7.5" vs 10.5" AR pistol

[Certaindeaf]

7.5in is way too short IMO. I did build one and ended up parting it our for a 10.5in. it just wasnt fun to shoot and every loud even with a fortis muzzle brake and blast shield still hurt your face. i couldnt imagine shooting that indoors or being surrounded walls of the sort. My 10.5 i did a adjustable gas block, captured buffer spring, and lighted BCG it shoots very flat and all around better decision in my book. you can shoot lighter bullet weight to maintain velocity to keep it effective but not by much.

No one can get that ammunition so of course I didn't click.

 

[dinky450]

No one can get that ammunition so of course I didn't click.

here is another link looking at lighter bullet weight on regular ammo.

5.56/.223 ballistic test carbine vs SBR -

5.56/.223 ballistic test carbine vs SBR I have been working on a a few projects for Barnes Precision Machine, one of which was a ballistic test for a common barrel length for SBR and compare that to the AR-15 carbine 16″ barrel. Some history of the 5.56 to begin with. The 5.56x45mm NATO began...

rangehot.com

 

[Aero Denezol]

9-hole Reviews did their 500 yard course w/ the 10.5" AR pistol, it is worth watching. Like most have already said, you lose performance with the shorter barrel. But it's not going to matter at 100 yards.

 

[Stomper]

The whole 10.3"/10.5" number came around because it is the shortest length barrel that can still use a standard FSB and carbine gas system, but they can be finicky. I won't go any shorter than 11.5" in 5.56 due to loss of velocity (terminal performance) and dwell time (operational performance). With a 11.5" vs 10.5" you get 4% increase in length of weapon with a 40% increase in dwell time, which translates to a very small increase in size vs a major increase in reliability.

This.

The CAR-15's (pre M-4 days) we ran with back in the 80's (and early 90's) were 11.5" which was determined to be the "sweet spot" of ballistic performance and reliability for the platform.

So, that's the way I still roll today.

 

[Kruel J]

9-hole Reviews did their 500 yard course w/ the 10.5" AR pistol, it is worth watching. Like most have already said, you lose performance with the shorter barrel. But it's not going to matter at 100 yards.

For what most people use AR pistols for (PDW), it really doesn't.

Screw it, ballistics be damned! Go with a 2" barrel!

The Firearm Blog - Firearms not Politics

Firearms not Politics

www.thefirearmblog.com

 

[Kruel J]

This.

The CAR-15's (pre M-4 days) we ran with back in the 80's (and early 90's) were 11.5" which was determined to be the "sweet spot" of ballistic performance and reliability for the platform.

So, that's the way I still roll today.

View attachment 1084084

Dude that's barely a "pistol". You need to SBR both of them!

 

[Longwalkhome]

I bought a 10.5 upper from a member here and proceeded to put together what I thought I wanted. Bought an Anderson lower registered as a handgun then started to put upper on it. Front pin would not go through. Never had an upper without a forward assist and with no name on the upper it took a while to figure what the problem was.

Pin hole had coating in it so I ran a bore brush through it and removed coating then the pin fit perfectly.

Next problem was sights, I couldn't get two different Vortex sites to zero for some reason. Bought them used from guys here but they should have worked and didn't. Ended up with a Trijicon red dot and very happy with the set up.


Blast is no problem and I expected worse. I am so happy with how it turned out I bought another upper from a member here to start another gun. Tried his upper and it shot and ran perfect. Fit perfect too and like past deals with him he only sells great stuff.

 

[Stomper]

Dude that's barely a "pistol". You need to SBR both of them!

I know, but I am enjoying the current loophole of it still being a "pistol" and being able to go on road trips across state lines without an ATF permission slip.

 

[titsonritz]

Dude that's barely a "pistol". You need to SBR both of them!

I need to put up some pics of 12.5"

 

[orygun]

I need to put up some pics of 12.5"

I assume you're still talking about AR barrel length?

 

[titsonritz]

I assume you're still talking about AR barrel length?

 

[Geardo]

I went with BCM 11.5, kind of a pseudo MK18 Mod0 setup

This is what I am doing as well.

 

[Geardo]

Then again like most, you take off 4-6 inches of barrel, only to add 6-8" of suppressor!

Better than a 22" long barrel+suppressor setup!

 

[Member 34319]

Better than a 22" long barrel+suppressor setup!

At 22" I'll just shoot it loud!

 

[titsonritz]

I built a 7.5" upper for a guy and he loves it and it's spectacular fire balls. Not my cup of tea but to each their own. I have settled on 11.5" as the sweet spot for performance and wieldability. It is pretty dang accurate out to 200 with just irons or a red dot. I may have to change the three prong flash hider though as it controls flash very well but you can feel the ring in your fillings when you shoot it. Sounds like a damn tuning fork.

Check out the White Sound Defense FOSSA it is extremely effective at flash suppression without the ring.

 

[RobMa]

This is what I am doing as well.

@Geardo

I am selling the upper if you are interested... PM me for more info if you would like

 

[2A2Dend]

I have two complete 7" uppers, I may sell in the near future.

 

[Geardo]

@Geardo

I am selling the upper if you are interested... PM me for more info if you would like

I already have the parts on hand for mine just haven't assembled yet. Thank you though!

 

[mhayd93]

I went through this exact same progression and ended up settling on a…16" Mid Length!

I have absolutely nothing against SBR/AR pistols, but I ended up coming to a different conclusion than others here; cutting off 6" of barrel really didn't make the gun feel that much more maneuverable or compact. An AR in 223/5.56 excels with 16-20" barrels, and in my hands those "standard" configurations "swing" much more naturally.

If I ever did another short barreled build, I wouldn't go any shorter than 10.5" though. The 7.5" I had was the most uncomfortable and unenjoyable firearm I've ever shot!

 

[Five-0]

I say you gotta try them all. I wouldnt choose a 7.5 if thats all I had, but I have one and its fun. Its not my go to if SHTF, unless I need a 556 backpack gun.