 115gr +P out of it?

    "To Hell with efficiency, it's performance we want!" - Elmer Keith
  • GunNutGunNut Posts: 7,642 Senior Member
    Zee said:
    GunNut said:
    Zee said:
    JKP said:
    7". Might as well use a full size pistol if you want a 4" barrel. 
    I was going to buy a Ruger PC Pistol until I realized exactly how short the barrel.
    I get 1,300 fps with 124gr Federal and Speer out of my Ruger PC Charger Pistol. 
    Have you tried any 115gr +P out of it?

    Ok, what did I do now!?!?
  • ZeeZee Senior Member Posts: 27,455 Senior Member
    edited February 2021 #20
    PSA 9mm 7" Upper
    GunNut said:
    Zee said:
    GunNut said:
    Zee said:
    JKP said:
    7". Might as well use a full size pistol if you want a 4" barrel. 
    I was going to buy a Ruger PC Pistol until I realized exactly how short the barrel.
    I get 1,300 fps with 124gr Federal and Speer out of my Ruger PC Charger Pistol. 
    Have you tried any 115gr +P out of it?

    Ok, what did I do now!?!?
    Not a 115gr fan. Though, I’ve not experimented with the 9mm enough to have scientific grounds. Just prefer more mass. 
    "To Hell with efficiency, it's performance we want!" - Elmer Keith
  • GunNutGunNut Posts: 7,642 Senior Member
    Zee said:
    GunNut said:
    Zee said:
    GunNut said:
    Zee said:
    JKP said:
    7". Might as well use a full size pistol if you want a 4" barrel. 
    I was going to buy a Ruger PC Pistol until I realized exactly how short the barrel.
    I get 1,300 fps with 124gr Federal and Speer out of my Ruger PC Charger Pistol. 
    Have you tried any 115gr +P out of it?

    Ok, what did I do now!?!?
    Not a 115gr fan. Though, I’ve not experimented with the 9mm enough to have scientific grounds. Just prefer more mass. 
    YOU are the one who keeps telling me speed kills.  I’m just trying to understand Lord Vader... 
  • ZeeZee Senior Member Posts: 27,455 Senior Member
    edited February 2021 #22
    PSA 9mm 7" Upper
    It’s does. With sufficient mass behind it to penetrate to the juicy center. 

    A 55gr FBHP from my .220 Swift at almost 4,000 fps smoked a doe but didn’t exit her head the size of a grapefruit. 

    Speed kills. But, what’s your ultimate goal?  

    Balance. 


    "To Hell with efficiency, it's performance we want!" - Elmer Keith
  • BigslugBigslug Senior Member Posts: 9,324 Senior Member
    PSA 9mm 7" Upper
    Not a 115 grain fan either, or of 124.

    Gel results aren't tissue - fair enough - but the 147's ARE very consistent in reaching depths within the FBI's happy numbers range across the test barrier spectrum.  The lighter slugs seems to give up much of their momentum on the obstacle, making their penetration a little more variable.

    Just for sake of historical relevance, it was a 115 grain Silvertip entering through the upper arm that pancaked and stopped short of Michael Platt's vital organs in the 1986 Miami shootout, allowing him to continue to shoot FBI agents until slowly bleeding out through a severed brachial artery.  That was what led to the birth of the whole gelatin-based studies we use today.

    Even though the construction of the bullets has gotten better, you're still confined by the diameter, bullet materials, safe SAAMI pressure specs, and the velocities they generate.  A 115 grain hollowpoint lacks momentum, no matter how well constructed it is.  Comparatively, it's a ping pong ball.  A 147 is a golf ball.  Which would you rather have someone bounce off the back of your head?
    WWJMBD?

    "Nothing is safe from stupid." - Zee
  • shotgunshooter3shotgunshooter3 Senior Member Posts: 5,970 Senior Member
    PSA 9mm 7" Upper
    You already decided, but I vote 7".

    If you're already adding the bulk of an AR style receiver, brace, etc, why mess with the same barrel length as a Glock 19?
    - I am a rifleman with a poorly chosen screen name. -
    "Slow is smooth, smooth is fast, and speed is the economy of motion" - Scott Jedlinski
  • GunNutGunNut Posts: 7,642 Senior Member
    Wow, so it’s 7” being favored overwhelmingly.  Interesting to say the least.  Ok, mob rule, we’ll do a 7” upper.  

    The balance of speed and mass discussion is if great interest to me.  I have read of failures of 147gr projectiles to properly expand because of speed just not being there and while I like penetration I want a bullet to behave as advertised, otherwise I’m just shooting FMJs.  

