ar15 pistol reliability?

[Iraqgunz]

The last time this question was asked (about 1 week ago) I said that they are a tacticool gimmick. I stand by that statment. I'd be willing to bet that someone with a good pistol that practices and knows how to shoot will outshoot someone with a cool guy AR pistol.

Even if you live in a non-SBR state I don't see them as a viable alternative.

1. A case of 9mm is still cheaper than a case of 5.56

2. A good 9mm (example only) is going to be cheaper to buy and more reliable.

3. The guy with the AR pistol probably will not practice as much as they pistol guy for reasons mentioned above.

4. The muzzle flash from these things can be horrendous. Maybe a Battle Comp would help mitigate that.

5. I can carry the pistol on my person and don't have to worry about any other security concerns when I have to leave my AR pistol in the vehicle.

JM2CWYMMV.

[Magic_Salad0892]

The only AR pistol I would consider battle-worthy would be a Noveske Diplomat in 6.8x43mm with the smallest gas port it could run reliably on.

I would say suppress it, but that would void the warranty on a perfectly good can.

Wear some ****in' ear muffs. O_O

An AAC 300 BLK without a stock would be sweet. Or a KAC PDW. (Ideal)

[Iraqgunz]

Why would that void the warranty?

The only AR pistol I would consider battle-worthy would be a Noveske Diplomat in 6.8x43mm with the smallest gas port it could run reliably on.

I would say suppress it, but that would void the warranty on a perfectly good can.

Wear some ****in' ear muffs. O_O

An AAC 300 BLK without a stock would be sweet. Or a KAC PDW. (Ideal)

[shadow65]

Nearly all Suppressor manufacturers will not warranty a suppressor on anything less than 10.5".

[Iraqgunz]

Is that fact (somewhere) or internet conjecture? Just curious because I started doing some research and this is one of the few things I found.

I am not condoning it's use or AR pistols, just saying.

What is the minimum barrel length recommendation?

Gemtech, and other manufacturers do not recommend the use of barrels shorter than 10.5". There are three primary reasons for this:

Stability: The standard 1:7 twist rate of 5.56mm barrels barely provides one full turn in the rifling before releasing the bullet when using a 7" or 7.5" barrel. This does not impart enough spin on the projectile to properly stabilize it during the critical first few inches of flight as it passes through the suppressor. While the bullet may stabilize downrange suitably to be accurate when shooting unsuppressed, it will not stabilize and will strike baffles when a suppressor is mounted. Some barrels use a 1:8 or 1:9 twist making the problem even worse.

Velocity: The 5.56mm cartridge is also very velocity dependent for stability. Very short barrels, less than 10.5" do not allow sufficient velocity to properly stabilize the round, thereby exacerbating the stability problem described above.

Erosion: The 5.56mm cartridge was designed to burn its powder in a 20" service rifle (M16A1, M16A2). The maximum flame temperature and pressure happen at around 7" from the chamber. Short barrels under 10.5" cause excessive flame temperature and pressure within the entrance chamber of the suppressor. This causes excessive erosion of the blast baffle because hot, high pressure particles of unburnt powder sandblast this baffle. So, provided you are lucky enough to avoid a baffle strike due the above two issues, the suppressor will be worn out in a very short period of time due to erosion.

Although a few inches of barrel doesn't seem like it would make much difference, it really does. The uncorking pressure at the muzzle of a 7" barrel is almost double that of a 10.5" barrel.

Nearly all Suppressor manufacturers will not warranty a suppressor on anything less than 10.5".

[Iraqgunz]

Well I have been doing some research and contacted a few suppressor manufacturers about their warranty in relation to barrels of less than 10.5" inches. In addition to learning that some will and will not void the warranty, there were a few that actually provided some good background information.

Now for those of you who still think that an AR pistol is a good option (less than 10.5" especially) you should really take some time to read this email that I received.

Dear Customer,

Most 5.56 rifles are equipped with 1/7 twist barrels (1 full rotation per 7 inches of barrel). This provides for a little over one full turn in the rifling before the bullet is released when used in a 7.5" Barrel. Due to the lack of gyration imparted on the projectile, the round will not be properly stabilized during the first few inches of flight, and while it is entirely plausible that the round will eventually stabilize further downrange; it will likely strike a baffle before it has the opportunity to do so. The effect is further worsened when using a 1/8 or 1/9 twist barrel. Additionally, these short barrel rifles (<10.5") typically do not yield adequate velocity upon the projectile within that short 7" of barrel, further augmenting the aforementioned stability issue.

If the Mini was used on a 7.5” AR pistol and you were fortunate enough to not encounter a baffle strike, you would note that the effectiveness of the suppressor would be decreased. Most of the unburnt powder would ignite upon leaving the Suppressor, providing for plenty of noise and flash.
Furthermore, when used in conjunction with a short barreled rifle, service life of a Suppressor will be drastically shortened. The 5.56mm cartridge was designed to burn all powder within a 20" barrel (e.g. M16A1, M16A2). Maximum pressure and temperature is achieved roughly 7" from the chamber of the rifle; in close proximity to the access-chamber of the Suppressor. The hot and high pressure particles of unburnt powder are then accelerated through the baffles of your Suppressor, putting disproportionate wear on your product.


Thank You

[shadow65]

From my experience, I use a .308 can on my 7.5". Bigger exit hole, longer can. Never had a baffle strike from the 1/8 barrel. And it quiets it down to where I can shoot it without ear protection. It doesn't "sound" any different than my 10.5". Never ran a decibel test, nor do I have the equipment to do so. I go by what I hear instead of what I read anyhow.
The difference between the 5.56 and .30 caliber exit hole I'm sure helps. The extra length may also help. But it does work and works well.
It's a S.A.S. suppressor and Tim will warranty his. Built like a tank.

I have no doubt that a 7.5" is very hard on any suppressor. I would never use a can for lots of shots on a 7.5". I certainly wouldn't use it for a FA set up.
Good info Iraqgunz.

[georgiaboy454]

Took my Rock River 10.5" AR pistol out to the range today for the first time. It was like being a little kid at Christmas. Muzzle blast wasn't what I thought it would be, in fact it wasn't that bad! I got the Eotech dialed in and was slapping steel rams at 20, 50, and 80 yards. This is a project that will eventually be turned into a SBR(waiting on that tax return). I say go with a good reputable company and you should be alright. Also, I wouldn't run anything shorter than 10.5" For defensive use I only run Hornady TAP 75grain "HOLLOWPOINTS"!

[Clint]

Stability: The standard 1:7 twist rate of 5.56mm barrels barely provides one full turn in the rifling before releasing the bullet when using a 7" or 7.5" barrel. This does not impart enough spin on the projectile to properly stabilize it during the critical first few inches of flight as it passes through the suppressor. While the bullet may stabilize downrange suitably to be accurate when shooting unsuppressed, it will not stabilize and will strike baffles when a suppressor is mounted. Some barrels use a 1:8 or 1:9 twist making the problem even worse.

Just wanted to clear this up.

The low stability of rounds fired from short barrels at low velocity is due to low RPM, not how many revolutions the round makes while in the barrel.

Look at all the 5" pistol barrels with 1:10 and slower twist.

[Iraqgunz]

I was simply relaying the information sent to me by the customer service people.

Just wanted to clear this up.

The low stability of rounds fired from short barrels at low velocity is due to low RPM, not how many revolutions the round makes while in the barrel.

Look at all the 5" pistol barrels with 1:10 and slower twist.