9mm AR?

[Reagans Rascals]

Someone please explain the existence of this platform to me.

With the MP5 phased out by MK18ish 5.56 SBR's in favor of better ballistics, why would someone convert their AR to 9mm?

From those I have seen, 9mm AR's are usually short barreled, probably around 8-10', so the switch wasn't a step-up over the 8.9" MP5 barrel.

The only viable reason I can see for this type of conversion, at the Dept. level, is perhaps its easier and cheaper to convert a stable of M4's or Colt Commandos to 9mm instead of purchasing MP5s. If this is the case though, why would they even switch to the 9mm from the 5.56 to begin with?

Is there any logical reason for this, besides simply because they could?

[rob_s]

Training.

There are places I can shoot my 9mm AR that I can't shoot centerfire rifle calibers.



Suppression.

I can shoot subsonic ammo in my 9mm AR and it will cycle just like the supersonic but completely hearing safe.

[C4IGrant]

Someone please explain the existence of this platform to me.

With the MP5 phased out by MK18ish 5.56 SBR's in favor of better ballistics, why would someone convert their AR to 9mm?

From those I have seen, 9mm AR's are usually short barreled, probably around 8-10', so the switch wasn't a step-up over the 8.9" MP5 barrel.

The only viable reason I can see for this type of conversion, at the Dept. level, is perhaps its easier and cheaper to convert a stable of M4's or Colt Commandos to 9mm instead of purchasing MP5s. If this is the case though, why would they even switch to the 9mm from the 5.56 to begin with?

Is there any logical reason for this, besides simply because they could?

Cost of shooting it and many shoot houses do not allow .223.



C4

[Reagans Rascals]

I understand the cost and suppression aspects, however;

I was led to believe that the 9mm offers high barrier penetration than the 5.56, as the 5.56's velocity is the primary factor in its armor and barrier penetration, which is instantaneously bled off once it strikes a target, whereas the 9mm's capability is in its mass, which it retains throughout penetration.

Wouldn't this make the 5.56 better in a shoot house than 9mm?

But I guess in close-quarters live fire drills, the 9mm would be a better training round due to reduced chance of armor penetration in the even of an ND/AD.

[discreet]

9mm is a pistol round, while .223 is not, thus why many indoor ranges etc don't allow rifle rounds, regardless of if a specific round can penetrate walls more etc.

9mm has many different advantages in different areas. Many people just like them because they are fun. Many like them because of the size of magazines. I think there are actually so many variables that play into why some like 9mm, it's almost impossible to discuss true viability, because each person wants something for their own reason.

Also, there has been more than a couple threads just on this subject lately, so I suggest you dig through this forum section. Lots of info. 9mm isn't for everyone, but definitely still has it's place.

Might I mention, just because military or LEO does something, doesn't mean it makes the old gun they switched away from bad (or even caliber). The 9mm on this forum is a very highly regarded round by many might I also mention.

[devinsdad]

Went beyond a conversion, built a 9mm only SBR off a RRA dedicated magwell lower. Why..the 9mm is a fun little round, has no recoil, easy to teach my kids on without them getting nervous, cheaper than 5.56, ability to use at indoor ranges...did I mention fun to shoot? Not to mention, it was the first AR that my son and I put together. The 9mm is one of several AR's I own...but seems to get a lot more rounds thru it than others.

[kruzan]

I understand the cost and suppression aspects, however;

I was led to believe that the 9mm offers high barrier penetration than the 5.56, as the 5.56's velocity is the primary factor in its armor and barrier penetration, which is instantaneously bled off once it strikes a target, whereas the 9mm's capability is in its mass, which it retains throughout penetration.

Wouldn't this make the 5.56 better in a shoot house than 9mm?

But I guess in close-quarters live fire drills, the 9mm would be a better training round due to reduced chance of armor penetration in the even of an ND/AD.

Whats the deal with that? Some are always saying that the 9mm is going to be worse with that so it is therefore the reason that the MP5 or similar is now not being deamed as useful with CQB?

If that were the case wouldn't frangible rounds or similar specialty rounds just nullify that argument?

If you prefer the power and versatility of the 5.56 so be it, but that won't improve its performance in a very short barrel.

[kmrtnsn]

My wife's agency transitioned from the Uzi to the Colt 9mm SMG a decade ago. I have never been a fan of the Colt SMG. Anyone running them is doing so solely on the per unit price as they are the worst conglomeration of compromises ever assembled in one platform. For those needing a 9mm SMG, there are so many better alternatives out there, especially, now. H&K, B&T, anyone?

[C4IGrant]

I understand the cost and suppression aspects, however;

I was led to believe that the 9mm offers high barrier penetration than the 5.56, as the 5.56's velocity is the primary factor in its armor and barrier penetration, which is instantaneously bled off once it strikes a target, whereas the 9mm's capability is in its mass, which it retains throughout penetration.

Wouldn't this make the 5.56 better in a shoot house than 9mm?

But I guess in close-quarters live fire drills, the 9mm would be a better training round due to reduced chance of armor penetration in the even of an ND/AD.

Most bullet traps are either rated for HG rounds or FRANG .223/5.56. It is far more common to find ones rated for HG.

C4

[LONGBOWAH]

Training.

There are places I can shoot my 9mm AR that I can't shoot centerfire rifle calibers.



Suppression.

I can shoot subsonic ammo in my 9mm AR and it will cycle just like the supersonic but completely hearing safe.

...plus ammo is less expensive and easier to handload.