Glock Talk banner

Best Pistol barrel length?

3K views 27 replies 12 participants last post by  gt joe 
#1 ·
I am researching building or maybe purchasing an AR pistol upper. I was curious what the best barrel length is for reliability and shoot-ability. I will be keeping this a pistol, so no plans of an SBR or a suppressor. Thank you.
 
#6 ·
Not an expert by any means but from the research I did before I built mine I found that 10.5" to 11.5" with the Carbine length gas system is suppose to be easier on the gun so it'll last longer and also be more reliable. I find that the 10.5" I built is just about perfect and it ran great first time out with zero issues. A lot depends on what you plan on doing with the gun, if it's just a "Fun Gun" then a shorter barrel would be fine since it probably won't get shot as much and reliability doesn't need to be 100% but for a serious CQB/Home Defense gun I'd stick with 10.5" or longer. JMHO, YMMV.
 
  • Like
Reactions: Michael Rex
#15 ·
Ditto to what everyone else said. When you buy a stripped lower it's marked down as an "Other" because it's not a long gun or a handgun so it can be built into either. I've also used Anderson Lowers on several builds and they work great. You also can't beat the price. On nice thing about building a Carbine Length gas system pistol is that you'll have plenty of options for forearms since it's the same as the M4 Carbine. With a Pistol Length gas system you're options will be somewhat limited.
 
#16 ·
I was nervous about my first 10.5" pistol, thinking back to hearing horror stories about how short ARs don't run right or you will go deaf even with hearing protection. The fact is with carbine length gas system they basically operate like 16 inchers, you just have to make sure you are using ammo appropriate to the length (eg. M193 isn't a great choice for longer ranges because of the velocity loss).

As handy as a 10.5" is now I want to do a 8.5" 300 BLK. I wish I had a 30 cal silencer already but I'm waiting to see what happens with the federal legislation.
 
  • Like
Reactions: Michael Rex
#17 ·
Ditto to what everyone else said. When you buy a stripped lower it's marked down as an "Other" because it's not a long gun or a handgun so it can be built into either. I've also used Anderson Lowers on several builds and they work great. You also can't beat the price. On nice thing about building a Carbine Length gas system pistol is that you'll have plenty of options for forearms since it's the same as the M4 Carbine. With a Pistol Length gas system you're options will be somewhat limited.
I don't get it, isn't the carbine tube longer than the pistol tube? Or are you talking about a 16" pistol.
 
#23 ·
This is a topic I'm very interested in!
I think I'd like a 7.5" 5.56/.223 with a flashcan or suppressor and an arm brace.
Something like this...
View attachment 332405
Think it's a mistake lengthwise?
That's what I was thinking, maybe a little longer. What I am going for is to separate the upper and lower and carry it in a back pack. I'd rather do the blade brace thingy just because its thinner.
 
#24 ·
A 10.5"-11.5" with a Carbine Length Gas System(7" gas tube) is the same length as a, well, Carbine so it'll take the same handguards that you'd put on your Carbine. With a Pistol Length Gas System(5" tube IIRC) you have to get Pistol Length handguards and stuff to work.
With a Mid-Length system it'll have a 9" gas tube and the Rifle Length is a 12" gas tube. So it's pretty easy to remember, all odd numbers(5,7 and 9 until you get to Rifle then it's 12" for the gas tube length) I think the Carbine Length gas systems work better on a pistol than the shorter barrel and shorter gas systems do since they beat up the bolt carrier and stuff much less.
 
#25 · (Edited)
7.5" is a bit short even for 300 BLK but it's very short for 5.56. If you want it go for it but I wouldn't use it for defense. Many silencers aren't even rated for 5.56 that short IIRC, but you can find some that are.

If I did 7.5" it would definitely be 300 BLK over 5.56 but 7.5" is the absolute minimum I would consider for 300 BLK.
 
  • Like
Reactions: Brass3
#27 · (Edited)
The velocity loss in 7.5" is just terrible for 5.56. It would probably still be ok for close-in distances but the other issue I guess is the blast just gets worse, going to be horrendous without a silencer. If I'm going to use a rifle cartridge I want it to still be effective at longer distances. Again, we're talking about a defensive piece here. For a range toy it doesn't matter.

The red line is the graph is the minimum velocity for M855 ammo to produce a lethal wound and that's at point-blank range I think. Not that you'd use M855 but it illustrates the point. M195 would be similar, roughly. You can see below 10" the velocity drops off rapidly. This is why we think 10.5" is the sweet spot for short barreled 5.56s.



If I had to have 7.5" or shorter I'd go with a 9mm like a Zenith Z-5P. Put a folding arm brace on that baby and a QD silencer and you are all set.

 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top