    I’m also afraid that the gains I can get from the 7” barrel with the lighter bullets, giving me optimum performance and a consistent POA/POI relationship farther down range, will be negated with 147gr because of an arch trajectory and quick bleed of speed.   In other words, I never believed that there was enough powder in a bitty 9mm case to run a 147gr bullet to expand reliably.   Have I been wrong?
  • shotgunshooter3shotgunshooter3 Senior Member Posts: 5,970 Senior Member
    PSA 9mm 7" Upper
    At home defense distances, even in a large home, does it really matter?
    - I am a rifleman with a poorly chosen screen name. -
    "Slow is smooth, smooth is fast, and speed is the economy of motion" - Scott Jedlinski
  • GunNutGunNut Posts: 7,642 Senior Member
    At home defense distances, even in a large home, does it really matter?
    I might want to take this to Walmart... It's a dangerous place...  :D
  • BigslugBigslug Senior Member Posts: 9,324 Senior Member
    PSA 9mm 7" Upper
    GunNut said:
    Wow, so it’s 7” being favored overwhelmingly.  Interesting to say the least.  Ok, mob rule, we’ll do a 7” upper.  

    The balance of speed and mass discussion is if great interest to me.  I have read of failures of 147gr projectiles to properly expand because of speed just not being there and while I like penetration I want a bullet to behave as advertised, otherwise I’m just shooting FMJs.  

    I’m also afraid that the gains I can get from the 7” barrel with the lighter bullets, giving me optimum performance and a consistent POA/POI relationship farther down range, will be negated with 147gr because of an arch trajectory and quick bleed of speed.   In other words, I never believed that there was enough powder in a bitty 9mm case to run a 147gr bullet to expand reliably.   Have I been wrong?
    Considering that 230 grain .45's expand at 850 fps and less all the time. . .

    180 grain .40 S&W's expand at 1000 fps and less all the time. . .

    . . .the notion that a 147 grain 9mm at 1000 fps cannot expand seems a bit ill-founded.

    Hollowpoint tech of the '80's left a lot to be desired - in many areas.  We've moved on, but the stories plague those that have not kept up and circulate still.  Story of the world. . .  Truth is, we've done pretty well since the mid to late '90's

    As to trajectory. . .they're pistol rounds.  The trajectory is going to suck.  Period.  Paragraph.  Under a hundred yards, the differences in flight path between the weights of 9mm slugs will be effectively academic.  Beyond 100 yards they will all be mortars.  Best not to see a sand wedge as a driver.
    WWJMBD?

    "Nothing is safe from stupid." - Zee
  • GunNutGunNut Posts: 7,642 Senior Member
    Bigslug said:
    GunNut said:
    Wow, so it’s 7” being favored overwhelmingly.  Interesting to say the least.  Ok, mob rule, we’ll do a 7” upper.  

    The balance of speed and mass discussion is if great interest to me.  I have read of failures of 147gr projectiles to properly expand because of speed just not being there and while I like penetration I want a bullet to behave as advertised, otherwise I’m just shooting FMJs.  

    I’m also afraid that the gains I can get from the 7” barrel with the lighter bullets, giving me optimum performance and a consistent POA/POI relationship farther down range, will be negated with 147gr because of an arch trajectory and quick bleed of speed.   In other words, I never believed that there was enough powder in a bitty 9mm case to run a 147gr bullet to expand reliably.   Have I been wrong?
    Considering that 230 grain .45's expand at 850 fps and less all the time. . .

    180 grain .40 S&W's expand at 1000 fps and less all the time. . .

    . . .the notion that a 147 grain 9mm at 1000 fps cannot expand seems a bit ill-founded.

    Hollowpoint tech of the '80's left a lot to be desired - in many areas.  We've moved on, but the stories plague those that have not kept up and circulate still.  Story of the world. . .  Truth is, we've done pretty well since the mid to late '90's

    As to trajectory. . .they're pistol rounds.  The trajectory is going to suck.  Period.  Paragraph.  Under a hundred yards, the differences in flight path between the weights of 9mm slugs will be effectively academic.  Beyond 100 yards they will all be mortars.  Best not to see a sand wedge as a driver.
    Lot's to think about.  Good info, thanks.
  • lancebanyonlancebanyon Posts: 32 Member
    PSA 9mm 7" Upper
    I built a 9mm lower and am looking at a 9mm 16" upper for it. 
  • GunNutGunNut Posts: 7,642 Senior Member
    I built a 9mm lower and am looking at a 9mm 16" upper for it. 
    That could be fun but I personally don’t have an interest for a full length 9mm carbine again.  I owned a Ruger PC9 for a while and it was a neat gun but I fell out of love quickly because I could not figure out what to do with the darn thing after a while.
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