7.5 inch AR-15 reliability

**RyanB** · 05-31-10, 15:44

If I were to use a 7.5, it would have a flash suppressor on it. By the time you put a KX3 on it, you might has well have just gotten a MK18.

**miamitj** · 06-13-10, 10:17

http://www.youtube.com/watch?v=jj0xq637mi4

I was testing a lower a buddy recently built with my MODEL 1 7.5" upper. Thought I would share how that shitty, horribly built model one upper is still running flawlessly after tens of thousands of rounds even when suppressed and full auto.

**Zeus** · 06-13-10, 19:57

Originally Posted by miamitj

Thought I would share how that shitty, horribly built model one upper is still running flawlessly after tens of thousands of rounds even when suppressed and full auto.

Arguably, people don't realize that 90% of the reliability of an upper IS the BCG gas ports being the same.

Here is a link to a newer 7.5" thread that I started that's mighty damn interesting!

https://www.m4carbine.net/showthread.php?t=55382

**justin_247** · 01-12-11, 03:23

Can somebody please tell me the utility of this short of a barrel? The only reason one needs to go that short is because of the design of the AR in the first place (the buffer is behind the carrier instead of above it, which means you can't use a folding stock).

10.5" is already loud as heck. I can only imagine how insane this would be in a vehicle - I'm sure you'd destroy your ear drums as you try to shoot out the window, unless you had a KX3 directing the blast forward, but even then it would be loud.

With the KX3, the overall weapon length with the stock retracted is about 25".

For 5.56, I would much rather run a SCAR-CQC (21" overall length with stock folded) with an M4-2000 (adding 5.1" to the length).

Much better would be an MP-5, I would think.

**miamitj** · 01-12-11, 05:42

Originally Posted by justin_247

Can somebody please tell me the utility of this short of a barrel? The only reason one needs to go that short is because of the design of the AR in the first place (the buffer is behind the carrier instead of above it, which means you can't use a folding stock).

10.5" is already loud as heck. I can only imagine how insane this would be in a vehicle - I'm sure you'd destroy your ear drums as you try to shoot out the window, unless you had a KX3 directing the blast forward, but even then it would be loud.

At times I have both back and wrist issues. I need a light gun for long demanding courses. In FEB for example I will be attending two classes within weeks of wrist surgery (most likely Ill be in a cast) so my 7.5" ar will be sweet since I will be running one handed the entire time.

Its also my HD gun. Its the shortest suppressed AR platform you will find. Yea a SCAR would be short with a stock folded but that will take away my option to shoulder the weapon. A folded stock rifle for me is only good for storage.

As for the noise, on the range it is not as bad as many would think. For HD, I run suppressed. Look two posts above for video of me running it suppressed and full-auto.

**justin_247** · 01-12-11, 09:11

Originally Posted by miamitj

Its the shortest suppressed AR platform you will find. Yea a SCAR would be short with a stock folded but that will take away my option to shoulder the weapon. A folded stock rifle for me is only good for storage.

Even with the stock extended it's as short as an AR-based PDW. I just don't get it, I suppose...

**justin_247** · 01-12-11, 09:13

Oh, and how much damage are you causing to your suppressor baffles with that short of a barrel?

**scottryan** · 01-12-11, 09:29

Originally Posted by miamitj

I've been running a 7.5 AR for 4+ years. My rifle has seen well over 30K rounds and runs flawless with everything I have tossed at it with the exception of wolf. I have also been known to run it suppressed but the barrel is pretty shot out now so I keep the can off of it.

My secret, it is a model 1 7.5" upper. Yea they get the worst reviews but my research at the time showed people had 100% reliability with their 7.5" setup.

We can't take you serously when you are running a YHM rail, Model 1 upper, and some off brand silencer.